I have searched for some time and I can't find a solution. It's probably a simple syntax issue that I can't figure out.
I have a type:
# type ('a, 'b) mytype = 'a * 'b;;
And I want to create a variable of type string string sum.
# let (x:string string mytype) = ("v", "m");;
Error: The type constructor mytype expects 2 argument(s),
but is here applied to 1 argument(s)
I've tried different way of putting parenthesis around type parameters, I get pretty much the same error.
It works, however, with single parameter types so I guess there's some syntax I don't know.
# type 'a mytype2 = string * 'a;;
# let (x:string mytype2) = ("hola", "hello");;
val x : string mytype2 = ("hola", "hello")
Can someone, please, tell me how to do this with two parameters?
You should write
let (x: (string, string) mytype) = ("v", "m");;
That is mytype parameter is a couple. You can even remove unneeded parentheses:
let x: (string, string) mytype = "v", "m";;