type lambda = V of var | P of (var * lambda) | C of (lambda * lambda)

and var = string

let rec check (lambda : lambda) : bool =
  match lambda with V _ -> false | P (a, b) -> true | C (a, b) -> true

type lambda = V of var | P of (var * lambda) | C of (lambda * lambda)

and var = string

let rec check (lambda : lambda) : bool =
  match lambda with V _ -> false | P (a, b) -> true | C (a, b) -> true
