%%% Simple combinators

defn K = \x. \y. x
defn S = \x. \y. \z. x z (y z)
defn I = \x. x
conv S K K = I

% confirming associativity
conv S = \x. \y. \z. (x z) (y z)
conv S = \x. (\y. (\z. ((x z) (y z))))

% cannot omit the parentheses
fail conv S = \x. \y. \z. x z y z