Mercurial > urweb
diff lib/ur/monad.ur @ 1768:a613cae954ca
Some standard library additions from Edward Z. Yang
author | Adam Chlipala <adam@chlipala.net> |
---|---|
date | Sat, 19 May 2012 11:32:12 -0400 |
parents | 18d18a70821e |
children | cbd294994c69 |
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--- a/lib/ur/monad.ur Thu May 17 10:20:24 2012 -0400 +++ b/lib/ur/monad.ur Sat May 19 11:32:12 2012 -0400 @@ -12,6 +12,8 @@ v <- m; return (f v) +val liftM = @@mp + fun foldR [K] [m] (_ : monad m) [tf :: K -> Type] [tr :: {K} -> Type] (f : nm :: Name -> t :: K -> rest :: {K} -> [[nm] ~ rest] => @@ -122,3 +124,8 @@ f [nm] [t] r1.nm r2.nm r3.nm) (fn _ _ _ => return ()) fl + +fun liftM2 [m ::: Type -> Type] (_ : monad m) [a] [b] [c] (f : a -> b -> c) (mx : m a) (my : m b) : m c = + x <- mx; + y <- my; + return (f x y)