[erlang-bugs] compile and syntax_tools disagree

Bjorn Gustavsson <>
Tue Apr 3 14:41:06 CEST 2007


We'll clarify the documentation in R11B-5.

/Björn

"Ulf Wiger \(TN/EAB\)" <> writes:

> I didn't miss out on it. I was trying to 
> keep the email short. (:
> 
> The way I read the documentation in it's current
> state is that it is supposed to work as syntax_tools  
> does, where
> 
> [G1, G2, ...] is a conjunction of guards, and 
> [[G11,G12,...],[G21,G22,...],...] is a disjunction.
> 
> I have no problem with the compiler requiring 
> [[G]] rather than [G]. I have changed the output
> of my code generator to this, since clearly - 
> bug or no bug - this would have been a correct
> pattern.
> 
> If Rep(Gss) had been used, as you suggest, it 
> would indeed have been more obvious, and also 
> correctly described the current behaviour of
> the compiler.  ,-)
> 
> BR,
> Ulf W
> 
> > -----Original Message-----
> > From: Richard Carlsson [mailto:] 
> > Sent: den 3 april 2007 13:01
> > To: Ulf Wiger (TN/EAB)
> > Cc: Bjorn Gustavsson; 
> > Subject: Re: [erlang-bugs] compile and syntax_tools disagree
> > 
> > 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.htm
> > > l
> > > 
> > > "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
> > 
> > 
> 

-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB




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