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authorGravatar Adam Chlipala <adam@chlipala.net>2018-04-14 14:17:31 -0400
committerGravatar Adam Chlipala <adam@chlipala.net>2018-04-14 14:17:31 -0400
commit1fef19035d2f3388e9ab0dad1889a4cad5c1ca3e (patch)
treeab2feca6fc2b56003ce0326ef456e76aae16483d
parent7d4a7a7f92095edfea1cb55a11e037667c2c21da (diff)
List.existsM
-rw-r--r--lib/ur/list.ur15
-rw-r--r--lib/ur/list.urs2
2 files changed, 17 insertions, 0 deletions
diff --git a/lib/ur/list.ur b/lib/ur/list.ur
index cc533676..a7296552 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -204,6 +204,21 @@ fun exists [a] f =
ex
end
+fun existsM [m] (_ : monad m) [a] f =
+ let
+ fun ex ls =
+ case ls of
+ [] => return False
+ | x :: ls =>
+ b <- f x;
+ if b then
+ return True
+ else
+ ex ls
+ in
+ ex
+ end
+
fun foldlMap [a] [b] [c] f =
let
fun fold ls' st ls =
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index fd56679d..37cbe442 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -42,6 +42,8 @@ val filter : a ::: Type -> (a -> bool) -> t a -> t a
val exists : a ::: Type -> (a -> bool) -> t a -> bool
+val existsM : m ::: (Type -> Type) -> monad m -> a ::: Type -> (a -> m bool) -> t a -> m bool
+
val foldlM : m ::: (Type -> Type) -> monad m -> a ::: Type -> b ::: Type
-> (a -> b -> m b) -> b -> t a -> m b