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GHC(1) Glasgow Haskell Compiler GHC(1) NAME ghc - the Glasgow Haskell Compiler SYNOPSIS ghc [option|filename] ghci [option|filename] DESCRIPTION This manual page documents briefly the ghc and ghci commands. Note that ghci is not yet available on all architectures. Extensive documentation is available in various other formats including PDF <https://down- loads.haskell.org/ghc/latest/docs/users_guide.pdf> and HTML <https://downloads.haskell.org/ghc/latest/docs/html/>. Each of GHC's command line options is classified as either static or dynamic. A static flag may only be specified on the command line, whereas a dynamic flag may also be given in an OPTIONS pragma in a source file or set from the GHCi command-line with :set . As a rule of thumb, all the language options are dynamic, as are the warning options and the debugging options. The rest are static, with the notable exceptions of -v, -cpp, -fasm, -fvia-C, -fllvm, and -#include. The OPTIONS sections lists the status of each flag. Common suffixes of file names for Haskell are: .hs Haskell source code; preprocess, compile .lhs literate Haskell source; unlit, preprocess, compile .hi Interface file; contains information about exported symbols .hc intermediate C files .way_o object files for "way" way; common ways are: dyn dynamically-linked p built with profiling .way_hi interface files for "way" way; common ways are: OPTIONS Code generation -dynamic-too -fasm -fllvm -fbyte-code -fbyte-code-and-ob- ject-code -fexpose-internal-symbols -fexternal-dynamic-refs -fllvm -fasm -fno-code -fobject-code -fPIC -fPIE -fpre- fer-byte-code -fwrite-if-simplified-core -fwrite-interface Debugging the compiler -dasm-lint -dcmm-lint -dcore-lint -ddisable-js-c-sources -ddis- able-js-minifier -ddump-asm -ddump-asm-conflicts -ddump-asm-liveness -ddump-asm-native -ddump-asm-regalloc -ddump-asm-regalloc-stages -ddump-asm-stats -ddump-bcos -ddump-c-backend -ddump-call-arity -ddump-cfg-weights -ddump-cmm -ddump-cmm-caf -ddump-cmm-cbe -ddump-cmm-cfg -ddump-cmm-cps -ddump-cmm-from-stg -ddump-cmm-info -ddump-cmm-opt -ddump-cmm-proc -ddump-cmm-procmap -ddump-cmm-raw -ddump-cmm-sink -ddump-cmm-sp -ddump-cmm-split -ddump-cmm-switch -ddump-cmm-thread-sanitizer -ddump-cmm-verbose -ddump-cmm-ver- bose-by-proc -ddump-core-stats -ddump-cpr-signatures -ddump-cpranal -ddump-cs-trace -ddump-cse -ddump-debug -ddump-deriv -ddump-dmd-signatures -ddump-dmdanal -ddump-ds -ddump-ds-preopt -ddump-ec-trace -ddump-exitify -ddump-fast- strings -ddump-file-prefix=str -ddump-float-in -ddump-foreign -ddump-full-laziness -ddump-float-out -ddump-hie -ddump-hpc -ddump-if-trace -ddump-inlinings -ddump-js -ddump-json -ddump-late-cc -ddump-liberate-case -ddump-llvm -ddump-mod-map -ddump-occur-anal -ddump-opt-cmm -ddump-parsed -ddump-parsed-ast -ddump-prep -ddump-rn -ddump-rn-ast -ddump-rn-stats -ddump-rn-trace -ddump-rtti -ddump-rule-firings -ddump-rule-rewrites -ddump-rules -ddump-simpl -ddump-simpl-it- erations -ddump-simpl-stats -ddump-simpl-trace -ddump-spec -ddump-spec-constr -ddump-splices -ddump-static-argument-trans- formation -ddump-stg -ddump-stg-cg -ddump-stg-final -ddump-stg-from-core -ddump-stg-tags -ddump-stg-unarised -ddump-str-signatures -ddump-stranal -ddump-tc -ddump-tc-ast -ddump-tc-trace -ddump-ticked -ddump-timings -ddump-to-file -ddump-types -ddump-verbose-inlinings -ddump-view-pattern-com- moning -ddump-worker-wrapper -dfaststring-stats -dhex-word-lit- erals -dinitial-unique=s -dinline-check=str -dipe-stats -dkeep-comments -dlinear-core-lint -dlint -dno-debug-output -ddebug-output -dno-typeable-binds -dppr-case-as-let -dppr-cols=n -dppr-debug -dppr-user-length -drule-check=str -dshow-passes -dstg-lint -dsuppress-all -dsuppress-coer- cion-types -dsuppress-coercions -dsuppress-core-sizes -dsup- press-idinfo -dsuppress-module-prefixes -dsuppress-stg-free-vars -dsuppress-stg-reps -dsuppress-ticks -dsuppress-timestamps -dsuppress-type-applications -dsuppress-type-signatures -dsup- press-unfoldings -dsuppress-uniques -dsuppress-var-kinds -dtag-inference-checks -dth-dec-file -dunique-increment=i -dver- bose-core2core -dverbose-stg2stg -falignment-sanitisation -fcatch-nonexhaustive-cases -fcheck-prim-bounds -fcmm-thread-sanitizer -fdistinct-constructor-tables -fdump-with-ways -finfo-table-map -finfo-table-map-with-fallback -fno-info-table-map-with-fallback -finfo-table-map-with-stack -fno-info-table-map-with-stack -fllvm-fill-undef-with-garbage -fno-info-table-map-with-fallback -finfo-table-map-with-fallback -fno-info-table-map-with-stack -finfo-table-map-with-stack -forig-thunk-info -fproc-alignment -funoptimized-core-for-inter- preter -fno-unoptimized-core-for-interpreter -g -gn C pre-processor -cpp -Dsymbol[=value] -Usymbol -Idir -Usymbol Finding imports -i -idir[:dir]* Interactive mode -fbreak-on-error -fno-break-on-error -fbreak-on-exception -fno-break-on-exception -fbreak-points -fno-break-points -fghci-hist-size=n -fghci-leak-check -fno-ghci-leak-check -fim- plicit-import-qualified -fno-implicit-import-qualified -flo- cal-ghci-history -fno-local-ghci-history -fno-it -fno-no-it -fprint-bind-result -fno-print-bind-result -fprint-evld-with-show -fshow-loaded-modules -ghci-script -ig- nore-dot-ghci -no-ignore-dot-ghci -interactive-print name Interface files --show-iface file -ddump-hi -ddump-hi-diffs -ddump-minimal-im- ports Keeping intermediate files -keep-hc-file -keep-hc-files -keep-hi-files -no-keep-hi-files -keep-hscpp-file -keep-hscpp-files -keep-llvm-file -keep-llvm-files -keep-o-files -no-keep-o-files -keep-s-file -keep-s-files -keep-tmp-files Language options -XAllowAmbiguousTypes -XApplicativeDo -XArrows -XBangPatterns -XBinaryLiterals -XBlockArguments -XCApiFFI -XConstrainedClass- Methods -XConstraintKinds -XCPP -XCUSKs -XDataKinds -XDatatype- Contexts -XDeepSubsumption -XDefaultSignatures -XDeriveAnyClass -XDeriveDataTypeable -XDeriveFoldable -XDeriveFunctor -XDeriveG- eneric -XDeriveLift -XDeriveTraversable -XDerivingStrategies -XDerivingVia -XDisambiguateRecordFields -XDuplicateRecordFields -XEmptyCase -XEmptyDataDecls -XEmptyDataDeriving -XExisten- tialQuantification -XExplicitForAll -XExplicitNamespaces -XEx- tendedDefaultRules -XExtendedLiterals -XFieldSelectors -XFlexi- bleContexts -XFlexibleInstances -XForeignFunctionInterface -XFunctionalDependencies -XGADTs -XGADTSyntax -XGeneralisedNew- typeDeriving -XGeneralizedNewtypeDeriving -XGHC2021 -XGHC2024 -XGHCForeignImportPrim -XHaskell2010 -XHaskell98 -XHexFloatLit- erals -XImplicitParams -XImportQualifiedPost -XImpredica- tiveTypes -XIncoherentInstances -XInstanceSigs -XInterrupt- ibleFFI -XKindSignatures -XLambdaCase -XLexicalNegation -XLiber- alTypeSynonyms -XLinearTypes -XListTuplePuns -XMagicHash -XMon- adComprehensions -XMonoLocalBinds -XMultiParamTypeClasses -XMul- tiWayIf -XNamedFieldPuns -XNamedWildCards -XNegativeLiterals -XNoImplicitPrelude -XNoMonomorphismRestriction -XNonde- creasingIndentation -XNoPatternGuards -XNoTraditionalRecordSyn- tax -XNPlusKPatterns -XNullaryTypeClasses -XNumDecimals -XNumer- icUnderscores -XOverlappingInstances -XOverloadedLabels -XOver- loadedLists -XOverloadedRecordDot -XOverloadedRecordUpdate -XOverloadedStrings -XPackageImports -XParallelListComp -XPar- tialTypeSignatures -XPatternSynonyms -XPolyKinds -XPostfixOpera- tors -XQualifiedDo -XQuantifiedConstraints -XQuasiQuotes -XRank2Types -XRankNTypes -XRebindableSyntax -XRecordWildCards -XRecursiveDo -XRequiredTypeArguments -XRoleAnnotations -XSafe -XScopedTypeVariables -XStandaloneDeriving -XStandaloneKindSig- natures -XStarIsType -XStaticPointers -XStrict -XStrictData -XTemplateHaskell -XTemplateHaskellQuotes -XTransformListComp -XTrustworthy -XTupleSections -XTypeAbstractions -XTypeApplica- tions -XTypeData -XTypeFamilies -XTypeFamilyDependencies -XType- InType -XTypeOperators -XTypeSynonymInstances -XUnboxedSums -XUnboxedTuples -XUndecidableInstances -XUndecidableSuperClasses -XUnicodeSyntax -XUnliftedDatatypes -XUnliftedFFITypes -XUnlift- edNewtypes -XUnsafe -XViewPatterns Linking options -c -debug -dylib-install-name path -dynamic -dynload -eventlog -fcompact-unwind -fkeep-cafs -flink-rts -fno-embed-manifest -fno-gen-manifest -fno-shared-implib -framework name -frame- work-path dir -fsplit-sections -split-sections -fno-split-sec- tions -fuse-rpaths -fwhole-archive-hs-libs -L dir -l lib -main-is thing -no-hs-main -no-pie -pie -no-rtsopts-suggestions -package name -pie -no-pie -rdynamic -rtsopts[=none|some|all|ig- nore|ignoreAll] -shared -single-threaded -threaded -static -sta- ticlib -threaded -single-threaded -with-rtsopts=opts Miscellaneous options -ddump-mod-cycles -fdefer-out-of-scope-variables -fno-de- fer-out-of-scope-variables -fdefer-type-errors -fno-de- fer-type-errors -fdefer-typed-holes -fno-defer-typed-holes -fex- ternal-interpreter -ffamily-application-cache -fno-family-appli- cation-cache -fglasgow-exts -fno-glasgow-exts -fno-safe-haskell -ghcversion-file path to ghcversion.h -H size -hidden-module module name -j[n] -jsem -reexported-module module name -this-package-name unit-id -unit @filename -working-dir dir Modes of operation --frontend module --help -? --info --interactive --make --nu- meric-version --print-booter-version --print-build-platform --print-c-compiler-flags --print-c-compiler-link-flags --print-debug-on --print-global-package-db --print-have-inter- preter --print-have-native-code-generator --print-host-platform --print-ld-flags --print-leading-underscore --print-libdir --print-object-splitting-supported --print-project-git-commit-id --print-project-version --print-rts-ways --print-stage --print-support-smp --print-tables-next-to-code --print-tar- get-platform --print-unregisterised --run file --show-iface file --show-options --supported-extensions --supported-languages --version -V -e expr -M -shared Individual optimizations -fasm-shortcutting -fno-asm-shortcutting -fbinary-blob-thresh- old=n -fblock-layout-cfg -fno-block-layout-cfg -fblock-lay- out-weightless -fno-block-layout-weightless -fblock-lay- out-weights -fcall-arity -fno-call-arity -fcase-folding -fno-case-folding -fcase-merge -fno-case-merge -fcmm-con- trol-flow -fno-cmm-control-flow -fcmm-elim-common-blocks -fno-cmm-elim-common-blocks -fcmm-sink -fno-cmm-sink -fcmm-sta- tic-pred -fno-cmm-static-pred -fcore-constant-folding -fno-core-constant-folding -fcpr-anal -fno-cpr-anal -fcross-mod- ule-specialise -fno-cross-module-specialise -fcse -fno-cse -fdicts-cheap -fno-dicts-cheap -fdicts-strict -fno-dicts-strict -fdmd-tx-dict-sel -fno-dmd-tx-dict-sel -fdmd-unbox-width=n -fdo-clever-arg-eta-expansion -fno-do-clever-arg-eta-expansion -fdo-eta-reduction -fno-do-eta-reduction -fdo-lambda-eta-expan- sion -fno-do-lambda-eta-expansion -feager-blackholing -fen- able-rewrite-rules -fno-enable-rewrite-rules -fexcess-precision -fno-excess-precision -fexitification -fno-exitification -fex- pose-all-unfoldings -fno-expose-all-unfoldings -ffloat-in -fno-float-in -ffull-laziness -fno-full-laziness -ffun-to-thunk -fno-fun-to-thunk -fignore-asserts -fno-ignore-asserts -fig- nore-interface-pragmas -fno-ignore-interface-pragmas -fin- line-generics -fno-inline-generics -finline-generics-aggres- sively -fno-inline-generics-aggressively -finter-mod- ule-far-jumps -fno-inter-module-far-jumps -fkeep-auto-rules -fno-keep-auto-rules -flate-dmd-anal -fno-late-dmd-anal -flate-specialise -fno-late-specialise -fliberate-case -fno-lib- erate-case -fliberate-case-threshold=n -fno-liber- ate-case-threshold -fllvm-pass-vectors-in-regs -flocal-float-out -fno-local-float-out -flocal-float-out-top-level -fno-lo- cal-float-out-top-level -floopification -fno-loopification -fmax-forced-spec-args=n -fmax-inline-alloc-size=n -fmax-in- line-memcpy-insns=n -fmax-inline-memset-insns=n -fmax-simpli- fier-iterations=n -fmax-uncovered-patterns=n -fmax-worker-args=n -fno-opt-coercion -fno-pre-inlining -fno-state-hack -fomit-in- terface-pragmas -fno-omit-interface-pragmas -fomit-yields -fno-omit-yields -foptimal-applicative-do -fno-optimal-applica- tive-do -fpedantic-bottoms -fno-pedantic-bottoms -fpolymor- phic-specialisation -fno-polymorphic-specialisation -fregs-graph -fno-regs-graph -fregs-iterative -fno-regs-iterative -fsimpl-tick-factor=n -fsimplifier-phases=n -fsolve-con- stant-dicts -fno-solve-constant-dicts -fspec-constr -fno-spec-constr -fspec-constr-count=n -fno-spec-constr-count -fspec-constr-keen -fno-spec-constr-keen -fspec-constr-thresh- old=n -fno-spec-constr-threshold -fspec-eval -fno-spec-eval -fspec-eval-dictfun -fno-spec-eval-dictfun -fspecialise -fno-specialise -fspecialise-aggressively -fno-specialise-ag- gressively -fspecialise-incoherents -fno-specialise-incoherents -fstatic-argument-transformation -fno-static-argument-transfor- mation -fstg-cse -fno-stg-cse -fstg-lift-lams -fno-stg-lift-lams -fstg-lift-lams-known -fno-stg-lift-lams-known -fstg-lift-lams-non-rec-args -fstg-lift-lams-non-rec-args-any -fstg-lift-lams-rec-args -fstg-lift-lams-rec-args-any -fstrict- ness -fno-strictness -fstrictness-before=n -fun- box-small-strict-fields -fno-unbox-small-strict-fields -fun- box-strict-fields -fno-unbox-strict-fields -funfold- ing-case-scaling=n -funfolding-case-threshold=n -funfolding-cre- ation-threshold=n -funfolding-dict-discount=n -funfold- ing-fun-discount=n -funfolding-keeness-factor=n -funfold- ing-use-threshold=n -fworker-wrapper -fworker-wrapper-cbv Optimization levels -O -O1 -O0 -O0 -O2 -O0 -On -O0 Package options -clear-package-db -distrust pkg -distrust-all-packages -fpack- age-trust -global-package-db -hide-all-packages -hide-package pkg -ignore-package pkg -no-auto-link-packages -no-global-pack- age-db -no-user-package-db -package pkg -package-db file -pack- age-env file|name -package-id unit-id -this-unit-id unit-id -trust pkg -user-package-db Phases of compilation --merge-objs -C -c -E -F -S -x suffix Overriding external programs -pgma cmd -pgmc cmd -pgmCmmP cmd -pgmcxx cmd -pgmF cmd -pgmi cmd -pgminstall_name_tool cmd -pgmJSP cmd -pgmL cmd -pgml cmd -pgm- las cmd -pgmlc cmd -pgmlm cmd -pgmlo cmd -pgmotool cmd -pgmP cmd -pgms cmd -pgmwindres cmd Phase-specific options -opta option -optc option -optCmmP option -optcxx option -optF option -opti option -optJSP option -optL option -optl option -optlas option -optlc option -optlm option -optlo option -optP option -optwindres option -pgmc-supports-no-pie -pgml-sup- ports-no-pie Platform-specific options -mavx -mavx2 -mavx512cd -mavx512er -mavx512f -mavx512pf -mbmi -mbmi2 -mfma -msse -msse2 -msse3 -msse4 -msse4.2 Compiler plugins -fclear-plugins -fplugin-library=file-path;unit-id;module;args -fplugin-opt=module:args -fplugin-trustworthy -fplugin=module -hide-all-plugin-packages -plugin-package pkg -plugin-package-id pkg-id Profiling -auto -auto-all -caf-all -fno-prof-count-entries -fprof-count-entries -fprof-auto -fno-prof-auto -fprof-auto-calls -fno-prof-auto -fprof-auto-exported -fno-prof-auto -fprof-auto-top -fno-prof-auto -fprof-cafs -fno-prof-cafs -fprof-callers=name -fprof-late -fno-prof-late -fprof-late-inline -fno-prof-late-inline -fprof-late-overloaded -fno-prof-late-overloaded -fprof-late-overloaded-calls -fno-prof-late-overloaded-calls -fprof-manual -fno-prof-manual -no-auto -no-auto-all -no-caf-all -prof -ticky -ticky-allocd -ticky-ap-thunk -ticky-dyn-thunk -ticky-LNE -ticky-tag-checks Program coverage -fhpc -hpcdirdir Recompilation checking -exclude-module=file -fforce-recomp -fno-force-recomp -fig- nore-hpc-changes -fno-ignore-hpc-changes -fignore-optim-changes -fno-ignore-optim-changes -include-cpp-deps -include-pkg-deps Redirecting output -dep-makefile file -dep-suffix suffix -dumpdir dir -dynhisuf suffix -dyno file -dynohi file -dynosuf suffix -hcsuf suffix -hidir dir -hiedir dir -hiesuf suffix -hisuf suffix -o file -odir dir -ohi file -osuf suffix -outputdir dir -stubdir dir Temporary files -tmpdir dir Verbosity options -fabstract-refinement-hole-fits -fno-abstract-refine- ment-hole-fits -fdefer-diagnostics -fdiagnostics-as-json -fdiag- nostics-color=always|auto|never -fdiagnostics-show-caret -fno-diagnostics-show-caret -ferror-spans -fhide-source-paths -fkeep-going -fmax-refinement-hole-fits=n -fno-max-refine- ment-hole-fits -fmax-relevant-binds=n -fno-max-relevant-binds -fmax-valid-hole-fits=n -fno-max-valid-hole-fits -fno-show-valid-hole-fits -fno-sort-valid-hole-fits -fsort-valid-hole-fits -fprint-axiom-incomps -fno-print-ax- iom-incomps -fprint-equality-relations -fno-print-equality-rela- tions -fprint-error-index-links=always|auto|never -fprint-ex- panded-synonyms -fno-print-expanded-synonyms -fprint-ex- plicit-coercions -fno-print-explicit-coercions -fprint-ex- plicit-foralls -fno-print-explicit-foralls -fprint-ex- plicit-kinds -fno-print-explicit-kinds -fprint-explicit-run- time-reps -fno-print-explicit-runtime-reps -fprint-potential-in- stances -fno-print-potential-instances -fprint-redundant-promo- tion-ticks -fno-print-redundant-promotion-ticks -fprint-type- checker-elaboration -fno-print-typechecker-elaboration -fprint-unicode-syntax -fno-print-unicode-syntax -frefine- ment-level-hole-fits=n -fno-refinement-level-hole-fits -fre- verse-errors -fno-reverse-errors -fshow-docs-of-hole-fits -fno-show-docs-of-hole-fits -fshow-error-context -fno-show-er- ror-context -fshow-hole-constraints -fshow-hole-matches-of-hole-fits -fno-show-hole-matches-of-hole-fits -fshow-prove- nance-of-hole-fits -fno-show-provenance-of-hole-fits -fshow-type-app-of-hole-fits -fno-show-type-app-of-hole-fits -fshow-type-app-vars-of-hole-fits -fno-show-type-app-vars-of-hole-fits -fshow-type-of-hole-fits -fno-show-type-of-hole-fits -fsort-by-size-hole-fits -fno-sort-by-size-hole-fits -fsort-by-subsumption-hole-fits -fno-sort-by-subsumption-hole-fits -funclutter-valid-hole-fits -Rghc-timing -v -vn Warnings -fenable-th-splice-warnings -fno-enable-th-splice-warnings -fhelpful-errors -fno-helpful-errors -fmax-pmcheck-models=n -fshow-warning-groups -fno-show-warning-groups -fvia-C -W -Wno-extra -w -Wall -Wno-all -Wall-missed-specialisations -Wno-all-missed-specialisations -Wall-missed-specializations -Wno-all-missed-specializations -Wambiguous-fields -Wauto-or- phans -Wbadly-staged-types -Wno-badly-staged-types -Wcompat -Wno-compat -Wcompat-unqualified-imports -Wno-compat-unquali- fied-imports -Wcpp-undef -Wdata-kinds-tc -Wno-data-kinds-tc -Wdefault -Wno-default -Wdefaulted-exception-context -Wnop-de- faulted-exception-context -Wdeferred-out-of-scope-variables -Wno-deferred-out-of-scope-variables -Wdeferred-type-errors -Wno-deferred-type-errors -Wdeprecated-flags -Wno-depre- cated-flags -Wdeprecated-type-abstractions -Wno-depre- cated-type-abstractions -Wdeprecations -Wno-deprecations -Wderiving-defaults -Wno-deriving-defaults -Wderiving-typeable -Wno-deriving-typeable -Wdodgy-exports -Wno-dodgy-exports -Wdodgy-foreign-imports -Wno-dodgy-foreign-imports -Wdodgy-im- ports -Wno-dodgy-imports -Wduplicate-constraints -Wno-dupli- cate-constraints -Wduplicate-exports -Wno-duplicate-exports -Wempty-enumerations -Wno-empty-enumerations -Werror -Wwarn -Weverything -w -Wextended-warnings -Wno-extended-warnings -Wex- tra -Wno-extra -Wforall-identifier -Wgadt-mono-local-binds -Wno-gadt-mono-local-binds -Whi-shadowing -Wno-hi-shadowing -Widentities -Wno-identities -Wimplicit-kind-vars -Wno-im- plicit-kind-vars -Wimplicit-lift -Wno-implicit-lift -Wim- plicit-prelude -Wno-implicit-prelude -Wimplicit-rhs-quantifica- tion -Wno-implicit-rhs-quantification -Winaccessible-code -Wno-inaccessible-code -Wincomplete-export-warnings -Wno-incom- plete-export-warnings -Wincomplete-patterns -Wno-incomplete-pat- terns -Wincomplete-record-selectors -Wno-incomplete-record-se- lectors -Wincomplete-record-updates -Wno-incomplete-record-up- dates -Wincomplete-uni-patterns -Wno-incomplete-uni-patterns -Winconsistent-flags -Wno-inconsistent-flags -Winferred-safe-im- ports -Wno-inferred-safe-imports -Winline-rule-shadowing -Wno-inline-rule-shadowing -Winvalid-haddock -Wno-invalid-had- dock -Wloopy-superclass-solve -Wno-loopy-superclass-solve -Wmis- placed-pragmas -Wno-misplaced-pragmas -Wmissed-extra-shared-lib -Wno-missed-extra-shared-lib -Wmissed-specialisations -Wno-missed-specialisations -Wmissed-specializations -Wno-missed-specializations -Wmissing-deriving-strategies -Wno-missing-deriving-strategies -Wmissing-export-lists -Wno-missing-export-lists -Wmissing-exported-pattern-syn- onym-signatures -Wno-missing-exported-pattern-synonym-signatures -Wmissing-exported-signatures -Wno-missing-exported-signatures -Wmissing-exported-sigs -Wno-missing-exported-sigs -Wmiss- ing-fields -Wno-missing-fields -Wmissing-home-modules -Wno-miss- ing-home-modules -Wmissing-import-lists -Wno-missing-im- port-lists -Wmissing-kind-signatures -Wno-missing-kind-signa- tures -Wmissing-local-signatures -Wno-missing-local-signatures -Wmissing-local-sigs -Wno-missing-local-sigs -Wmissing-methods -Wno-missing-methods -Wmissing-monadfail-instances -Wno-miss- ing-monadfail-instances -Wmissing-pattern-synonym-signatures -Wno-missing-pattern-synonym-signatures -Wmissing-poly-kind-sig- natures -Wno-missing-poly-kind-signatures -Wmissing-role-annota- tions -Wno-role-annotations-signatures -Wmiss- ing-safe-haskell-mode -Wno-missing-safe-haskell-mode -Wmiss- ing-signatures -Wno-missing-signatures -Wmissing-space-af- ter-bang -Wmonomorphism-restriction -Wno-monomorphism-restric- tion -Wname-shadowing -Wno-name-shadowing -Wnoncanoni- cal-monad-instances -Wno-noncanonical-monad-instances -Wnon- canonical-monadfail-instances -Wno-noncanonical-monadfail-in- stances -Wnoncanonical-monoid-instances -Wno-noncanoni- cal-monoid-instances -Wnot -Woperator-whitespace -Wno-opera- tor-whitespace -Woperator-whitespace-ext-conflict -Wno-opera- tor-whitespace-ext-conflict -Worphans -Wno-orphans -Wover- flowed-literals -Wno-overflowed-literals -Woverlapping-patterns -Wno-overlapping-patterns -Wpartial-fields -Wno-partial-fields -Wpartial-type-signatures -Wno-partial-type-signatures -Wprepos- itive-qualified-module -Wno-prepositive-qualified-module -Wre- dundant-bang-patterns -Wno-redundant-bang-patterns -Wredun- dant-constraints -Wno-redundant-constraints -Wredun- dant-record-wildcards -Wno-redundant-record-wildcards -Wredun- dant-strictness-flags -Wno-redundant-strictness-flags -Wsafe -Wno-safe -Wsemigroup -Wno-semigroup -Wsimplifiable-class-con- straints -Wno-simplifiable-class-constraints -Wstar-binder -Wno-star-binder -Wstar-is-type -Wno-star-is-type -Wtabs -Wno-tabs -Wterm-variable-capture -Wtrustworthy-safe -Wno-safe -Wtype-defaults -Wno-type-defaults -Wtype-equality-out-of-scope -Wno-type-equality-out-of-scope -Wtype-equality-requires-opera- tors -Wno-type-equality-requires-operators -Wtyped-holes -Wno-typed-holes -Wunbanged-strict-patterns -Wno-un- banged-strict-patterns -Wunicode-bidirectional-format-characters -Wunrecognised-pragmas -Wno-unrecognised-pragmas -Wunrecog- nised-warning-flags -Wno-unrecognised-warning-flags -Wunsafe -Wno-unsafe -Wunsupported-calling-conventions -Wno-unsup- ported-calling-conventions -Wunsupported-llvm-version -Wno-un- supported-llvm-version -Wunticked-promoted-constructors -Wno-unticked-promoted-constructors -Wunused-binds -Wno-un- used-binds -Wunused-do-bind -Wno-unused-do-bind -Wunused-foralls -Wno-unused-foralls -Wunused-imports -Wno-unused-imports -Wunused-local-binds -Wno-unused-local-binds -Wunused-matches -Wno-unused-matches -Wunused-packages -Wno-unused-packages -Wunused-pattern-binds -Wno-unused-pattern-binds -Wunused-record-wildcards -Wno-unused-record-wildcards -Wunused-top-binds -Wno-unused-top-binds -Wunused-type-patterns -Wno-unused-type-patterns -Wwarn -Werror -Wwarnings-deprecations -Wno-warnings-deprecations -Wwrong-do-bind -Wno-wrong-do-bind -Wx-category -Wno-x-category Code generation -dynamic-too Build dynamic object files as well as static object files during compilation -fasm Use the native code generator -fbyte-code Generate byte-code -fbyte-code-and-object-code Generate object code and byte-code -fexpose-internal-symbols Produce symbols for all functions, including internal functions. -fexternal-dynamic-refs Generate code for linking against dynamic libraries -fllvm Compile using the LLVM code generator -fno-code Omit code generation -fobject-code Generate object code -fPIC Generate position-independent code (where available) -fPIE Generate code for a position-independent executable (where available) -fprefer-byte-code Use byte-code if it is available to evaluate TH splices -fwrite-if-simplified-core Write an interface file containing the simplified core of the module. -fwrite-interface Always write interface files Debugging the compiler -dasm-lint ASM pass sanity checking -dcmm-lint C-\- pass sanity checking -dcore-lint Turn on internal sanity checking -ddisable-js-c-sources Disable the link with C sources compiled to JavaScript -ddisable-js-minifier Generate pretty-printed JavaScript code instead of minified (compacted) code. -ddump-asm Dump final assembly -ddump-asm-conflicts Dump register conflicts from the register allocator. -ddump-asm-liveness Dump assembly augmented with register liveness -ddump-asm-native Dump initial assembly -ddump-asm-regalloc Dump the result of register allocation -ddump-asm-regalloc-stages Dump the build/spill stages of the -fregs-graph register alloca- tor. -ddump-asm-stats Dump statistics from the register allocator. -ddump-bcos Dump interpreter byte code -ddump-c-backend Dump C code produced by the C (unregisterised) backend. -ddump-call-arity Dump output of the call arity analysis pass. -ddump-cfg-weights Dump the assumed weights of the CFG. -ddump-cmm Dump the final C-\- output -ddump-cmm-caf Dump the results of the C-\- CAF analysis pass. -ddump-cmm-cbe Dump the results of common block elimination -ddump-cmm-cfg Dump the results of the C-\- control flow optimisation pass. -ddump-cmm-cps Dump the results of the CPS pass -ddump-cmm-from-stg Dump STG-to-C-\- output -ddump-cmm-info Dump the results of the C-\- info table augmentation pass. -ddump-cmm-opt Dump the results of C-\- to C-\- optimising passes -ddump-cmm-proc Dump the results of proc-point analysis -ddump-cmm-procmap Dump the results of the C-\- proc-point map pass. -ddump-cmm-raw Dump raw C-\- -ddump-cmm-sink Dump the results of the C-\- sinking pass. -ddump-cmm-sp Dump the results of the C-\- stack layout pass. -ddump-cmm-split Dump the results of the C-\- proc-point splitting pass. -ddump-cmm-switch Dump the results of switch lowering passes -ddump-cmm-thread-sanitizer Dump the results of the C-\- ThreadSanitizer elaboration pass. -ddump-cmm-verbose Write output from main C-\- pipeline passes to files -ddump-cmm-verbose-by-proc Show output from main C-\- pipeline passes (grouped by proc) -ddump-core-stats Print a one-line summary of the size of the Core program at the end of the optimisation pipeline -ddump-cpr-signatures Dump CPR signatures -ddump-cpranal Dump CPR analysis output -ddump-cs-trace Trace constraint solver -ddump-cse Dump CSE output -ddump-debug Dump generated DWARF debug information -ddump-deriv Dump deriving output -ddump-dmd-signatures Dump top-level demand signatures -ddump-dmdanal Dump demand analysis output -ddump-ds Dump desugarer output. -ddump-ec-trace Trace exhaustiveness checker -ddump-exitify Dump output of the exitification pass. -ddump-faststrings Dump the whole FastString table when finished -ddump-file-prefix=str Set the prefix of the filenames used for debugging output. -ddump-float-in Dump float in output -ddump-foreign Dump foreign export stubs -ddump-full-laziness Dump full laziness pass output -ddump-hie Dump the hie file syntax tree -ddump-hpc An alias for -ddump-ticked. -ddump-if-trace Trace interface files -ddump-inlinings Dump inlinings performed by the simplifier. -ddump-js Dump final JavaScript code -ddump-json (deprecated) Use -fdiagnostics-as-json instead -ddump-late-cc Dump core with late cost centres added -ddump-liberate-case Dump liberate case output -ddump-llvm Dump LLVM intermediate code. -ddump-mod-map Dump the state of the module mapping database. -ddump-occur-anal Dump occurrence analysis output -ddump-opt-cmm Dump the results of C-\- to C-\- optimising passes -ddump-parsed Dump parse tree -ddump-parsed-ast Dump parser output as a syntax tree -ddump-prep Dump prepared core -ddump-rn Dump renamer output -ddump-rn-ast Dump renamer output as a syntax tree -ddump-rn-stats Renamer stats -ddump-rn-trace Trace renamer -ddump-rtti Trace runtime type inference -ddump-rule-firings Dump rule firing info -ddump-rule-rewrites Dump detailed rule firing info -ddump-rules Dump rewrite rules -ddump-simpl Dump final simplifier output -ddump-simpl-iterations Dump output from each simplifier iteration -ddump-simpl-stats Dump simplifier stats -ddump-simpl-trace Dump trace messages in simplifier -ddump-spec Dump specialiser output -ddump-spec-constr Dump specialiser output from SpecConstr -ddump-splices Dump TH spliced expressions, and what they evaluate to -ddump-static-argument-transformation Dump static argument transformation output -ddump-stg (deprecated) Alias for -ddump-stg-from-core -ddump-stg-cg Show output after Stg2Stg -ddump-stg-final Show output of last STG pass. -ddump-stg-from-core Show CoreToStg output -ddump-stg-tags Show output of the tag inference pass. -ddump-stg-unarised Show unarised STG -ddump-str-signatures (deprecated) Alias for -ddump-dmd-signatures -ddump-stranal (deprecated) Alias for -ddump-dmdanal -ddump-tc Dump typechecker output -ddump-tc-ast Dump typechecker output as a syntax tree -ddump-tc-trace Trace typechecker -ddump-ticked Dump the code instrumented by HPC (Observing Code Coverage). -ddump-timings Dump per-pass timing and allocation statistics -ddump-to-file Dump to files instead of stdout -ddump-types Dump type signatures -ddump-verbose-inlinings Dump all considered inlinings -ddump-view-pattern-commoning Dump commoned view patterns -ddump-worker-wrapper Dump worker-wrapper output -dfaststring-stats Show statistics for fast string usage when finished -dhex-word-literals Print values of type Word# in hexadecimal. -dinitial-unique=s Start UniqSupply allocation from s. -dinline-check=str Dump information about inlining decisions -dipe-stats Show statistics about IPE information -dkeep-comments Include comments in the parser. Useful in combination with -ddump-parsed-ast. -dlinear-core-lint Turn on internal sanity checking -dlint Enable several common internal sanity checkers -dno-debug-output Suppress unsolicited debugging output -dno-typeable-binds Don't generate bindings for Typeable methods -dppr-case-as-let Print single alternative case expressions as strict lets. -dppr-cols=n Set the width of debugging output. For example -dppr-cols200 -dppr-debug Turn on debug printing (more verbose) -dppr-user-length Set the depth for printing expressions in error msgs -drule-check=str Dump information about potential rule application -dshow-passes Print out each pass name as it happens -dstg-lint STG pass sanity checking -dsuppress-all In dumps, suppress everything (except for uniques) that is sup- pressible. -dsuppress-coercion-types Suppress the printing of coercion types in Core dumps to make them shorter -dsuppress-coercions Suppress the printing of coercions in Core dumps to make them shorter -dsuppress-core-sizes Suppress the printing of core size stats per binding (since 9.4) -dsuppress-idinfo Suppress extended information about identifiers where they are bound -dsuppress-module-prefixes Suppress the printing of module qualification prefixes -dsuppress-stg-free-vars Suppress the printing of closure free variable lists in STG out- put -dsuppress-stg-reps Suppress rep annotations on