Defaulting?

上記のHypersetを試していて発見したGHCiの挙動。

*Hyperset> :t let x = singleton (Right x) in x
let x = singleton (Right x) in x :: forall a. (Ord a) => Set a
*Hyperset> let x = singleton (Right x)
*Hyperset> :t x
x :: Set Integer
*Hyperset> let x :: Set Char; x = singleton (Right x)
*Hyperset> :t x
x :: Set Char