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authorGravatar Adam Chlipala <adam@chlipala.net>2018-04-14 15:15:07 -0400
committerGravatar Adam Chlipala <adam@chlipala.net>2018-04-14 15:15:07 -0400
commit0cadb1a719bc515af2449ac966e545a6599aee4d (patch)
treea350817dec17293fa409151d868ec6a4f87f3a8c
parent1fef19035d2f3388e9ab0dad1889a4cad5c1ca3e (diff)
List.findM
-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 a7296552..95d6fbc8 100644
--- a/lib/ur/list.ur
+++ b/lib/ur/list.ur
@@ -255,6 +255,21 @@ fun find [a] f =
find'
end
+fun findM [m] (_ : monad m) [a] f =
+ let
+ fun find' ls =
+ case ls of
+ [] => return None
+ | x :: ls =>
+ b <- f x;
+ if b then
+ return (Some x)
+ else
+ find' ls
+ in
+ find'
+ end
+
fun search [a] [b] f =
let
fun search' ls =
diff --git a/lib/ur/list.urs b/lib/ur/list.urs
index 37cbe442..fe730152 100644
--- a/lib/ur/list.urs
+++ b/lib/ur/list.urs
@@ -60,6 +60,8 @@ val mem : a ::: Type -> eq a -> a -> t a -> bool
val find : a ::: Type -> (a -> bool) -> t a -> option a
+val findM : m ::: (Type -> Type) -> monad m -> a ::: Type -> (a -> m bool) -> t a -> m (option a)
+
val search : a ::: Type -> b ::: Type -> (a -> option b) -> t a -> option b
val all : a ::: Type -> (a -> bool) -> t a -> bool