Haskell prefix unary operator form

Question

In GHCi:

• Prelude> (+3) 2
  5
• Prelude> (* 3) 2
  6
• Prelude> (/ 3) 2
  0.666666666666666666
• Prelude> (-3) 2
  There is no instance for (Num (t → t1))
   arising from the literal it ': it = (- 3) 23' at <interactive>:1:2
Possible fix: add an instance declaration for (Num (t -> t1))
In the expression: 3
In the expression: (- 3) 2
In the definition of

How can I fix the latter so that it returns -1?

Answer 1

Haskell grammar does not allow you to use -. Use the function instead subtract:

(subtract 3) 2

Answer 2

grddev, Haskell 98 Report:

-e , Haskell, negate (e). - - ; . - negate, . - .

, , : , - , :info (+) :info (-) .

subtract, grddev, infix:

Prelude> let (#) = (-)
Prelude> (# 3) 2
-1

subtract , , .

Answer 3

(-) 3 2

1. -1, 3 -, ,

flip (-) 3 2

Answer 4

, :

(+ -3)

, .