STG args. -dsuppress-ticks Suppress "ticks" in the pretty-printer output. -dsuppress-timestamps Suppress timestamps in dumps -dsuppress-type-applications Suppress type applications -dsuppress-type-signatures Suppress type signatures -dsuppress-unfoldings Suppress the printing of the stable unfolding of a variable at its binding site -dsuppress-uniques Suppress the printing of uniques in debug output (easier to use diff) -dsuppress-var-kinds Suppress the printing of variable kinds -dtag-inference-checks Affirm tag inference results are correct at runtime. -dth-dec-file Dump evaluated TH declarations into *.th.hs files -dunique-increment=i Set the increment for the generated Unique's to i. -dverbose-core2core Show output from each core-to-core pass -dverbose-stg2stg Show output from each STG-to-STG pass -falignment-sanitisation Compile with alignment checks for all info table dereferences. -fcatch-nonexhaustive-cases Add a default error alternative to case expressions without a default alternative. -fcheck-prim-bounds Instrument array primops with bounds checks. -fcmm-thread-sanitizer Enable ThreadSanitizer instrumentation of memory accesses. -fdistinct-constructor-tables Generate a fresh info table for each usage of a data construc- tor. -fdump-with-ways Include the tag of the enabled ways in the extension of dump files. -finfo-table-map Embed a lookup table in the generated binary which maps the ad- dress of an info table to the source position the closure origi- nated from. -finfo-table-map-with-fallback Include info tables with no source location information in the info table map. -finfo-table-map-with-stack Include info tables for STACK closures in the info table map. -fllvm-fill-undef-with-garbage Intruct LLVM to fill dead STG registers with garbage -fno-info-table-map-with-fallback Omit info tables with no source location information from the info table map. -fno-info-table-map-with-stack Omit info tables for STACK closures from the info table map. -forig-thunk-info Generate stg_orig_thunk_info stack frames on thunk entry -fproc-alignment Align functions at given boundary. -funoptimized-core-for-interpreter Disable optimizations with the interpreter -g Produce DWARF debug information in compiled object files. n can be 0, 1, or 2, with higher numbers producing richer output. If n is omitted, level 2 is assumed. C pre-processor -cpp Run the C pre-processor on Haskell source files -Dsymbol[=value] Define a symbol in the C pre-processor -Idir Add dir to the directory search list for #include files -Usymbol Undefine a symbol in the C pre-processor Finding imports -i Empty the import directory list -idir[:dir]* add dir, dir2, etc. to import path Interactive mode -fbreak-on-error Break on uncaught exceptions and errors -fbreak-on-exception Break on any exception thrown -fbreak-points Insert breakpoints in the GHCi debugger -fghci-hist-size=n Set the number of entries GHCi keeps for :history. See The GHCi Debugger. -fghci-leak-check (Debugging only) check for space leaks when loading new modules in GHCi. -fimplicit-import-qualified Put in scope qualified identifiers for every loaded module -flocal-ghci-history Use current directory for the GHCi command history file .ghci-history. -fno-it No longer set the special variable it. -fprint-bind-result Turn on printing of binding results in GHCi -fprint-evld-with-show Instruct :print to use Show instances where possible. -fshow-loaded-modules Show the names of modules that GHCi loaded after a :load com- mand. -ghci-script Read additional .ghci files -ignore-dot-ghci Disable reading of .ghci files -interactive-print name Select the function to use for printing evaluated expressions in GHCi Interface files --show-iface file See Modes of operation. -ddump-hi Dump the new interface to stdout -ddump-hi-diffs Show the differences vs. the old interface -ddump-minimal-imports Dump a minimal set of imports Keeping intermediate files -keep-hc-file Retain intermediate .hc files. -keep-hi-files Retain intermediate .hi files (the default). -keep-hscpp-file Retain intermediate .hscpp files. -keep-llvm-file Retain intermediate LLVM .ll files. Implies -fllvm. -keep-o-files Retain intermediate .o files (the default). -keep-s-file Retain intermediate .s files. -keep-tmp-files Retain all intermediate temporary files. Language options -XAllowAmbiguousTypes Allow the user to write ambiguous types, and the type inference engine to infer them. -XApplicativeDo Enable Applicative do-notation desugaring -XArrows Enable arrow notation extension -XBangPatterns Enable bang patterns. -XBinaryLiterals Enable support for binary literals. -XBlockArguments Allow do blocks and other constructs as function arguments. -XCApiFFI Enable the CAPI calling convention. -XConstrainedClassMethods Enable constrained class methods. Implied by MultiParamTypeClasses. -XConstraintKinds Enable a kind of constraints. -XCPP Enable the C preprocessor. -XCUSKs Enable detection of complete user-supplied kind signatures. -XDataKinds Enable datatype promotion. -XDatatypeContexts Allow contexts on data types. -XDeepSubsumption Enable deep subsumption -XDefaultSignatures Enable default signatures. -XDeriveAnyClass Enable deriving for any class. -XDeriveDataTypeable Enable deriving for the Data class. -XDeriveFoldable Enable deriving for the Foldable class. Implied by DeriveTraversable. -XDeriveFunctor Enable deriving for the Functor class. Implied by DeriveTraversable. -XDeriveGeneric Enable deriving for the Generic class. -XDeriveLift Enable deriving for the Lift class -XDeriveTraversable Enable deriving for the Traversable class. Implies DeriveFunctor and DeriveFoldable. -XDerivingStrategies Enables deriving strategies. -XDerivingVia Enable deriving instances via types of the same runtime repre- sentation. Implies DerivingStrategies. -XDisambiguateRecordFields Enable record field disambiguation. Implied by RecordWildCards. -XDuplicateRecordFields Allow definition of record types with identically-named fields. -XEmptyCase Allow empty case alternatives. -XEmptyDataDecls Allow definition of empty data types. -XEmptyDataDeriving Allow deriving instances of standard type classes for empty data types. -XExistentialQuantification Enable liberalised type synonyms. -XExplicitForAll Enable explicit universal quantification. Implied by ScopedTypeVariables, LiberalTypeSynonyms, RankNTypes and ExistentialQuantification. -XExplicitNamespaces Enable using the keyword type to specify the namespace of en- tries in imports and exports (Explicit namespaces in import/ex- port). Implied by TypeOperators and TypeFamilies. -XExtendedDefaultRules Use GHCi's extended default rules in a normal module. -XExtendedLiterals Enable numeric literal postfix syntax for unboxed integers. -XFieldSelectors Control visibility of field selector functions. -XFlexibleContexts Remove some restrictions on class contexts -XFlexibleInstances Enable flexible instances. Implies TypeSynonymInstances. -XForeignFunctionInterface Enable foreign function interface. -XFunctionalDependencies Enable functional dependencies. Implies MultiParamTypeClasses. -XGADTs Enable generalised algebraic data types. Implies GADTSyntax and MonoLocalBinds. -XGADTSyntax Enable generalised algebraic data type syntax. -XGeneralisedNewtypeDeriving Enable newtype deriving. -XGeneralizedNewtypeDeriving Enable newtype deriving. -XGHC2021 Use GHCs set of default language extensions from 2021 -XGHC2024 Use GHCs set of default language extensions from 2024 -XGHCForeignImportPrim Enable prim calling convention. Intended for internal use only. -XHaskell2010 Use the Haskell 2010 language edition. -XHaskell98 Use the Haskell 98 language edition. -XHexFloatLiterals Enable support for hexadecimal floating point literals. -XImplicitParams Enable Implicit Parameters. -XImportQualifiedPost ImportQualifiedPost allows the syntax import M qualified -XImpredicativeTypes Enable impredicative types. Implies RankNTypes. -XIncoherentInstances Enable incoherent instances. Implies OverlappingInstances. -XInstanceSigs Enable instance signatures. -XInterruptibleFFI Enable interruptible FFI. -XKindSignatures Enable kind signatures. Implied by TypeFamilies and PolyKinds. -XLambdaCase Enable lambda-case expressions. -XLexicalNegation Use whitespace to determine whether the minus sign stands for negation or subtraction. -XLiberalTypeSynonyms Enable liberalised type synonyms. -XLinearTypes Enable linear types. Implies MonoLocalBinds. -XListTuplePuns Enable punning for list, tuple and sum types. -XMagicHash Allow # as a postfix modifier on identifiers. -XMonadComprehensions Enable monad comprehensions. -XMonoLocalBinds Enable do not generalise local bindings. Implied by TypeFamilies and GADTs. -XMultiParamTypeClasses Enable multi parameter type classes. Implied by FunctionalDependencies. Implies ConstrainedClassMethods. -XMultiWayIf Enable multi-way if-expressions. -XNamedFieldPuns Enable record puns. -XNamedWildCards Enable named wildcards. -XNegativeLiterals Enable support for negative literals. -XNoImplicitPrelude Don't implicitly import Prelude. Implied by RebindableSyntax. -XNoMonomorphismRestriction Disable the monomorphism restriction. -XNondecreasingIndentation Allow nested contexts to be at the same indentation level as its enclosing context. -XNoPatternGuards Disable pattern guards. Implied by Haskell98. -XNoTraditionalRecordSyntax Disable support for traditional record syntax (as supported by Haskell 98) C {f = x} -XNPlusKPatterns Enable support for n+k patterns. Implied by Haskell98. -XNullaryTypeClasses Deprecated, does nothing. nullary (no parameter) type classes are now enabled using MultiParamTypeClasses. -XNumDecimals Enable support for 'fractional' integer literals. -XNumericUnderscores Enable support for numeric underscores. -XOverlappingInstances Enable overlapping instances. -XOverloadedLabels Enable overloaded labels. -XOverloadedLists Enable overloaded lists. -XOverloadedRecordDot Record '.' syntax -XOverloadedRecordUpdate Record '.' syntax record updates -XOverloadedStrings Enable overloaded string literals. -XPackageImports Enable package-qualified imports. -XParallelListComp Enable parallel list comprehensions. -XPartialTypeSignatures Enable partial type signatures. -XPatternSynonyms Enable pattern synonyms. -XPolyKinds Enable kind polymorphism. Implies KindSignatures. -XPostfixOperators Enable postfix operators. -XQualifiedDo Enable qualified do-notation desugaring. -XQuantifiedConstraints Allow forall quantifiers in constraints. -XQuasiQuotes Enable