OCaml how to manipulate tuples?

Question

Let's say I have a tuple:

let x = (1,3)

I want to add 1 to only the first value of the tuple. How would I do that?

Answer 1

您使用模式匹配来解构元组，然后构造更新的元组：

let (x1, x2) = x in (x1 + 1, x2)

Answer 2

Patterm matching is a typical idiom. Another way would be with fst and snd :

# let x = (1,3);;
val x : int * int = (1, 3)
# let y = (fst x + 1, snd x);;
val y : int * int = (2, 3)