[Haskell-cafe] Naive booleans and numbers - type-checking fails

[Stephen Tetley]

Doesn't the simply typed lambda calculus introduce if-then-else as a
primitive precisely so that it can be typed?

Its not an illuminating answer to your question and I'd welcome
clarification for my own understanding, but I don't think you can
solve the problem without appealing to Haskell's built-in
if-then-else.

Best wishes

Stephen