Question

So let’s say you have a variable n.

You want to check if its an integer, or even better yet check what type it is.

I know there is a function in haskell, isDigit that checks if it is a char.

However is there a function that checks if n is in integer, or even better, gives the type of n?

Answer 1

If you are using an interactive Haskell prompt (like GHCi) you can type :t <expression> and that will give you the type of an expression.

e.g.

Prelude> :t 9

gives

9 :: (Num t) => t

or e.g.

Prelude> :t (+)

gives

(+) :: (Num a) => a -> a -> a