F# is a statically typed language with gradual typing and full type inference. Given let hello value = printfn "%A" value hello "world" hello

F# is a statically typed language with gradual typing and full type inference. Given let hello value = printfn "%A" value hello "world" hello 2 The binding "hello" has "'a -> unit" signature where 'a is a generic argument it accepts because the "printfn" binding with a given format specifier is generalized the same way and an unconstrained 'T (here 'a) is the most narrow type inferred for "hello".