Proposal: Add Text.Read.maybeRead :: Read a => String -> Maybe a
lennart at augustsson.net
Sun Feb 10 18:33:16 EST 2008
Because the fail method is an abomination that should never have been
included in the Monad class.
2008/2/7 Jeff Polakow <jeff.polakow at db.com>:
> Why not allow an arbitrary monad?
> readM :: (Monad m, Read a) => String -> String -> m a
> readM errMsg s = case reads s of
> [(x, "")] -> return x
> _ -> fail errMsg
> libraries-bounces at haskell.org wrote on 02/07/2008 01:46:48 PM:
> > This function is typically defined once per project. So its
> > about time this safe variant of 'read' made it into the base.
> > maybeRead :: Read a => String -> Maybe a
> > maybeRead s = case reads s of
> > [(x, "")] -> Just x
> > _ -> Nothing
> > Consideration period: 1 week.
> > Patch to Text.Read attached.
> > [attachment "maybeRead.patch" deleted by Jeff Polakow/db/dbcom]
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