I think flexibility about the proxy type has become the norm, and we should probably follow that guideline. However, it could theoretically break code.

asProxyTypeOf x (pure "I'm a string")

is currently accepted but would be rejected with the proposed change (since the proxy type isn't fixed, GHC doesn't know that it's Applicative).


On Nov 6, 2016 12:37 PM, "Tom Ellis" <tom-lists-haskell-cafe-2013@jaguarpaw.co.uk> wrote:
Did anything ever come of this proposal to relax the type of asProxyType of?

    https://mail.haskell.org/pipermail/libraries/2014-December/024462.html

i.e. change

    asProxyTypeOf :: a -> Proxy a -> a

to

    asProxyTypeOf :: a -> proxy a -> a

I posted this issue on the Trac

    https://ghc.haskell.org/trac/ghc/ticket/12805

but it was suggested I ask on the libraries list.

Tom
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