Phase 6: comprehensive compile-mode tests + bug fixes

47 new compile-mode tests: collections, math, predicates, comparison,
seq operations (map/filter/reduce/take/drop), special forms (let/if/loop/
try/quote), macros (defn/when/and/or/fn/if-let), complex nesting.

Bugs fixed:
- emit-vector-expr: use (tuple ...) instead of bare tuple
  (Janet eval treats bare tuples as function calls)
- make-symbol: / at position 0 → unqualified symbol
  (was parsing as {:ns "" :name ""})
- core-renames: add missing fn? entry

src/jolt/compiler.janet

@@ -25,6 +25,7 @@
     "some?" "core-some?"
     "string?" "core-string?"
     "number?" "core-number?"
+    "fn?" "core-fn?"
     "keyword?" "core-keyword?"
     "symbol?" "core-symbol?"
     "vector?" "core-vector?"
@@ -664,7 +665,7 @@
   (tuple/slice (tuple ;exprs)))
 
 (defn- emit-vector-expr [items]
-  (def exprs @[])
+  (def exprs @['tuple])
   (each item items (array/push exprs (emit-expr item)))
   (tuple/slice (tuple ;exprs)))
 

src/jolt/reader.janet

@@ -70,7 +70,7 @@
   "Create a Jolt symbol struct."
   [name]
   (let [slash (string/find "/" name)]
-    (if slash
+    (if (and slash (> slash 0))
       {:jolt/type :symbol
        :ns (string/slice name 0 slash)
        :name (string/slice name (+ slash 1))}