[mercury-users] using mercury for parsing/scanning
Fergus Henderson
fjh at cs.mu.OZ.AU
Mon Dec 31 14:54:51 AEDT 2001
On 31-Dec-2001, Dave Slutzkin <dave_slutzkin at yahoo.com> wrote:
> --- Fergus Henderson <fjh at cs.mu.OZ.AU> wrote:
> > On 31-Dec-2001, Dave Slutzkin
> > <dave_slutzkin at yahoo.com> wrote:
> > > When using DCGs to scan character strings, is
> there an
> > > alternative to this:
> > >
> > > keyword -->
> > > ['K','E','Y','W','O','R','D']
> >
> > You can use
> >
> > keyword --> string("KEYWORD").
> >
> > where string//1 can be defined as
>
> <snipped code>
>
> But surely this is inefficient? Doing the conversino
> every time the predicate is called?
With the current Mercury implementation, yes, that will probably be
inefficient.
> Another question:
>
> How do I write a char literal? '@' works fine, but
> '.' or ',' gives me problems (they look like operators
> to the compiler).
Put them in parentheses, e.g.
DotChar = ('.'),
CommaChar = (','),
...
--
Fergus Henderson <fjh at cs.mu.oz.au> | "I have always known that the pursuit
The University of Melbourne | of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh> | -- the last words of T. S. Garp.
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