EEP: XXX
Title: F/N converts to {F,N} in *all* directives
Version: $Revision: 14 $
Last-Modified: $Date: 2007-06-29 16:24:01 +0200 (Fri, 29 Jun 2007) $
Author: Richard A. O'Keefe <ok@cs.otago.ac.nz>
Status: Draft
Type: Standards Track
Erlang-Version: R12B-4
Content-Type: text/plain
Created: 22-Sep-2008
Post-History:



Abstract

    In directives the form F/N (where F is an atom and N
    is a non-negative integer) should be converted to {F,N}.



Specification

    In any directive the form F/N (where F is an atom and N
    is a non-negative integer) should be converted to {F,N},
    provided that it is not in an expression that would be
    evaluated.

    Other occurrences of X/Y are not addressed by this EEP.
    In particular, occurrences of X/Y in -record or -enum
    declarations would be evaluated, so are not affected.


Motivation

    Compare

      -compile({inline,
          [{ukeymerge3_12,13}, {ukeymerge3_21,13},
           {rukeymerge3_12a,11}, {rukeymerge3_21a,13},
           {rukeymerge3_12b,12}, {rukeymerge3_21b,12}]}).

      -deprecated(
          [{new_set,0},{set_to_list,1},{list_to_set,1},{subset,2}]).

    with

      -compile({inline, [
	  ukeymerge3_12/13, rukeymerge3_12a/11, rukeymerge3_12b/12,
	  ukeymerge3_21/13, rukeymerge3_21a/13, rukeymerge3_21b/12]}).

      -deprecated([
          list_to_set/1, new_set/0, set_to_list/1, subset/2]).

    The improvement in readability is dramatic.

    The improvement in consistency is worth having:  it's no longer
    a case of new_set/0 in an -export or -import directive but
    {new_set,0} in a -deprecated directive, it's the same in all
    directives, making it easier to find directives that mention a
    particular function.



Rationale

    Directives that contain real expressions, such as -record (and,
    if it is accepted, -enum) require a certain amount of care.
    Otherwise, F/N occurrences in -export and -import directives
    _are_ converted to tuples (by farity_list), so this is just a
    small matter of extending the notion elsewhere.  I cannot
    imagine why this wasn't done years ago.



Backwards Compatibility

    There are currently no directives where F/N is accepted,
    is not part of an expression to be evaluated, and does
    not signify a function, and those where it does signify
    a function already treat it as an {F,N} tuple.

    No existing code can be affected.



Reference Implementation

    None yet; I really ought to be writing exam questions.



References
    
    None.



Copyright

    This document has been placed in the public domain.



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