Defining a function in GHCi results in different strictness behavior than defining it in a file
When defining a strict composition function in GHCi using
let f .:. g = seq f (seq g (\x -> f (g x)))
(omitting the let makes no difference) and then executing
seq (undefined .:. undefined) ()
this evaluates to
() instead of bottom as I would have expected.
.:. is defined an a file and then loaded in GHCi the same statement evaluates to bottom. This also holds when
.:. is introduced via a let+in instead of a separate let statement.