fix c[ad]+r when access nil + typececk

jcubic · May 1, 2019 · 53e08fd · 53e08fd
1 parent f55317f
commit 53e08fd
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Showing 4 changed files with 45 additions and 3 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -3,6 +3,8 @@
 * remove `nop` (you can use `(begin undefined)`)
 ### Bug fixes
 * fix unquote-splicing on nil (e.g. processing of `` `(list ,@nil)``)
+* cdr and car should return nil on empty list
+* typecheck and process nil in c[ad]+r functions
 
 ## 0.11.1
 ### Bug fixes

diff --git a/dist/lips.js b/dist/lips.js
@@ -21,7 +21,7 @@
  * http://javascript.nwbox.com/ContentLoaded/
  * http://javascript.nwbox.com/ContentLoaded/MIT-LICENSE
  *
- * build: Wed, 01 May 2019 10:23:31 +0000
+ * build: Wed, 01 May 2019 10:31:05 +0000
  */
 (function () {
 'use strict';
@@ -3381,12 +3381,30 @@ function _typeof(obj) {
     }, "(cons left right)\n\n            Function return new Pair out of two arguments."),
     // ------------------------------------------------------------------
     car: doc(function (list) {
+      if (list === nil) {
+        return nil;
+      }
+
       typecheck('car', list, 'pair');
+
+      if (isEmptyList(list)) {
+        return nil;
+      }
+
       return list.car;
     }, "(car pair)\n\n            Function returns car (head) of the list/pair."),
     // ------------------------------------------------------------------
     cdr: doc(function (list) {
+      if (list === nil) {
+        return nil;
+      }
+
       typecheck('cdr', list, 'pair');
+
+      if (isEmptyList(list)) {
+        return nil;
+      }
+
       return list.cdr;
     }, "(cdr pair)\n\n            Function returns cdr (tail) of the list/pair."),
     // ------------------------------------------------------------------
@@ -4816,6 +4834,12 @@ function _typeof(obj) {
     var name = 'c' + spec + 'r';
     global_env.set(name, doc(function (arg) {
       return chars.reduce(function (list, type) {
+        if (list === nil) {
+          return nil;
+        }
+
+        typecheck(name, list, 'pair');
+
         if (type === 'a') {
           return list.car;
         } else {

diff --git a/dist/lips.min.js b/dist/lips.min.js
diff --git a/src/lips.js b/src/lips.js
@@ -2027,14 +2027,26 @@
             Function return new Pair out of two arguments.`),
         // ------------------------------------------------------------------
         car: doc(function(list) {
+            if (list === nil) {
+                return nil;
+            }
             typecheck('car', list, 'pair');
+            if (isEmptyList(list)) {
+                return nil;
+            }
             return list.car;
         }, `(car pair)
 
             Function returns car (head) of the list/pair.`),
         // ------------------------------------------------------------------
         cdr: doc(function(list) {
+            if (list === nil) {
+                return nil;
+            }
             typecheck('cdr', list, 'pair');
+            if (isEmptyList(list)) {
+                return nil;
+            }
             return list.cdr;
         }, `(cdr pair)
 
@@ -3513,6 +3525,10 @@
         const name = 'c' + spec + 'r';
         global_env.set(name, doc(function(arg) {
             return chars.reduce(function(list, type) {
+                if (list === nil) {
+                    return nil;
+                }
+                typecheck(name, list, 'pair');
                 if (type === 'a') {
                     return list.car;
                 } else {