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-rw-r--r--lib/ur/list.ur15
1 files changed, 15 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 =