24 Mar
2015
24 Mar
'15
2:23 a.m.
On 22/03/2015 at 23:01:47 -0400, David Feuer wrote:
There are a good number of different packages that define either
newtype Fix f = Fix (f (Fix f))
or something equivalent except for naming. Most of the name variation is in the name of the data constructor and/or record selector. This does not look like an ideal situation to me. Most problematically, the only way to convert one to another is with unsafeCoerce.
I think it would be rather nice to choose one canonical place for this definition, and let everyone else use it.
+1 I propose module Data.Fix where newtype Fix f = Fix { unFix :: f (Fix f) } Perhaps too we ought to name and define _ :: (∀ a . f a -> g a) -> Fix f -> Fix g there.