Erlang language issues

Bengt Kleberg <>
Wed Apr 17 13:57:16 CEST 2002


> Date: Tue, 16 Apr 2002 00:37:29 -0500
> From: Chris Pressey <>


> With any production language, retaining backwards-compatibility is
> important, some might even say crucial.

perhaps we should at this point seperate
1 binary backwards-compatibility
2 source backwards-compatibility

i think case 2 could still allow evolution. compiler for release X has
a feature. compiler X+1 warns about this features soon to be demise,
and suggest a replacement. compiler X+2 stops with error.

case 1 does not allow such an evolution. but sometimes (yap => beam)
there is a clean break, and one is allowed to evolve things by case 2.


...deleted

> But, Erlang treats this almost as a syntactic rule, rather than a semantic
> one - the syntax of a guard expression disallows side-effects.  This seems
> a bit strict - very understandable, considering the origins of the
> language, but a bit strict nonetheless.  Reformulating it as a semantic
> rule would be a bit nicer, in my mind.

showing my ignorance i must at this point ask if there is a (simple)
explanation for syntax vs semantics.


bengt




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