Just add parentheses around your operator: (<=>) :: Ternary -> Ternary -> Ternary (<=>) T F = F (<=>) T T = T (<=>) T M = M (<=>) F F = T (<=>) F T = F (<=>) F M = M (<=>) M F = M (<=>) M T = M (<=>) M … Read more
As several of the comments have said, this is the Haskell RTS detecting an infinite loop at run-time. It cannot always detect such loops, but in simple cases it can. For example, x = x + 1 will compile just fine, but provoke an exception at run-time. (Incidentally, this is an exception – in particular, … Read more
@~ is coercion application. The angle brackets denote a reflexive coercion of their contained type with role given by the underscored letter. Thus <Nat.Flip x_ap0H>_N is an equality proof that Nat.Flip x_apH is equal to Nat.Flip x_apH nominally (as equal types not just equal representations). PS has a lot of arguments. We look at the … Read more