Abstract Form

Arndt Jonasson <>
Thu Jul 6 09:27:47 CEST 2000


In article <>,
Vance Shipley <> wrote:
>
>I've been looking at the stdlib modules which parse
>Erlang.  There are a few which return {ok, AbsForm}.
>I can't find a definition for this anywhere.  The
>manual page for erl_parse says:
>
>parse_form(Tokens) -> {ok, AbsForm} | {error, ErrorInfo}
>...
>	AbsForm = term()
>...	
>	See section Abstract Form below for a description 
>	of AbsForm. 
>
>Unfortunately the section "Abstract Form" at the bottom 
>of this page says:
>
>	To be supplied

There is still no official documentation of the Erlang abstract
format. It is described in an appendix to the "Erlang Reference
Manual" by Jonas Barklund, which hasn't been made available to
users yet - as far as I know, there is no reason why it couldn't,
except that it needs to be updated with the latest language changes.

For the moment, the module 'erl_id_trans' in the 'stdlib' application
provides a kind of definition (without the semantics). It traverses
every kind of Erlang abstract structure, and does nothing with it
(it's an identity parse transform).

The source code for the parser, "erl_parse.yrl", may also be sufficiently
readable to serve as a definition.
-- 
Arndt Jonasson              Ericsson Utvecklings AB
      ÄT2/UAB/F/P
+46 8 719 75 87             126 25 Stockholm



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