quasiquotation. -XRank2Types Enable rank-2 types. Synonym for RankNTypes. -XRankNTypes Enable rank-N types. Implied by ImpredicativeTypes. -XRebindableSyntax Employ rebindable syntax. Implies NoImplicitPrelude. -XRecordWildCards Enable record wildcards. Implies DisambiguateRecordFields. -XRecursiveDo Enable recursive do (mdo) notation. -XRequiredTypeArguments Enable required type arguments in terms. -XRoleAnnotations Enable role annotations. -XSafe Enable the Safe Haskell Safe mode. -XScopedTypeVariables Enable lexically-scoped type variables. -XStandaloneDeriving Enable standalone deriving. -XStandaloneKindSignatures Allow the use of standalone kind signatures. -XStarIsType Treat * as Data.Kind.Type. -XStaticPointers Enable static pointers. -XStrict Make bindings in the current module strict by default. -XStrictData Enable default strict datatype fields. -XTemplateHaskell Enable Template Haskell. -XTemplateHaskellQuotes Enable quotation subset of Template Haskell. -XTransformListComp Enable generalised list comprehensions. -XTrustworthy Enable the Safe Haskell Trustworthy mode. -XTupleSections Enable tuple sections. -XTypeAbstractions Enable type abstraction syntax in patterns and type variable binders. -XTypeApplications Enable type application syntax in terms and types. -XTypeData Enable type data declarations. -XTypeFamilies Enable type families. Implies ExplicitNamespaces, KindSignatures, and MonoLocalBinds. -XTypeFamilyDependencies Enable injective type families. Implies TypeFamilies. -XTypeInType Deprecated. Enable kind polymorphism and datatype promotion. -XTypeOperators Enable type operators. Implies ExplicitNamespaces. -XTypeSynonymInstances Enable type synonyms in instance heads. Implied by FlexibleInstances. -XUnboxedSums Enable unboxed sums. -XUnboxedTuples Enable the use of unboxed tuple syntax. -XUndecidableInstances Enable undecidable instances. -XUndecidableSuperClasses Allow all superclass constraints, including those that may re- sult in non-termination of the typechecker. -XUnicodeSyntax Enable unicode syntax. -XUnliftedDatatypes Enable unlifted data types. -XUnliftedFFITypes Enable unlifted FFI types -XUnliftedNewtypes Enable unlifted newtypes. -XUnsafe Enable Safe Haskell Unsafe mode. -XViewPatterns Enable view patterns. Linking options -c Stop after generating object (.o) file -debug Use the debugging runtime -dylib-install-name path Set the install name (via -install_name passed to Apple's linker), specifying the full install path of the library file. Any libraries or executables that link with it later will pick up that path as their runtime search location for it. (Dar- win/OS X only) -dynamic Build dynamically-linked object files and executables -dynload Selects one of a number of modes for finding shared libraries at runtime. -eventlog Enable runtime event tracing -fcompact-unwind Instruct the linker to produce a __compact_unwind section. -fkeep-cafs Do not garbage-collect CAFs (top-level expressions) at runtime -flink-rts Link the runtime when generating a shared or static library -fno-embed-manifest Do not embed the manifest in the executable (Windows only) -fno-gen-manifest Do not generate a manifest file (Windows only) -fno-shared-implib Don't generate an import library for a DLL (Windows only) -framework name On Darwin/OS X/iOS only, link in the framework name. This option corresponds to the -framework option for Apple's Linker. -framework-path dir On Darwin/OS X/iOS only, add dir to the list of directories searched for frameworks. This option corresponds to the -F op- tion for Apple's Linker. -fsplit-sections Split sections for link-time dead-code stripping -fuse-rpaths Set the rpath based on -L flags -fwhole-archive-hs-libs When linking a binary executable, this inserts the flag -Wl,--whole-archive before any -l flags for Haskell libraries, and -Wl,--no-whole-archive afterwards -L dir Add dir to the list of directories searched for libraries -l lib Link in library lib -main-is thing Set main module and function -no-hs-main Don't assume this program contains main -no-pie Don't instruct the linker to produce a position-independent exe- cutable. -no-rtsopts-suggestions Don't print RTS suggestions about linking with -rtsopts[=none|some|all|ignore|ignoreAll]. -package name Expose package pkg -pie Instruct the linker to produce a position-independent exe- cutable. -rdynamic This instructs the linker to add all symbols, not only used ones, to the dynamic symbol table. Currently Linux and Win- dows/MinGW32 only. This is equivalent to using -optl -rdynamic on Linux, and -optl -export-all-symbols on Windows. -rtsopts[=none|some|all|ignore|ignoreAll] Control whether the RTS behaviour can be tweaked via com- mand-line flags and the GHCRTS environment variable. Using none means no RTS flags can be given; some means only a minimum of safe options can be given (the default); all (or no argument at all) means that all RTS flags are permitted; ignore means RTS flags can be given, but are treated as regular arguments and passed to the Haskell program as arguments; ignoreAll is the same as ignore, but GHCRTS is also ignored. -rtsopts does not affect -with-rtsopts behavior; flags passed via -with-rtsopts are used regardless of -rtsopts. -shared Generate a shared library (as opposed to an executable) -single-threaded Use the single-threaded runtime -static Use static Haskell libraries -staticlib Generate a standalone static library (as opposed to an exe- cutable). This is useful when cross compiling. The library to- gether with all its dependencies ends up in in a single static library that can be linked against. -threaded Use the threaded runtime -with-rtsopts=opts Set the default RTS options to opts. Miscellaneous options -ddump-mod-cycles Dump module cycles -fdefer-out-of-scope-variables Convert variable out of scope variables errors into warnings. Implied by -fdefer-type-errors. See also -Wdeferred-out-of-scope-variables. -fdefer-type-errors Turn type errors into warnings, deferring the error until run- time. Implies -fdefer-typed-holes and -fdefer-out-of-scope-variables. See also -Wdeferred-type-errors. -fdefer-typed-holes Convert typed hole errors into warnings, deferring the error un- til runtime. Implied by -fdefer-type-errors. See also -Wtyped-holes. -fexternal-interpreter Run interpreted code in a separate process -ffamily-application-cache Use a cache when reducing type family applications -fglasgow-exts Deprecated. Enable most language extensions; see Controlling editions and extensions for exactly which ones. -fno-safe-haskell Disable Safe Haskell -ghcversion-file path to ghcversion.h (GHC as a C compiler only) Use this ghcversion.h file -H size Set the minimum size of the heap to size -hidden-module module name A module which should not be visible outside its unit. -j[n] When compiling with --make, compile n modules in parallel. -jsem When compiling with --make, coordinate with other processes through the semaphore sem to compile modules in parallel. -reexported-module module name A module which should be reexported from this unit. -this-package-name unit-id The name of the package which this module would be part of when installed. -unit @filename Specify the options to build a specific unit. -working-dir dir Specify the directory a unit is expected to be compiled in. Modes of operation --frontend module run GHC with the given frontend plugin; see Frontend plugins for details. --help Display help --info display information about the compiler --interactive Interactive mode - normally used by just running ghci; see Using GHCi for details. --make Build a multi-module Haskell program, automatically figuring out dependencies. Likely to be much easier, and faster, than using make; see Using ghc --make for details. --numeric-version display GHC version (numeric only) --print-booter-version display bootstrap compiler version --print-build-platform display platform on which GHC was built --print-c-compiler-flags C compiler flags used to build GHC --print-c-compiler-link-flags C linker flags used to build GHC --print-debug-on print whether GHC was built with -DDEBUG --print-global-package-db display GHC's global package database directory --print-have-interpreter display whether GHC was built with interactive support --print-have-native-code-generator display whether target platform has NCG support --print-host-platform display host platform of GHC --print-ld-flags display linker flags used to compile GHC --print-leading-underscore display use of leading underscores on symbol names --print-libdir display GHC library directory --print-object-splitting-supported display whether GHC supports object splitting --print-project-git-commit-id display Git commit id GHC is built from --print-project-version display GHC version --print-rts-ways display which way RTS was built --print-stage display stage number of GHC --print-support-smp display whether GHC was compiled with SMP support --print-tables-next-to-code display whether GHC was compiled with --enable-ta- bles-next-to-code --print-target-platform display target platform of GHC --print-unregisterised display whether this GHC was built in unregisterised mode --run file Run a Haskell program. --show-iface file display the contents of an interface file. --show-options display the supported command line options --supported-extensions display the supported language extensions --version display GHC version -e expr Evaluate expr; see Expression evaluation mode for details. -M generate dependency information suitable for use in a Makefile; see Dependency generation for details. -shared Create a shared object. Individual optimizations -fasm-shortcutting Enable shortcutting on assembly. Implied by -O2. -fbinary-blob-threshold=n default: 500K. Tweak assembly generator for binary blobs. -fblock-layout-cfg Use the new cfg based block layout algorithm. Implied by -O. -fblock-layout-weightless Ignore cfg weights for code layout. -fblock-layout-weights Sets edge weights used by the new code layout algorithm. -fcall-arity Enable call-arity optimisation. Implied by -O. -fcase-folding Enable constant folding in case expressions. Implied by -O. -fcase-merge Enable case-merging. Implied by -O. -fcmm-control-flow Enable control flow optimisation in the Cmm backend. Implied by -O. -fcmm-elim-common-blocks Enable Cmm common block elimination. Implied by -O. -fcmm-sink Enable Cmm sinking. Implied by -O. -fcmm-static-pred Enable static control flow prediction. Implied by -O. -fcore-constant-folding Enable