From fea0260a7a85f50546cf0e22146e3e8673906db1 Mon Sep 17 00:00:00 2001
From: Jaroslav Tulach <jaroslav.tulach@enso.org>
Date: Fri, 6 Jan 2023 15:38:49 +0100
Subject: [PATCH] Get List.filter and List.init ready for long Lists

---
 .../Base/0.0.0-dev/src/Data/List.enso         | 28 +++++++++++++++----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/distribution/lib/Standard/Base/0.0.0-dev/src/Data/List.enso b/distribution/lib/Standard/Base/0.0.0-dev/src/Data/List.enso
index 6069d72cdda81..4b7a9545a93e1 100644
--- a/distribution/lib/Standard/Base/0.0.0-dev/src/Data/List.enso
+++ b/distribution/lib/Standard/Base/0.0.0-dev/src/Data/List.enso
@@ -290,7 +290,16 @@ type List
     take_start : Integer -> List
     take_start self count = if count <= 0 then Nil else case self of
         Nil -> Nil
-        Cons a b -> Cons a (b.take_start count-1)
+        Cons a b ->
+            go c l fill = if c <= 0 then fill Nil else case l of
+                Nil -> fill Nil
+                Cons a b ->
+                    res = Meta.atom_with_hole (e -> Cons a e)
+                    fill res.value
+                    @Tail_Call go c-1 b res.fill
+            res = Meta.atom_with_hole (e -> Cons a e)
+            go count-1 b res.fill
+            res.value
 
     ## Get the first element from the list.
 
@@ -328,12 +337,21 @@ type List
              example_init = Examples.list.init
     init : List ! Empty_Error
     init self =
-        init_fn x y = case y of
-            Nil -> Nil
-            Cons a b -> Cons x (init_fn a b)
         case self of
             Nil -> Error.throw Empty_Error
-            Cons a b -> init_fn a b
+            Cons a Nil -> Nil
+            Cons a b ->
+                go l fill = case l of
+                    Cons x xs -> case xs of
+                        Nil -> fill Nil
+                        Cons y z ->
+                            res = Meta.atom_with_hole (e -> Cons y e)
+                            fill res.value
+                            @Tail_Call go xs res.fill
+
+                res = Meta.atom_with_hole (e -> Cons a e)
+                go b res.fill
+                res.value
 
     ## Get the last element of the list.