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lfe_macro(3)							  lfe_macro(3)

NAME
       lfe_macro - Lisp	Flavoured Erlang (LFE) macro expander

SYNOPSIS
       This  module  provides an interface to the LFE macro expander.  The ex-
       pander is used by the LFE compile and in	the shell but can also be used
       by applications explicitly wanting to handle a file.

DATA TYPES
       sexpr()

       An LFE s-expression, a list structure.

       filesexpr() = {Sexpr,Line}

       This is the format returned by lfe_io:parse_file/1 and is used  by  the
       compiler	to give	better error information.

       env()

       This   is   an	macro	and   evaluation  environment  as  created  by
       lfe_lib:new_env().

       mac_state()

       This is the internal state used by the macro expander.

EXPORTS
       expand_expr(Sexpr, Env) -> {yes,Exp} | no.

       expand_expr_1(Sexpr, Env) -> {yes,Exp} |	no.

       where

	      Sexpr = Exp = sexpr()
	      Env = env()

       Test if the top s-expression here is a macro call, if so	expand it  and
       return  {yes,Expansion},	if not then return no.	expand_expr/2 will ex-
       pand the	top s-expression as much  as  possible	while  expand_expr_1/2
       will  only  try	it once.  These	functions use the macro	definitions in
       the environment and the standard	pre-defined macros.

       expand_expr_all(Sexpr, Env) -> Sexpr.

       where

	      Sexpr = sexpr()
	      Env = env()

       Expand all macros in Sexpr either using the definitions in Env or  just
       the  default macros.  Note that any eventual new	macro definitions will
       be lost.

       expand_form_init(Deep, Keep) -> MacState

       where

		Deep = boolean()
		Keep = boolean()
		MacState = mac_state()

       Create an internal macro	state.	Deep determines	whether	the form is to
       be expanded internally at depth and Keep	whether	macro definition forms
       are to be kept.

       expand_fileforms([FileForm], Env, Deep, Keep) ->	ExpRet

       expand_fileforms([FileForm], Env, MacState) -> ExpRet

       where

		FileForm = filesexpr()
		Env = env()
		Deep = boolean()
		Keep = boolean()
		MacState = mac_state()
		ExpRet = {yes,[FileSexpr],Env,Warnings}	|
			 {error,Errors,Warnings}

       expand a	sequence of file forms.

       expand_form(Form, Line, Env, MacState) -> RetState

       expand_fileform(FileForm, Env, MacState)	-> RetState

       where

		Form = sexpr()
		FileForm = filesexpr()
		Line = integer()
		Env = env()
		MacState = mac_state()
		RetState = {ok,Form,Env,Macstate} |
			   {error,Errors,Warnings,MacState}

       Expand a	file form using	the environment	and macro state.

SEE ALSO
       lfe_comp(3), lfe_gen(3)

AUTHORS
       Robert Virding.

				   2008-2020			  lfe_macro(3)

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