constant folding in Core. Implied by -O. -fcpr-anal Turn on Constructed Product Result analysis. Implied by -O. -fcross-module-specialise Turn on specialisation of overloaded functions imported from other modules. Implied by -O. -fcse Enable common sub-expression elimination. Implied by -O. -fdicts-cheap Make dictionary-valued expressions seem cheap to the optimiser. -fdicts-strict Make dictionaries strict. Implied by -O2. -fdmd-tx-dict-sel (deprecated) Use a special demand transformer for dictionary se- lectors. -fdmd-unbox-width=n default: 3. Boxity analysis pretends that returned records with this many fields can be unboxed. -fdo-clever-arg-eta-expansion Enable sophisticated argument eta-expansion. Implied by -O. -fdo-eta-reduction Enable eta-reduction. Always enabled by default. -fdo-lambda-eta-expansion Enable lambda eta-expansion. Always enabled by default. -feager-blackholing Turn on eager blackholing -fenable-rewrite-rules Switch on all rewrite rules (including rules generated by auto- matic specialisation of overloaded functions). Implied by -O. -fexcess-precision Enable excess intermediate precision -fexitification Enables exitification optimisation. Implied by -O. -fexpose-all-unfoldings Expose all unfoldings, even for very large or recursive func- tions. -ffloat-in Turn on the float-in transformation. Implied by -O. -ffull-laziness Turn on full laziness (floating bindings outwards). Implied by -O. -ffun-to-thunk (deprecated) superseded by -ffull-laziness. -fignore-asserts Ignore assertions in the source. Implied by -O. -fignore-interface-pragmas Ignore pragmas in interface files. Implied by -O0 only. -finline-generics Annotate methods of derived Generic and Generic1 instances with INLINE[1] pragmas based on heuristics. Implied by -O. -finline-generics-aggressively Annotate methods of all derived Generic and Generic1 instances with INLINE[1] pragmas. -finter-module-far-jumps Assume code sections can be very large. -fkeep-auto-rules Keep all "auto" rules, generated by specialisation -flate-dmd-anal Run demand analysis again, at the end of the simplification pipeline -flate-specialise Run a late specialisation pass -fliberate-case Turn on the liberate-case transformation. Implied by -O2. -fliberate-case-threshold=n default: 2000. Set the size threshold for the liberate-case transformation to n -fllvm-pass-vectors-in-regs (deprecated) Does nothing -flocal-float-out Enable local floating definitions out of let-binds. -flocal-float-out-top-level Enable local floating to float top-level bindings -floopification Turn saturated self-recursive tail-calls into local jumps in the generated assembly. Implied by -O. -fmax-forced-spec-args=n default: 333. Maximum number of value arguments for forced Spec- Constr specializations. -fmax-inline-alloc-size=n default: 128. Set the maximum size of inline array allocations to n bytes (default: 128). -fmax-inline-memcpy-insns=n default: 32. Inline memcpy calls if they would generate no more than n pseudo instructions. -fmax-inline-memset-insns=n default: 32. Inline memset calls if they would generate no more than n pseudo instructions -fmax-simplifier-iterations=n default: 4. Set the max iterations for the simplifier. -fmax-uncovered-patterns=n default: 4. Set the maximum number of patterns to display in warnings about non-exhaustive ones. -fmax-worker-args=n default: 10. Maximum number of value arguments for a worker. -fno-opt-coercion Turn off the coercion optimiser -fno-pre-inlining Turn off pre-inlining -fno-state-hack Turn off the state hackwhereby any lambda with a real-world state token as argument is considered to be single-entry. Hence OK to inline things inside it. -fomit-interface-pragmas Don't generate interface pragmas. Implied by -O0 only. -fomit-yields Omit heap checks when no allocation is being performed. -foptimal-applicative-do Use a slower but better algorithm for ApplicativeDo -fpedantic-bottoms Make GHC be more precise about its treatment of bottom (but see also -fno-state-hack). In particular, GHC will not eta-expand through a case expression. -fpolymorphic-specialisation Allow specialisation to abstract over free type variables -fregs-graph Use the graph colouring register allocator for register alloca- tion in the native code generator. -fregs-iterative Use the iterative coalescing graph colouring register allocator in the native code generator. -fsimpl-tick-factor=n default: 100. Set the percentage factor for simplifier ticks. -fsimplifier-phases=n default: 2. Set the number of phases for the simplifier. Ig- nored with -O0. -fsolve-constant-dicts When solving constraints, try to eagerly solve super classes us- ing available dictionaries. Implied by -O. -fspec-constr Turn on the SpecConstr transformation. Implied by -O2. -fspec-constr-count=n default: 3.* Set to n the maximum number of specialisations that will be created for any one function by the SpecConstr transfor- mation. -fspec-constr-keen Specialize a call with an explicit constructor argument, even if the argument is not scrutinised in the body of the function -fspec-constr-threshold=n default: 2000. Set the size threshold for the SpecConstr trans- formation to n. -fspec-eval Enables speculative evaluation. -fspec-eval-dictfun Enables speculative evaluation of dictionary functions. -fspecialise Turn on specialisation of overloaded functions. Implied by -O. -fspecialise-aggressively Turn on specialisation of overloaded functions regardless of size, if unfolding is available -fspecialise-incoherents Enable specialisation on incoherent instances -fstatic-argument-transformation Turn on the static argument transformation. -fstg-cse Enable common sub-expression elimination on the STG intermediate language. Implied by -O. -fstg-lift-lams Enable late lambda lifting on the STG intermediate language. Im- plied by -O2. -fstg-lift-lams-known Allow turning known into unknown calls while performing late lambda lifting. -fstg-lift-lams-non-rec-args Create top-level non-recursive functions with at most <n> para- meters while performing late lambda lifting. -fstg-lift-lams-rec-args Create top-level recursive functions with at most <n> parameters while performing late lambda lifting. -fstrictness Turn on demand analysis. Implied by -O. Implies -fworker-wrapper -fstrictness-before=n Run an additional demand analysis before simplifier phase n -funbox-small-strict-fields Flatten strict constructor fields with a pointer-sized represen- tation. Implied by -O. -funbox-strict-fields Flatten strict constructor fields -funfolding-case-scaling=n default: 30. Apply a penalty of (inlining_cost * 1/n) for each level of case nesting. -funfolding-case-threshold=n default: 2. Reduce inlining for cases nested deeper than n. -funfolding-creation-threshold=n default: 750. Tweak unfolding settings. -funfolding-dict-discount=n default: 30. Tweak unfolding settings. -funfolding-fun-discount=n default: 60. Tweak unfolding settings. -funfolding-keeness-factor=n This has been deprecated in GHC 9.0.1. -funfolding-use-threshold=n default: 80. Tweak unfolding settings. -fworker-wrapper Enable the worker/wrapper transformation. Implied by -O and by -fstrictness. -fworker-wrapper-cbv Enable w/w splits for wrappers whos sole purpose is evaluating arguments. Optimization levels -O Enable level 1 optimisations -O0 Disable optimisations (default) -O2 Enable level 2 optimisations -On Any -On where n > 2 is the same as -O2. Package options -clear-package-db Clear the package db stack. -distrust pkg Expose package pkg and set it to be distrusted. See Safe Haskell. -distrust-all-packages Distrust all packages by default. See Safe Haskell. -fpackage-trust Enable Safe Haskell trusted package requirement for trustworthy modules. -global-package-db Add the global package db to the stack. -hide-all-packages Hide all packages by default -hide-package pkg Hide package pkg -ignore-package pkg Ignore package pkg -no-auto-link-packages Don't automatically link in the base and rts packages. -no-global-package-db Remove the global package db from the stack. -no-user-package-db Remove the user's package db from the stack. -package pkg Expose package pkg -package-db file Add file to the package db stack. -package-env file|name Use the specified package environment. -package-id unit-id Expose package by id unit-id -this-unit-id unit-id Compile to be part of unit (i.e. package) unit-id -trust pkg Expose package pkg and set it to be trusted. See Safe Haskell. -user-package-db Add the user's package db to the stack. Phases of compilation --merge-objs Merge a set of objects into a GHCi library. -C Stop after generating C (.hc file) -c Stop after generating object (.o) file -E Stop after preprocessing (.hspp file) -F Enable the use of a pre-processor (set with -pgmF cmd) -S Stop after generating assembly (.s file) -x suffix Override default behaviour for source files Overriding external programs -pgma cmd Use cmd as the assembler -pgmc cmd Use cmd as the C compiler -pgmCmmP cmd Use cmd as the C-- C pre-processor -pgmcxx cmd Use cmd as the C++ compiler -pgmF cmd Use cmd as the pre-processor (with -F only) -pgmi cmd Use cmd as the external interpreter command. -pgminstall_name_tool cmd Use cmd as the program to inject runpath into mach-o dylibs on macOS -pgmJSP cmd Use cmd as the JavaScript C pre-processor (only for javascript-backend) -pgmL cmd Use cmd as the literate pre-processor -pgml cmd Use cmd as the linker -pgmlas cmd Use cmd as the LLVM assembler -pgmlc cmd Use cmd as the LLVM compiler -pgmlm cmd Use cmd as the linker when merging object files -pgmlo cmd Use cmd as the LLVM optimiser -pgmotool cmd Use cmd as the program to inspect mach-o dylibs on macOS -pgmP cmd Use cmd as the C pre-processor (with -cpp only) -pgms cmd Use cmd as the splitter -pgmwindres cmd Use cmd as the program for embedding manifests on Windows. Phase-specific options -opta option pass option to the assembler -optc option pass option to the C compiler -optCmmP option pass option to the C-- C pre-processor. -optcxx option pass option to the C++ compiler -optF option pass option to the custom pre-processor -opti option pass option to the interpreter sub-process. -optJSP option pass option to JavaScript C pre-processor (only for javascript-backend) -optL option pass option to the literate pre-processor -optl option pass option to the linker -optlas option pass option to the LLVM assembler -optlc option pass option to the LLVM compiler -optlm option pass option to the linker when merging object files. -optlo option pass option to