core: Fix destructure assign from lazy seq

Author: ingydotnet

core/src/ys/std.clj

@@ -946,7 +946,7 @@
 (defn- destructure-vector [V idx]
   (map-indexed
     (fn [i name]
-      (+def-defn name `(get ~idx ~i)))
+      (+def-defn name `(nth ~idx ~i nil)))
     V))
 
 (defn- destructure-map [M idx]
@@ -959,9 +959,8 @@
   (let [root (gensym)]
     `(let [~root ~idx]
        ~@(condf x
-           vector? (destructure-vector x root)
-           list? (destructure-vector x root)
            map? (destructure-map x root)
+           seqable? (destructure-vector x root)
            []))))
 
 (defn- +def-defn [x y]

ys/test/std.t

@@ -401,6 +401,30 @@ test::
     =>: "$what $who"
   want: Hello World
 
+- name: Range destructuring
+  code: |
+    a b c =: range()
+    =>: "$a - $b - $c"
+  want: '0 - 1 - 2'
+
+- name: Short range destructuring
+  code: |
+    a b c =: range(2)
+    =>: +[a b c]
+  want: [0, 1, null]
+
+- name: Range destructuring
+  code: |
+    a b c =: 1 2 3
+    =>: "$a - $b - $c"
+  want: '1 - 2 - 3'
+
+- name: Auto grouping
+  code: |
+    a =: 1 2 3
+    =>: a
+  want: [1, 2, 3]
+
 
 #-------------------------------------------------------------------------------
 done: