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