import Data.Error
import Text => qualified join
-:: BM a b = {t :: a->b, f :: b->a, t2 :: A.c t:(t c a)->t c b, f2 :: A.c t:(t b c)->t a c}
+:: BM a b =
+ { t :: a->b
+ , f :: b->a
+ , t2 :: A.c t:(t c a)->t c b
+ , f2 :: A.c t:(t b c)->t a c
+ }
bm = {t = id, f = id, t2 = id, f2 = id}
:: Action b a