def CheckedSub.value

bend-collections-laws-math@1.0.0.0 · spec/math/fixed.bend:89

import Base

89def CheckedSub.value(~T: Data, ~val: T -> Nat, ~f: @+x: T -> @+y: T -> Maybe<&2, T>, +a: T, +b: T) -> Type:
90  {mval(~T, ~val, f(a, b)) == keep(Nat.is_le(val(b), val(a)), Nat.sub(val(a), val(b))) : Maybe<&2, Nat>}