Signed-off-by: Matthias Goergens <[email protected]>
stdext/listext.ml | 4 ++++ stdext/listext.mli | 1 + 2 files changed, 5 insertions(+), 0 deletions(-)
# HG changeset patch # User Matthias Goergens <[email protected]> # Date 1274194687 -3600 # Node ID 3d335a63fbc8bae4f18cddc58544777e6c2b329d # Parent 5ed655dae285df1e9a4beec99e2f3308f56830d7 The module stdext/Listext got a safe_head function that wraps hd in an option type. Signed-off-by: Matthias Goergens <[email protected]> diff --git a/stdext/listext.ml b/stdext/listext.ml --- a/stdext/listext.ml +++ b/stdext/listext.ml @@ -193,6 +193,10 @@ let rec tails = function | [] -> [[]] | (_::xs) as l -> l :: tails xs +let safe_hd = function + | a::_ -> Some a + | [] -> None + let rec replace_assoc key new_value = function | [] -> [] | (k, _) as p :: tl -> diff --git a/stdext/listext.mli b/stdext/listext.mli --- a/stdext/listext.mli +++ b/stdext/listext.mli @@ -176,6 +176,7 @@ module List : val take : int -> 'a list -> 'a list val tails : 'a list -> ('a list) list + val safe_hd : 'a list -> 'a option (** Replace the value belonging to a key in an association list. *) val replace_assoc : 'a -> 'b -> ('a * 'b) list -> ('a * 'b) list
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