the LLVM optimiser -optP option pass option to cpp (with -cpp only) -optwindres option pass option to windres. -pgmc-supports-no-pie (deprecated) Indicate that the linker supports -no-pie -pgml-supports-no-pie Indicate that the linker supports -no-pie Platform-specific options -mavx (x86 only) Enable support for AVX SIMD extensions -mavx2 (x86 only) Enable support for AVX2 SIMD extensions -mavx512cd (x86 only) Enable support for AVX512-CD SIMD extensions -mavx512er (x86 only) Enable support for AVX512-ER SIMD extensions -mavx512f (x86 only) Enable support for AVX512-F SIMD extensions -mavx512pf (x86 only) Enable support for AVX512-PF SIMD extensions -mbmi (x86 only) Use BMI1 for bit manipulation operations -mbmi2 (x86 only) Use BMI2 for bit manipulation operations -mfma Use native FMA instructions for fused multiply-add float- ing-point operations -msse (x86 only) Use SSE for floating-point operations -msse2 (x86 only) Use SSE2 for floating-point operations -msse3 (x86 only) Use SSE3 for floating-point operations -msse4 (x86 only) Use SSE4 for floating-point operations -msse4.2 (x86 only) Use SSE4.2 for floating-point operations Compiler plugins -fclear-plugins Clear the list of active plugins -fplugin-library=file-path;unit-id;module;args Load a pre-compiled static plugin from an external library -fplugin-opt=module:args Give arguments to a plugin module; module must be specified with -fplugin=module -fplugin-trustworthy Trust the used plugins and no longer mark the compiled module as unsafe -fplugin=module Load a plugin exported by a given module -hide-all-plugin-packages Hide all packages for plugins by default -plugin-package pkg Expose pkg for plugins -plugin-package-id pkg-id Expose pkg-id for plugins Profiling -auto (deprecated) Alias for -fprof-auto-exported -auto-all (deprecated) Alias for -fprof-auto -caf-all (deprecated) Alias for -fprof-cafs -fno-prof-count-entries Do not collect entry counts -fprof-auto Auto-add SCC\ s to all bindings not marked INLINE -fprof-auto-calls Auto-add SCC\ s to all call sites -fprof-auto-exported Auto-add SCC\ s to all exported bindings not marked INLINE -fprof-auto-top Auto-add SCC\ s to all top-level bindings not marked INLINE -fprof-cafs Auto-add SCC\ s to all CAFs -fprof-callers=name Auto-add SCC\ s to all call-sites of the named function. -fprof-late Auto-add SCC\ s to all top level bindings after the core pipeline has run. -fprof-late-inline Auto-add SCC\ s to all top level bindings after the optimizer has run and retain them when inlining. -fprof-late-overloaded Auto-add SCC\ s to all top level overloaded bindings after the core pipeline has run. -fprof-late-overloaded-calls Auto-add SCC\ s to all call sites that include dictionary argu- ments after the core pipeline has run. -fprof-manual Process manual SCC annotations. -no-auto (deprecated) Alias for -fno-prof-auto -no-auto-all (deprecated) Alias for -fno-prof-auto -no-caf-all (deprecated) Alias for -fno-prof-cafs -prof Turn on profiling -ticky Turn on ticky-ticky profiling -ticky-allocd Track the number of times each closure type is allocated. -ticky-ap-thunk Don't use standard AP thunks on order to get more reliable entry counters. -ticky-dyn-thunk Track allocations of dynamic thunks -ticky-LNE Treat join point binders similar to thunks/functions. -ticky-tag-checks Emit dummy ticky counters to record how many tag-inference checks tag inference avoided. Program coverage -fhpc Turn on Haskell program coverage instrumentation -hpcdirdir Set the directory where GHC places .mix files. Recompilation checking -exclude-module=file Regard file as "stable"; i.e., exclude it from having dependen- cies on it. -fforce-recomp Turn off recompilation checking. This is implied by any -ddump-X option when compiling a single file (i.e. when using -c). -fignore-hpc-changes Do not recompile modules just to match changes to HPC flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi. -fignore-optim-changes Do not recompile modules just to match changes to optimisation flags. This is especially useful for avoiding recompilation when using GHCi, and is enabled by default for GHCi. -include-cpp-deps Include preprocessor dependencies -include-pkg-deps Regard modules imported from packages as unstable Redirecting output -dep-makefile file Use file as the makefile -dep-suffix suffix Make dependencies that declare that files with suffix .sufosuf depend on interface files with suffix .sufhi -dumpdir dir redirect dump files -dynhisuf suffix set the suffix to use for dynamic interface files -dyno file set dynamic output filename -dynohi file set the filename in which to put the dynamic interface -dynosuf suffix set the dynamic output file suffix -hcsuf suffix set the suffix to use for intermediate C files -hidir dir set directory for interface files -hiedir dir set directory for extended interface files -hiesuf suffix set the suffix to use for extended interface files -hisuf suffix set the suffix to use for interface files -o file set output filename -odir dir set directory for object files -ohi file set the filename in which to put the interface -osuf suffix set the output file suffix -outputdir dir set output directory -stubdir dir redirect FFI stub files Temporary files -tmpdir dir set the directory for temporary files Verbosity options -fabstract-refinement-hole-fits default: off. Toggles whether refinements where one or more of the holes are abstract are reported. -fdefer-diagnostics Defer and group diagnostic messages by severity -fdiagnostics-as-json Output diagnostics in Json format specified by JSON schema -fdiagnostics-color=always|auto|never Use colors in error messages -fdiagnostics-show-caret Whether to show snippets of original source code -ferror-spans Output full span in error messages -fhide-source-paths hide module source and object paths -fkeep-going Continue compilation as far as possible on errors -fmax-refinement-hole-fits=n default: 6. Set the maximum number of refinement hole fits for typed holes to display in type error messages. -fmax-relevant-binds=n default: 6. Set the maximum number of bindings to display in type error messages. -fmax-valid-hole-fits=n default: 6. Set the maximum number of valid hole fits for typed holes to display in type error messages. -fno-show-valid-hole-fits Disables showing a list of valid hole fits for typed holes in type error messages. -fno-sort-valid-hole-fits Disables the sorting of the list of valid hole fits for typed holes in type error messages. -fprint-axiom-incomps Display equation incompatibilities in closed type families -fprint-equality-relations Distinguish between equality relations when printing -fprint-error-index-links=always|auto|never Whether to emit diagnostic codes as ANSI hyperlinks to the Haskell Error Index. -fprint-expanded-synonyms In type errors, also print type-synonym-expanded types. -fprint-explicit-coercions Print coercions in types -fprint-explicit-foralls Print explicit forall quantification in types. See also ExplicitForAll -fprint-explicit-kinds Print explicit kind foralls and kind arguments in types. See also KindSignatures -fprint-explicit-runtime-reps Print RuntimeRep and Levity variables in types which are run- time-representation polymorphic. -fprint-potential-instances display all available instances in type error messages -fprint-redundant-promotion-ticks Print redundant DataKinds promotion ticks -fprint-typechecker-elaboration Print extra information from typechecker. -fprint-unicode-syntax Use unicode syntax when printing expressions, types and kinds. See also UnicodeSyntax -frefinement-level-hole-fits=n default: off. Sets the level of refinement of the refinement hole fits, where level n means that hole fits of up to n holes will be considered. -freverse-errors Output errors in reverse order -fshow-docs-of-hole-fits Toggles whether to show the documentation of the valid hole fits in the output. -fshow-error-context Whether to show textual information about error context -fshow-hole-constraints Show constraints when reporting typed holes. -fshow-hole-matches-of-hole-fits Toggles whether to show the type of the additional holes in re- finement hole fits. -fshow-provenance-of-hole-fits Toggles whether to show the provenance of the valid hole fits in the output. -fshow-type-app-of-hole-fits Toggles whether to show the type application of the valid hole fits in the output. -fshow-type-app-vars-of-hole-fits Toggles whether to show what type each quantified variable takes in a valid hole fit. -fshow-type-of-hole-fits Toggles whether to show the type of the valid hole fits in the output. -fsort-by-size-hole-fits Sort valid hole fits by size. -fsort-by-subsumption-hole-fits Sort valid hole fits by subsumption. -funclutter-valid-hole-fits Unclutter the list of valid hole fits by not showing provenance nor type applications of suggestions. -Rghc-timing Summarise timing stats for GHC (same as +RTS -tstderr). -v verbose mode (equivalent to -v3) -vn set verbosity level Warnings -fenable-th-splice-warnings Generate warnings for Template Haskell splices -fhelpful-errors Make suggestions for mis-spelled names. -fmax-pmcheck-models=n soft limit on the number of parallel models the pattern match checker should check a pattern match clause against -fshow-warning-groups show which group an emitted warning belongs to. -fvia-C use the C code generator -W enable normal warnings -w disable all warnings -Wall enable almost all warnings (details in Warnings and san- ity-checking) -Wall-missed-specialisations warn when specialisation of any overloaded function fails. -Wall-missed-specializations alias for -Wall-missed-specialisations -Wambiguous-fields warn about ambiguous field selectors or updates -Wauto-orphans (deprecated) Does nothing -Wbadly-staged-types warn when type binding is used at the wrong TH stage. -Wcompat enable future compatibility warnings (details in Warnings and sanity-checking) -Wcompat-unqualified-imports Report unqualified imports of core libraries which are expected to cause compatibility problems in future releases. -Wcpp-undef warn on uses of the #if directive on undefined identifiers -Wdata-kinds-tc warn when an illegal use of a type or kind without DataKinds is caught by the typechecker -Wdefault enable default flags -Wdefaulted-exception-context warn when an Control.Exception.Context.ExceptionContext implicit parameter is defaulted to Control.Exception.Context.emptyExceptionContext. -Wdeferred-out-of-scope-variables Report warnings when variable out-of-scope errors are deferred until