OCaml -- simple infix range op.

simple_range.ml

let ( -- ) x y = 
    let step_y = match y > x with 
    | true -> ( fun n -> n - 1 )
    | false -> ( fun n -> n + 1 ) 
    in 
    let rec mklist x y ll = 
        if x == y then y::ll 
        else mklist x (step_y y) (y::ll) 
    in
    mklist x y [];;