STDLIB: More stdlib additions.

* list reverse
* enumerate for tuples

std/lists.ucg

@@ -26,6 +26,16 @@ let len = module{
     let result = reduce counter.result 0, (mod.list);
 };
 
+let reverse = module{
+    list = NULL,
+} => {
+    let reducer = macro(acc, item) => {
+        result = [item] + acc,
+    };
+
+    let result = reduce reducer.result [], (mod.list); 
+};
+
 let enumerate = module{
     start = 0,
     step = 1,

std/tests/lists_test.ucg

@@ -15,6 +15,11 @@ assert asserts.equal{
     right=4,
 };
 
+assert asserts.equal{
+    left = list.reverse{list=[0, 1, 2, 3]}.result,
+    right = [3, 2, 1, 0],
+};
+
 assert asserts.equal{
     left=list.enumerate{list=["foo", "bar"]}.result,
     right=[[0, "foo"], [1, "bar"]],

std/tests/tuples_test.ucg

@@ -9,4 +9,9 @@ assert t.asserts{}.equal{
 assert t.asserts{}.equal{
     left = tpl.values{tpl={foo=1, bar=2}}.result,
     right = [1, 2],
+};
+
+assert t.asserts{}.equal{
+    left = tpl.enumerate{tpl={foo=1, bar=2}}.result,
+    right = [["foo", 1], ["bar", 2]],
 };

std/tuples.ucg

@@ -1,4 +1,5 @@
 
+// return a list of the fields in a tuple.
 let fields = module{
     tpl = NULL,
 } => {
@@ -9,6 +10,7 @@ let fields = module{
     let result = reduce reducer.result [], (mod.tpl);
 };
 
+// return a list of the values in a tuple.
 let values = module{
     tpl = NULL,
 } => {
@@ -16,5 +18,15 @@ let values = module{
         result = acc + [value],
     };
 
+    let result = reduce reducer.result [], (mod.tpl);
+};
+
+let enumerate = module{
+    tpl = NULL,
+} => {
+    let reducer = macro(acc, field, value) => {
+        result = acc + [[field, value]],
+    };
+    
     let result = reduce reducer.result [], (mod.tpl);
 };