explicitly define Statically Resolved Type Parameters

Question

How to Explicitly define Statically Resolved Type Parameters of an inline function?

something like this:

 let inline add<^a,^b,^c> (x:^a) (y:^b) :^c = x + y

Answer 1

You need to do something like:

let inline add< ^a, ^b, ^c when (^a or ^b) : (static member (+) : ^a * ^b -> ^c)> x y = 
    ((^a or ^b) : (static member (+) : ^a * ^b -> ^c)(x,y))

Note the following caveats:

• You need to insert a space before the first occurrence of ^a, since otherwise the compiler can't parse the two characters "<^".
• I wasn't able to use the (+) operator on the right hand side directly (I got an ugly error message) - I needed to use a member invocation expression instead.  This may be a bug.