I am trying to figure out how to define a function that works on multiple types of parameters (e.g. int and int64). As I understand it, function overloading is not possible in F# (certainly the compiler complains). Take for example the following function.
let sqrt_int = function
| n:int -> int (sqrt (float n))
| n:int64 -> int64 (sqrt (float n))
The compiler of course complains that the syntax is invalid (type constraints in pattern matching are not supported it seems), though I think this illustrates what I would like to achieve: a function that operates on several parameter types and returns a value of the according type. I have a feeling that this is possible in F# using some combination of generic types/type inference/pattern matching, but the syntax has eluded me. I've also tried using the :? operator (dynamic type tests) and when clauses in the pattern matching block, but this still produces all sorts errors.
As I am rather new to the language, I may very well be trying to do something impossible here, so please let me know if there is alternative solution.
Overloading is typically the bugaboo of type-inferenced languages (at least when, like F#, the type system isn't powerful enough to contain type-classes). There are a number of choices you have in F#:
For your particular example, I would probably just use method overloading:
type MathOps =
static member sqrt_int(x:int) = x |> float |> sqrt |> int
static member sqrt_int(x:int64) = x |> float |> sqrt |> int64
let x = MathOps.sqrt_int 9
let y = MathOps.sqrt_int 100L