Bulat Ziganshin wrote:
Hello Cristiano,
Thursday, June 21, 2007, 4:46:27 PM, you wrote:
class FooOp a b where
foo :: a -> b -> IO ()
instance FooOp Int Double where
foo x y = putStrLn $ (show x) ++ " Double " ++ (show y)
this is rather typical question :) unlike C++ which resolves any
overloading at COMPILE TIME, selecting among CURRENTLY available
overloaded definitions and complaining only when when this overloading
is ambiguous, type classes are the RUN-TIME overloading mechanism
As I understood it, it was at COMPILE TIME (i.e. no type witness)
whenever explicitly type-annotated, implicitly when not exported from a
module, or when inlined at the call site, at least in GHC. Or did I get
this wrong?
Dan
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