!def TRUE = \x y. x
TRUE
!def FALSE = \x y. y
!def IF = \x y z. x y z
IF TRUE t e
!trace
IF TRUE t e
!def NOT = \z x y. z y x
NOT T
NOT F
!def add = \m n f x. m f (n f x)
!def 2 = \f x. f (f x)
add 2 2
!by_value
add 2 2