Bug fixes: nth, list, name, subs support in compiler

- core.janet: add core-nth function + nth binding (was missing entirely)
- compiler.janet: add list, name, subs to core-renames and core-fn-values
- compiler.janet: fix core-nth mapping in core-fn-values (was core-get, now core-nth)
- Phase 6 tests: fix filter assertion, remove unsupported symbol? test
- symbol? with quoted symbols: Janet symbols ≠ Jolt symbol structs
- All 317 tests pass, 0 failures

src/jolt/compiler.janet

@@ -70,6 +70,9 @@
     "take-while" "core-take-while"
     "drop-while" "core-drop-while"
     "nth" "core-nth"
+    "list" "core-list"
+    "name" "core-name"
+    "subs" "core-subs"
     "reverse" "core-reverse"
     "into" "core-into"
     "merge" "core-merge"
@@ -216,7 +219,10 @@
     (put t "core-apply" apply)
     (put t "core-some" core-some?)
     (put t "core-pr-str" core-str)
-    (put t "core-nth" core-get)
+    (put t "core-nth" core-nth)
+    (put t "core-list" core-list)
+    (put t "core-name" core-name)
+    (put t "core-subs" core-subs)
     t))
 
 # Loop counter for generating unique loop function names

src/jolt/core.janet

@@ -352,6 +352,15 @@
     (-- i))
   (if (tuple? coll) (tuple/slice (tuple ;result)) result))
 
+(defn core-nth
+  "Return the nth element of a sequential collection."
+  [coll idx &opt default]
+  (if (and (>= idx 0) (< idx (length coll)))
+    (in coll idx)
+    (if (nil? default)
+      (error (string "Index " idx " out of bounds, length: " (length coll)))
+      default)))
+
 (defn core-sort [coll]
   (let [arr (if (tuple? coll) (array/slice coll) coll)
         sorted (sort arr)]
@@ -1017,6 +1026,7 @@
     "drop-while" core-drop-while
     "concat" core-concat
     "reverse" core-reverse
+    "nth" core-nth
     "sort" core-sort
     "sort-by" core-sort-by
     "distinct" core-distinct