[Haskell-cafe] handling read exceptions
S. Alexander Jacobson
alex at alexjacobson.com
Mon Apr 12 13:58:01 EDT 2004
My point is that I am reading in name/value pairs
and once I know the name, I know the type of the
value, but I don't want to have to pass that
information programatically to the point in the
code where I am doing the read.
On Mon, 12 Apr 2004, Sven Panne wrote:
> S. Alexander Jacobson wrote:
> > I want to read strings that look like "2" or
> > "hello" into values of type Integer or String.
> > The problem is that read requires that strings be
> > read as "\"hello\"". Is there a way either to
> > convince read to not require wrapping quotation
> > marks or, alternetively, to catch a read
> > exception, and do something sane?
> "reads" is probably what you are looking for:
> Prelude> (reads :: ReadS Integer) ""
> Prelude> (reads :: ReadS Integer) "a"
> Prelude> (reads :: ReadS Integer) "2"
> Prelude> (reads :: ReadS Integer) "123blah"
> And reading a string the way you want is best done by "id". :-)
S. Alexander Jacobson mailto:me at alexjacobson.com
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