[Haskell-beginners] Functional Parses

Robert Heumüller mailing at heum.de
Tue Jul 3 23:02:21 CEST 2012


Thank you very much. 

I'll check out the code on the website tomorrow and hopefully this will
solve the problem. 

Whenever monads apper things seem to get tricky - sadly there won't be
a lecture on functional programming in the next semester at the
university I study at :(


Am Tue, 3 Jul 2012 18:01:32 +0100
schrieb Stephen Tetley <stephen.tetley at gmail.com>:

> On 3 July 2012 15:13, Christian Maeder <Christian.Maeder at dfki.de>
> wrote:
> 
> > This type synonym is unsuitable for a Monad instance.
> > Better would be:
> >   newtype Parser a = Parser (String -> [(a, String)])
> > but that would require to change your code below.
> 
> This is alluded to in the closing chapter remarks (section 8.9) of
> Graham Hutton's book and there is code available on the website that
> accompanies the book that "solves" the problem. Unfortunately, this
> chapter does seem to trip people up who use the book for self study.
> 
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