To open the repl, run the command:
$ stack runCreating a representation for the booleans values
Untyped> let true := λa. λb. a
Untyped> let false := λa. λb. b
Let's make a conditional structure: if <expr> then <expr> else <expr>
Untyped> let ifThenElse := λp. λa. λb. p a b
Executing the code if true then zero else one
Untyped> let zero := λs. λz. z
Untyped> let one := λs. λz. s z
Untyped> ifThenElse true zero one