CODEWITHSUNDEEP
typesparametersf#
Shredderroy
Shredderroy

Reputation: 2920

In F#, how to pass a type name as a function parameter?

I would like to pass a type name (such as int, or string, or even the name of a user-defined type) as a function parameter. Currently I am doing the following:

type IntegerOrIntegerList =
    | Integer of int
    | IntegerList of int list

let f (n : int) (d : 'T) : IntegerOrIntegerList =
    match (box d) with
    | :? int as i -> Integer(n)
    | _ -> IntegerList([0 .. n])

But the presence of d above is adventitious. What would be the idiomatic F# way to express the above logic?

Thanks in advance for your help.

Upvotes: 3

Views: 2724

Answers (1)

Daniel
Daniel

Reputation: 47914

You could use a type arg:

let f<'T> (n : int) =
  if typeof<'T> = typeof<int> then Integer(n)
  else IntegerList([0 .. n])

Upvotes: 9

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