ghci> let plus_one = (+) 1 ghci> let plus_one = (+ 1)
Either notation will work, but they do subtly different things: in the first case, you get 1 + x, and in the second, you get x + 1. Nevertheless.
Exactly. You can get 1+x with a section, just write it (1+)
Division works the same way.
That's where the subtly different things becomes not so subtle, because if you define two_divided_by_1 = (/) 2 two_divided_by_2 = (/ 2) in the first case you indeed define a function that divides two by the number given, but in the second case it's a function that divides the number given by two. You have to define it like this: two_divided_by_3 = (2 /) Prelude> let two_divided_by_1 = (/) 2 Prelude> let two_divided_by_2 = (/2) Prelude> two_divided_by_1 4 0.5 Prelude> two_divided_by_2 4 2.0 Prelude> let two_divided_by_3 = (2/) Prelude> two_divided_by_3 4 0.5 Prelude>