Would keyword arguments conflict with currying in Haskell?

I think I would restrict it to functions having either keyword arguments or positional arguments, so forbidding a combination of the two. In that case you could just consider a function with keyword arguments to be a function from a record type. For example my imagined syntax would be:

magnitude :: {x :: Int, y :: Int} -> Double
magnitude {x = x, y = y} = sqrt (fromIntegral (x * x + y * y))

That could be desugared into:

data MagnitudeArg = MkMagnitudeArg { x :: Int, y :: Int }

magnitude :: MagnitudeArg -> Double
magnitude MkMagnitudeArg {x = x, y = y} = sqrt (fromIntegral (x * x + y * y))

In the Purescript Haskell dialect you can already write such functions using anonymous records:

magnitude :: {x :: Number, y :: Number} -> Number
magnitude {x, y} = sqrt (x * x + y * y)

And there is a proposal to add support for it to GHC (although it is a lot more ambitious):

github.com/ghc-proposals/ghc-proposals

Add Structural Types (Row Polymorphism) (#180)

master ← jvanbruegge:row-polymorphism

opened 09:22AM - 09 Nov 18 UTC

        jvanbruegge
      

+201 -0

Record types in Haskell are just syntactic sugar over normal product types, this… prevents us from specifying functions that work for certain structures of records. Rendered