[erlang-bugs] compile and syntax_tools disagree

Richard Carlsson <>
Tue Apr 3 13:00:37 CEST 2007


Ulf Wiger (TN/EAB) wrote:
> Maybe it's just I who don't understand how to read the 
> doc on abstract forms, but quoted from
> http://www.erlang.org/doc/doc-5.5.4/erts-5.5.4/doc/html/part_frame.html
> 
> "If C is a function clause ( Ps ) when Gs -> B where Ps 
> is a pattern sequence, Gs is a guard sequence and B 
> is a body, then 
> Rep(C) = {clause,LINE,Rep(Ps),Rep(Gs),Rep(B)}. 
> ...
> A guard Gs is a nonempty sequence of guard tests G_1, ..., 
> G_k, and Rep(Gs) = [Rep(G_1), ..., Rep(G_k)]. 

Don't miss the immediately following paragraph:

"A guard sequence Gss is a sequence of guards Gs_1; ...; Gs_k, and 
Rep(Gss) = [Rep(Gs_1), ..., Rep(Gs_k)]. If the guard sequence is empty, 
Rep(Gss) = []."

The description of {clause, ...} that you quote above says "Gs is a 
guard sequence". It would have been more obvious if that paragraph had 
used Gss instead of Gs.

     /Richard




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