From 0672519cba35953cc86e93ae1b4f697c003db712 Mon Sep 17 00:00:00 2001
From: Kevin Hagerty <kevin.e.hagerty@gmail.com>
Date: Wed, 9 Sep 2020 23:38:02 -0400
Subject: [PATCH 1/2] Fix start, init, concat, take, head

Fix use of start and end values for start(), init(), concat() and take().
Also fix head to work correctly.
---
 episode_58/class-list/src/index.js | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/episode_58/class-list/src/index.js b/episode_58/class-list/src/index.js
index 9d14040..3496974 100644
--- a/episode_58/class-list/src/index.js
+++ b/episode_58/class-list/src/index.js
@@ -69,11 +69,11 @@ class List {
   }
 
   take(count) {
-    return new List(this.fnGenerator, 0, count);
+    return new List(this.fnGenerator, this.start, this.start + count);
   }
 
   head() {
-    return this.generator.next().value;
+    return this.take(1).get(0);
   }
 
   tail() {
@@ -81,7 +81,7 @@ class List {
   }
 
   init() {
-    return new List(this.fnGenerator, this.start, this.end - 1);
+    return new List(this.fnGenerator, this.start, this.length() - 1 );
   }
 
   get(index) {
@@ -139,7 +139,7 @@ class List {
         yield* list.entries();
       }
     }
-    return new List(concatGenerator.bind(this), this.start, this.end);
+    return new List(concatGenerator.bind(this));
   }
 
   zipWith(zipFn, list) {
@@ -237,7 +237,7 @@ class List {
     return new List(listFn.bind(this));
   }
 
-  slice(start, end) {
+  slice(start = this.start, end = this.end ) {
     return new List(this.fnGenerator, start, end);
   }
 

From 407f42c898b5630080d0747f762b3054d19de9d7 Mon Sep 17 00:00:00 2001
From: Kevin Hagerty <kevin.e.hagerty@gmail.com>
Date: Wed, 9 Sep 2020 23:57:01 -0400
Subject: [PATCH 2/2] memoize scan left

---
 episode_58/class-list/src/index.js | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/episode_58/class-list/src/index.js b/episode_58/class-list/src/index.js
index 3496974..101e9e5 100644
--- a/episode_58/class-list/src/index.js
+++ b/episode_58/class-list/src/index.js
@@ -69,11 +69,11 @@ class List {
   }
 
   take(count) {
-    return new List(this.fnGenerator, this.start, this.start + count);
+    return new List(this.fnGenerator, 0, count);
   }
 
   head() {
-    return this.take(1).get(0);
+    return this.generator.next().value;
   }
 
   tail() {
@@ -81,7 +81,7 @@ class List {
   }
 
   init() {
-    return new List(this.fnGenerator, this.start, this.length() - 1 );
+    return new List(this.fnGenerator, this.start, this.end - 1);
   }
 
   get(index) {
@@ -139,7 +139,7 @@ class List {
         yield* list.entries();
       }
     }
-    return new List(concatGenerator.bind(this));
+    return new List(concatGenerator.bind(this), this.start, this.end);
   }
 
   zipWith(zipFn, list) {
@@ -237,7 +237,7 @@ class List {
     return new List(listFn.bind(this));
   }
 
-  slice(start = this.start, end = this.end ) {
+  slice(start, end) {
     return new List(this.fnGenerator, start, end);
   }
 
@@ -262,7 +262,8 @@ class List {
         yield accumulator;
       }
     }
-    return new List(scanLGenerator.bind(this), this.start, this.end);
+    // a poor way of memoization -- using toList and fromList
+    return List.fromList( new List(scanLGenerator.bind(this), this.start, this.end).toList() );
   }
 
   scanr(scanFn, accumulator) {