Make ints_of_string generic and move to lib.

lib/aoc.ml

@@ -1,4 +1,6 @@
-let ints_of_string s = List.map int_of_string (Str.split (Str.regexp " +") s)
+let ints_of_string ?(sep = " ") s =
+  List.map int_of_string (Str.split (Str.regexp sep) s)
+
 let distance1 a b = abs (a - b)
 
 let strings_of_file fname =

lib/aoc.mli

@@ -1,6 +1,6 @@
-val ints_of_string : string -> int list
-(** [nums_from_string s] takes a string of space separated integers and gives
-    back a list of the integers. *)
+val ints_of_string : ?sep:string -> string -> int list
+(** [nums_from_string ?sep s] takes a string of integers separated by [sep] and
+    gives back a list of the integers.  By default [sep] is " " *)
 
 val distance1 : int -> int -> int
 (** [distance1 a b] returns the absolute difference between [a] and [b]. *)