[erlang-bugs] parser/preprocessor bug

[Robert Virding]

Originally the parentheses were mandatory but then the need for them around an record expression was removed to "improve" the syntax. Only in some cases though. Sorry for griping but I think it was a bad change. Other people have had exactly the same errors.

Robert

----- Original Message -----
> On Fri, Nov 18, 2011 at 03:46:16PM +0100, Joe Armstrong wrote:
> > On Fri, Nov 18, 2011 at 2:16 PM, Vlad Dumitrescu
> > <vladdu55@REDACTED> wrote:
> > 
> > > Hi,
> > >
> > > On Fri, Nov 18, 2011 at 14:11, Joe Armstrong <erlang@REDACTED>
> > > wrote:
> > > > -module(bug).
> > > > -compile(export_all).
> > > > -record(bug,{a}).
> > > > test() ->
> > > >     [#bug{a=1} #bug{a=2}].
> > >
> > > It's not a bug, it's the same as
> > >
> > > test() ->
> > >    B = #bug{a=1},
> > >     [B#bug{a=2}].
> > >
> > >
> > Ouch - oh dear you're right.
> > 
> > When I wrote this I thought #bug{a=1} is syntactic sugar for
> > {bug,1}
> > therefore [#bug{a=1} #bug{a=2}] is the same as [{bug1,} {bug,2}]
> > which is
> > an invalid list.
> 
> I have not tried but you can think of it like that:
>   [#bug{a=1} #bug{a=2}]
> is
>   [{bug,1} #bug{a=2}] %% uncertain if valid
> is
>   [setelement(2, {bug,1}, 2)]
> 
> since R#bug{a=A} is syntactical sugar for (kind of)
>   if is_record(R, bug) -> setelement(2, R, A) end
> in the context of your record definition.
> 
> > 
> > /J
> > 
> > 
> > 
> > 
> > 
> > > regards,
> > > Vlad
> > >
> 
> > _______________________________________________
> > erlang-bugs mailing list
> > erlang-bugs@REDACTED
> > http://erlang.org/mailman/listinfo/erlang-bugs
> 
> 
> --
> 
> / Raimo Niskanen, Erlang/OTP, Ericsson AB
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