Re: Literal quote character causes exception.

[Daniel Diaz]

Nicolas,

after looking carefully at the ISO standard, there is no bug here. ISO 
says the syntax is:

0'<single quoted char>

where <single quoted char> is a character that could appear in a quoted 
string. So if you want to use ' inside either you have to write it twice 
('') or to escape it \'

You should use one of the valid forms: 0''' or 0'\'

I agree the result is not very nice...
In 1.3.2 I will relax the lexer to also accept 0'' (to remain compatible 
with other Prolog systems).

Daniel

Daniel Diaz wrote:
> Thanks for this bug report.
>
> Will be fixed
>
> Daniel
>
> Nicolas Pelletier wrote:
> > Hello,
> >
> > I found the following behaviour both in GNU Prolog 1.3.1 and GNU
> > Prolog 20090310, which I believe is incorrect:
> >
> > address@hidden:~/tmp$ gprolog
> > GNU Prolog 1.3.2
> > By Daniel Diaz
> > Copyright (C) 1999-2009 Daniel Diaz
> > | ?- X = 0''.
> > uncaught exception: error(syntax_error('user_input:1 (char:8) quote
> > character expected here'),read_term/3)
> >
> > I expected the substitution X = 39 as the result of my query. Would
> > you please look into this problem ?
> >
> > Thanks in advance.
> >
> >   


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