What is the “let” keyword in functional languages like F# and OCaml for?

Question

When looking at F#, Ocaml and other functional language code examples I notice that the let keyword is used very often.

• Why do you need it? Why were the langua

Answer 1

In Haskell,

foo = let x = 5
      y = 7
      in z=x+y

is used to make clear that x and y are "private" variables to foo.