[Haskell-cafe] Re: catching fails on read

[Jacques Bergeron]

Don Stewart <dons <at> galois.com> writes:

> 
> jbergeron:
> > I'm new to Haskell and have a stupid question.
> > 
> > How can a catch a parsing error on a read? Something like 
> > 
> > let s = "e"
> > in read s :: Int
> > 
> > I've been searching for a trick and couldn't find one. I want to enter 
> > commands directly from the keyboard and don't want the program to abort if 
I 
> > do a typing error.
> 
>       maybeRead :: Read a => String -> Maybe a
>       maybeRead s = case reads s of
>           [(x, rest)] | all isSpace rest -> Just x
>           _         -> Nothing
> 
> There's an open ticket to add this to the base library.
> 


So reads (or readsPrec) is the "parser" equivalent to read. Should have 
catched that, sorry.

Thanks for your time.

Jacques