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I've seen this type before without knowing what it means. Does it mean something and/or does it have a name?
Prelude> :m Data.Functor
Prelude Data.Functor> :t flip . (flip (<$>))
flip . (flip (<$>))
:: Functor ((->) b) => (b -> a) -> b -> (a -> c) -> c
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(vii) The symbol '∉' stands for 'does not belongs to' also for 'is not an element of'. Therefore, x ∉ A will read as 'x does not belongs to set A' or 'x is not an element of the set A'.
In set theory, a subset is denoted by the symbol ⊆ and read as 'is a subset of'. Using this symbol we can express subsets as follows: A ⊆ B; which means Set A is a subset of Set B. Note: A subset can be equal to the set. That is, a subset can contain all the elements that are present in the set.
:'( means "Crying" or "Sad." This icon is typically used after receiving sad news. When typed, the colon represents eyes, the apostrophe represents a tear, and the open-bracket represents a sad mouth.
The symbol "⊂" means "is a proper subset of". Example. Since all of the members of set A are members of set D, A is a subset of D. Symbolically this is represented as A ⊆ D. Note that A ⊆ D implies that n(A) ≤ n(D) (i.e. 3 ≤ 6).
Actually, ((->) a) is not a type but a partially applied type constructor.
Just like functions, type constructors can be partially applied in Haskell.
You can check the kind of something in GHCi:
ghci> :k (->)
(->) :: * -> * -> *
ghci> :k (->) Int
(->) Int :: * -> *
All values have types of kind *; type constructors have kinds like * -> *, * -> * -> *, etc.
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