feat(samples): add quicksort example script

Author: pchalamet

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to FScript are documented in this file.
 
 ## [Unreleased]
 
+- Added `samples/quicksort.fss` with a recursive quicksort example over integer lists.
+
 ## [0.43.0]
 
 

README.md

@@ -115,6 +115,7 @@ dotnet run --project src/FScript --
 Useful samples:
 - [`samples/types-showcase.fss`](samples/types-showcase.fss)
 - [`samples/patterns-and-collections.fss`](samples/patterns-and-collections.fss)
+- [`samples/quicksort.fss`](samples/quicksort.fss)
 - [`samples/tree.fss`](samples/tree.fss)
 - [`samples/mutual-recursion.fss`](samples/mutual-recursion.fss)
 - [`samples/imports-and-exports.fss`](samples/imports-and-exports.fss)

docs/guides/getting-started-tutorial.md

@@ -426,6 +426,7 @@ When embedding, keep this mindset:
 - Sample scripts:
   - [`samples/types-showcase.fss`](../../samples/types-showcase.fss)
   - [`samples/patterns-and-collections.fss`](../../samples/patterns-and-collections.fss)
+  - [`samples/quicksort.fss`](../../samples/quicksort.fss)
   - [`samples/map-matching.fss`](../../samples/map-matching.fss)
   - [`samples/imports-and-exports.fss`](../../samples/imports-and-exports.fss)
 - Specifications index: [`docs/specs/README.md`](../specs/README.md)

samples/quicksort.fss

@@ -0,0 +1,21 @@
+let rec quicksort values =
+  match values with
+  | [] -> []
+  | pivot :: rest ->
+      let smaller = rest |> List.filter (fun value -> value < pivot)
+      let equal = rest |> List.filter (fun value -> value = pivot)
+      let greater = rest |> List.filter (fun value -> value > pivot)
+      (quicksort smaller) @ [pivot] @ equal @ (quicksort greater)
+
+let rec is_sorted values =
+  match values with
+  | [] -> true
+  | [_] -> true
+  | first :: second :: tail -> (first <= second) && (is_sorted (second :: tail))
+
+let input = [9; 2; 8; 2; 4; 7; 1; 6; 3; 5; 3]
+let sorted = quicksort input
+
+print $"quicksort input : {input}"
+print $"quicksort output: {sorted}"
+print $"is sorted       : {is_sorted sorted}"