Data commit

Task/Look-and-say-sequence/F-Sharp/look-and-say-sequence-1.fs

@@ -0,0 +1,20 @@
+let rec brk p lst =
+  match lst with
+  | [] -> (lst, lst)
+  | x::xs ->
+    if p x
+    then ([], lst)
+    else
+      let (ys, zs) = brk p xs
+      (x::ys, zs)
+
+let span p lst = brk (not << p) lst
+
+let rec groupBy eq lst =
+  match lst with
+  | [] ->  []
+  | x::xs ->
+    let (ys,zs) = span (eq x) xs
+	(x::ys)::groupBy eq zs
+
+let group lst : list<list<'a>> when 'a : equality = groupBy (=) lst

Task/Look-and-say-sequence/F-Sharp/look-and-say-sequence-2.fs

@@ -0,0 +1,10 @@
+let lookAndSay =
+  let describe (xs: char list) =
+    List.append (List.ofSeq <| (List.length xs).ToString()) [List.head xs]
+  let next xs = List.collect describe (group xs)
+  let toStr xs = String (Array.ofList xs)
+  Seq.map toStr <| Seq.unfold (fun xs -> Some (xs, next xs)) ['1']
+
+let getNthLookAndSay n = Seq.nth n lookAndSay
+
+Seq.take 10 lookAndSay