CODEWITHSUNDEEP
haskelllambda-calculus
UQT
UQT

Reputation: 111

Haskell/lambda calculus types example

Suppose that the Haskell or lambda calculus presents the following function types:

A -> B -> C

(A -> B) -> C

How are these two different?

Upvotes: 1

Views: 593

Answers (2)

J. Abrahamson
J. Abrahamson

Reputation: 74344

The first is a function from A to a (a function from B to C). The second is a function from (functions from A to B) to C. The first "takes two arguments" the second "takes one argument". The first is a normal function, the second is a "higher order function".

Upvotes: 4

us2012
us2012

Reputation: 16253

Here are two example functions with your types that will help you figure out how these are different:

valatzero :: Num a => (a -> t) -> t
valatzero f = f 0

plus :: Num a => a -> a -> a
plus x y = x + y

Upvotes: 0

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