On 13/01/14 18:42, Krzysztof Gogolewski wrote: > Hello, > > As discussed on ghc-devs, I propose to enable -XTypeHoles in GHC by > default. Rationale: > > (1) This way holes are far easier to use; just entering "_" allows to check > type of a subexpression, no need of adding "-XTypeHoles". > > (2) This affects error messages only; i.e. the set of programs that compile > stays the same - Haskell 2010. The only exception is that if you use > -fdefer-type-errors, then a program with a hole compiles, but this seems > fine with philosophy of -fdefer-type-errors. > > If so: would you like it to be in 7.8 or wait a cycle? My preference is > 7.8, two people (John and Richard) suggested 7.10. > > -KG >
Sounds good. Are there plans to allow TypeHoles to actually sit in place of types? In the past I did ``` data Hole hole :: Hole hole = undefined foo :: Integer -> Integer foo x = hole bar :: Integer -> Hole bar x y = x + y ``` to cause type errors that could guide me. I now don't have to resort to the first use in ‘foo’ but I still have to define my own Hole type in ‘bar’. -- Mateusz K. _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
