diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/ur/list.ur | 13 | ||||
-rw-r--r-- | lib/ur/list.urs | 1 |
2 files changed, 14 insertions, 0 deletions
diff --git a/lib/ur/list.ur b/lib/ur/list.ur index 354ef132..3153cc32 100644 --- a/lib/ur/list.ur +++ b/lib/ur/list.ur @@ -322,6 +322,19 @@ val nth [a] = nth end +fun replaceNth [a] (ls : list a) (n : int) (v : a) : list a = + let + fun repNth (ls : list a) (n : int) (acc : list a) = + case ls of + [] => rev acc + | x :: ls' => if n <= 0 then + revAppend acc (v :: ls') + else + repNth ls' (n-1) (x :: acc) + in + repNth ls n [] + end + fun assoc [a] [b] (_ : eq a) (x : a) = let fun assoc' (ls : list (a * b)) = diff --git a/lib/ur/list.urs b/lib/ur/list.urs index c23bf840..9ad738f1 100644 --- a/lib/ur/list.urs +++ b/lib/ur/list.urs @@ -72,6 +72,7 @@ val mapQueryPartialM : tables ::: {{Type}} -> exps ::: {Type} -> t ::: Type val sort : a ::: Type -> (a -> a -> bool) (* > predicate *) -> t a -> t a val nth : a ::: Type -> list a -> int -> option a +val replaceNth : a ::: Type -> list a -> int -> a -> list a (** Association lists *) |