lang_2023/tests/typeclasses.lang

typeclass \default =
  & default : -> \default

typeclass \ord[#eq] =
  & var is-less-then : \ord -> \bool

typeclass \d[#a #b #c] 'a 'b =
  & var do-something : -> (& 'a & 'b)

typeclass \e 'a =
  & var do-something : -> 'a

decl ( == ) 'a[#ord] : 'a -> 'a -> \bool
def ( == ) : a b = a..is-equal-to: b

decl ( != ) 'a[#ord] : 'a -> 'a -> \bool
def ( != ) : a b = not: (a == b)

decl ( < ) 'a[#ord] : 'a -> 'a -> \bool
def ( < ) : a b = a..is-less-then: b

decl ( > ) 'a[#ord] : 'a -> 'a -> \bool
def ( > ) : a b = not: (a <= b)

decl ( <= ) 'a[#ord] : 'a -> 'a -> \bool
def ( <= ) : a b = a < b ||. a == b

decl ( >= ) 'a[#ord] : 'a -> 'a -> \bool
def ( >= ) : a b = not: (a < b)