But here we need to get the grammar from users. How can I do that? Or how can input the grammar in my code??
Sent from my iPhone On Jul 22, 2011, at 5:04 AM, Yves Parès <[email protected]> wrote: > You can do that using the Typeable class and possibly the Dynamic type. > (Data.Typeable and Data.Dynamic in base) > > When you have: > > foo :: (Typeable a, Num a) => a -> a > foo x = case (cast x :: Maybe Int) of > Just x' -> x + 12 > _ -> x > > foo will accept every instance of Num but will add 12 to it only if it is an > Int. > > Dynamic wraps an instance of Typeable. > > 2011/7/22 Patrick Browne <[email protected]> > Is it possible to access type information and perform either of the > following in a Haskell program? > > 1) Find the type/class of a variable > e.g. a type predicate: is y of-type A, or is y of-Class A > > 2) Assert the type of a variable > e.g. if y.length > 100 then y is of type big. > > Regards, > Pat > > > This message has been scanned for content and viruses by the DIT Information > Services E-Mail Scanning Service, and is believed to be clean. > http://www.dit.ie > > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe > > _______________________________________________ > Haskell-Cafe mailing list > [email protected] > http://www.haskell.org/mailman/listinfo/haskell-cafe
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