runtime. See -fdefer-out-of-scope-variables. -Wdeferred-type-errors Report warnings when deferred type errors are enabled. This op- tion is enabled by default. See -fdefer-type-errors. -Wdeprecated-flags warn about uses of commandline flags that are deprecated -Wdeprecated-type-abstractions warn when type abstractions in constructor patterns are used without enabling TypeApplications -Wdeprecations warn about uses of functions & types that have DEPRECATED prag- mas, or WARNING pragmas with the deprecated category. -Wderiving-defaults warn about default deriving when using both DeriveAnyClass and GeneralizedNewtypeDeriving -Wderiving-typeable warn when Typeable is derived -Wdodgy-exports warn about dodgy exports -Wdodgy-foreign-imports warn about dodgy foreign imports -Wdodgy-imports warn about dodgy imports -Wduplicate-constraints warn when a constraint appears duplicated in a type signature -Wduplicate-exports warn when an entity is exported multiple times -Wempty-enumerations warn about enumerations that are empty -Werror make warnings fatal -Weverything enable all warnings supported by GHC -Wextended-warnings warn about uses of functions & types that have WARNING or DEPRE- CATED pragmas, across all categories -Wextra alias for -W -Wforall-identifier (deprecated) Does nothing -Wgadt-mono-local-binds warn when pattern matching on a GADT without MonoLocalBinds -Whi-shadowing (deprecated) warn when a .hi file in the current directory shad- ows a library -Widentities warn about uses of Prelude numeric conversions that are probably the identity (and hence could be omitted) -Wimplicit-kind-vars (deprecated) warn when kind variables are implicitly quantified over. -Wimplicit-lift warn about implicit lift in Template Haskell quotes -Wimplicit-prelude warn when the Prelude is implicitly imported -Wimplicit-rhs-quantification warn when type variables on the RHS of a type synonym are im- plicitly quantified -Winaccessible-code warn about inaccessible code -Wincomplete-export-warnings warn when some but not all of exports for a name are warned about -Wincomplete-patterns warn when a pattern match could fail -Wincomplete-record-selectors warn when a record selector application could fail -Wincomplete-record-updates warn when a record update could fail -Wincomplete-uni-patterns warn when a pattern match in a lambda expression, pattern bind- ing or a lazy pattern could fail -Winconsistent-flags warn when command line options are inconsistent in some way. -Winferred-safe-imports warn when an explicitly Safe Haskell module imports a Safe-In- ferred one -Winline-rule-shadowing Warn if a rewrite RULE might fail to fire because the function might be inlined before the rule has a chance to fire. See How rules interact with INLINE/NOINLINE pragmas. -Winvalid-haddock warn when a Haddock comment occurs in an invalid position -Wloopy-superclass-solve (deprecated) warn when creating potentially-loopy superclass constraint evidence -Wmisplaced-pragmas warn about uses of file header pragmas in the module body -Wmissed-extra-shared-lib Warn when GHCi can't load a shared lib. -Wmissed-specialisations warn when specialisation of an imported, overloaded function fails. -Wmissed-specializations alias for -Wmissed-specialisations -Wmissing-deriving-strategies warn when a deriving clause is missing a deriving strategy -Wmissing-export-lists warn when a module declaration does not explicitly list all ex- ports -Wmissing-exported-pattern-synonym-signatures warn about pattern synonyms without signatures, only if they are exported -Wmissing-exported-signatures warn about top-level functions without signatures, only if they are exported -Wmissing-exported-sigs (deprecated) warn about top-level functions without signatures, only if they are exported. takes precedence over -Wmissing-sig- natures -Wmissing-fields warn when fields of a record are uninitialised -Wmissing-home-modules warn when encountering a home module imported, but not listed on the command line. Useful for cabal to ensure GHC won't pick up modules, not listed neither in exposed-modules, nor in other-modules. -Wmissing-import-lists warn when an import declaration does not explicitly list all the names brought into scope -Wmissing-kind-signatures warn when type declarations don't have kind signatures nor CUSKs -Wmissing-local-signatures warn about polymorphic local bindings without signatures -Wmissing-local-sigs (deprecated) warn about polymorphic local bindings without sig- natures -Wmissing-methods warn when class methods are undefined -Wmissing-monadfail-instances (deprecated) Warn when a failable pattern is used in a do-block that does not have a MonadFail instance. -Wmissing-pattern-synonym-signatures warn when pattern synonyms do not have type signatures -Wmissing-poly-kind-signatures warn when inferred polykinded type or class declaration don't have kind signatures nor CUSKs -Wmissing-role-annotations warn when type declarations don't have role annotations -Wmissing-safe-haskell-mode warn when the Safe Haskell mode is not explicitly specified. -Wmissing-signatures warn about top-level functions without signatures -Wmissing-space-after-bang (deprecated) Does nothing -Wmonomorphism-restriction warn when the Monomorphism Restriction is applied -Wname-shadowing warn when names are shadowed -Wnoncanonical-monad-instances warn when Applicative or Monad instances have noncanonical defi- nitions of return, pure, (>>), or (*>). See flag description in Warnings and sanity-checking for more details. -Wnoncanonical-monadfail-instances (deprecated) warn when Monad or MonadFail instances have non- canonical definitions of fail. -Wnoncanonical-monoid-instances warn when Semigroup or Monoid instances have noncanonical defin- itions of (<>) or mappend. See flag description in Warnings and sanity-checking for more details. -Wnot (deprecated) Alias for -w -Woperator-whitespace warn on prefix, suffix, and tight infix uses of infix operators -Woperator-whitespace-ext-conflict warn on uses of infix operators that would be parsed differently were a particular GHC extension enabled -Worphans warn when the module contains orphan instance declarations or rewrite rules -Woverflowed-literals warn about literals that will overflow their type -Woverlapping-patterns warn about overlapping patterns -Wpartial-fields warn when defining a partial record field. -Wpartial-type-signatures warn about holes in partial type signatures when PartialTypeSignatures is enabled. Not applicable when PartialTypeSignatures is not enabled, in which case errors are generated for such holes. -Wprepositive-qualified-module Report imports with a leading/prepositive "qualified" -Wredundant-bang-patterns Warn about redundant bang patterns. -Wredundant-constraints Have the compiler warn about redundant constraints in type sig- natures. -Wredundant-record-wildcards Warn about record wildcard matches when the wildcard binds no patterns. -Wredundant-strictness-flags Warn about redundant strictness flags. -Wsafe warn if the module being compiled is regarded to be safe. -Wsemigroup (deprecated) Warn when a Monoid is not Semigroup, and on non-Semigroup definitions of (<>) -Wsimplifiable-class-constraints Warn about class constraints in a type signature that can be simplified using a top-level instance declaration. -Wstar-binder warn about binding the (*) type operator despite StarIsType -Wstar-is-type warn when * is used to mean Data.Kind.Type -Wtabs warn if there are tabs in the source file -Wterm-variable-capture warn when an implicitly quantified type variable captures a term's name -Wtrustworthy-safe warn if the module being compiled is marked as Trustworthy but it could instead be marked as Safe, a more informative bound. -Wtype-defaults warn when defaulting happens -Wtype-equality-out-of-scope warn when type equality a ~ b is used despite being out of scope -Wtype-equality-requires-operators warn when type equality a ~ b is used despite being out of scope -Wtyped-holes Report warnings when typed hole errors are deferred until run- time. See -fdefer-typed-holes. -Wunbanged-strict-patterns warn on pattern bind of unlifted variable that is neither bare nor banged -Wunicode-bidirectional-format-characters warn about the usage of unicode bidirectional layout override characters -Wunrecognised-pragmas warn about uses of pragmas that GHC doesn't recognise -Wunrecognised-warning-flags throw a warning when an unrecognised -W... flag is encountered on the command line. -Wunsafe warn if the module being compiled is regarded to be unsafe. See Safe Haskell -Wunsupported-calling-conventions warn about use of an unsupported calling convention -Wunsupported-llvm-version Warn when using -fllvm with an unsupported version of LLVM. -Wunticked-promoted-constructors warn if promoted constructors are not ticked -Wunused-binds warn about bindings that are unused. Alias for -Wunused-top-binds, -Wunused-local-binds and -Wunused-pattern-binds -Wunused-do-bind warn about do bindings that appear to throw away values of types other than () -Wunused-foralls warn about type variables in user-written forall\s that are un- used -Wunused-imports warn about unnecessary imports -Wunused-local-binds warn about local bindings that are unused -Wunused-matches warn about variables in patterns that aren't used -Wunused-packages warn when package is requested on command line, but not needed. -Wunused-pattern-binds warn about pattern match bindings that are unused -Wunused-record-wildcards Warn about record wildcard matches when none of the bound vari- ables are used. -Wunused-top-binds warn about top-level bindings that are unused -Wunused-type-patterns warn about unused type variables which arise from patterns in in type family and data family instances -Wwarn make warnings non-fatal -Wwarnings-deprecations warn about uses of functions & types that have DEPRECATED prag- mas, or WARNING pragmas with the deprecated category. Alias for -Wdeprecations. -Wwrong-do-bind warn about do bindings that appear to throw away monadic values that you should have bound instead -Wx-category warn about uses of functions & types that have WARNING pragmas with the given category COPYRIGHT Copyright 2015. The University Court of the University of Glasgow. All rights reserved. SEE ALSO https://www.haskell.org/ghc the GHC homepage AUTHOR The GHC Team COPYRIGHT 2023, GHC Team 9.10.3 Feb 26, 2026 GHC(1)
NAME | SYNOPSIS | DESCRIPTION | OPTIONS | COPYRIGHT | SEE ALSO | AUTHOR | COPYRIGHT
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