haskell getting parse error on input `->'

1
votes

I am using ghci compiler with version 7.8.3 on windows 7. I am getting error message showing parse error on input `->'. I have the following code for lambda expression in haskell.

add =\x y -> x+y

2
haskell
Note that =\ is an operator. Since you want to assign a lambda expression to the name add, you need a space: = \ . – Code-Apprentice

2 Answers

5
votes

When defining a function interactively in ghci, you have to bind it using a let like this:

let add = \x y -> x + y
2
votes

I just wrote:

add = \x y -> x + y

main = do
    print $ add 1 2

and it compiled and output 3.

Unless your intent is to practice unsugared code though, I would write it out as:

add x y = x + y

Or

add = (+)

which is "point-free" form.