[Haskell-cafe] Implicit newtype unwrapping

Matthew Pocock matthew.pocock at ncl.ac.uk
Thu Dec 3 06:13:09 EST 2009


Perhaps what you are looking for is a more powerful "defining" semantics?

newtype MyFoo = Foo defining (Foo(..)) -- all class instances that Foo has
are delegated through from MyFoo

Matthew


> not sure if this is what you are thinking at, but everytime I wrap a
> type Foo in a newtype MyFoo to define my own instances (or just for more
> expressiveness code), I wish I had a way to tell the compiler:
> „Please define function myfoo to be the same as foo, with all occurences
> of Foo in its type signature replaced by MyFoo.“
>
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