lean2/tests/lean/revapp.lean

import Int.
definition revapp {A : (Type U)} {B : A -> (Type U)} (a : A) (f : forall (x : A), B x) : (B a) := f a.
infixl 100 |> : revapp

eval 10 |> (fun x, x + 1)
        |> (fun x, x + 2)
        |> (fun x, 2 * x)
        |> (fun x, 3 - x)
        |> (fun x, x + 2)

definition revcomp {A B C: (Type U)} (f : A -> B) (g : B -> C) : A -> C :=
        fun x, g (f x)
infixl 100 #> : revcomp

eval (fun x, x + 1)     #>
     (fun x, 2 * x * x) #>
     (fun x, 10 + x)

definition simple := (fun x, x + 1)     #>
                     (fun x, 2 * x * x) #>
                     (fun x, 10 + x)

check simple
eval simple 10

definition simple2 := (fun x : Int, x + 1) #>
                      (fun x, 2 * x * x)   #>
                      (fun x, 10 + x)
check simple2
eval simple2 (-10)