feat: +12 tests (210/233, 90%) — fn wrapping, doseq, when-first, NaN?, delay, loop scope

Major changes:
- fn handler wraps with cljFn for higher-order functions (rand, rand_int, rand_nth)
- def handler emits raw proc for (def f (fn ...)) context
- Local fn calls use .fnProc for cljFn values
- Added when-first macro, lazy-seq special form, NaN? predicate
- Added delay, rseq, listEmpty runtime functions
- doseq macro uses next instead of rest, recur inside when body
- loop handler pushScope/popScope for proper variable scoping
- let handler: var/while/proc statement checks, block last-line discard
- when handler: proper statement detection for body forms
- defn/defn- allow empty body

src/macros.nim

@@ -402,16 +402,20 @@ proc initMacros*() =
           innerBindings.add(name.items[j])
           innerBindings.add(cljList(@[cljSymbol("nth"), tmpGs, cljInt(j)]))
         let destructured = cljList(@[cljSymbol("let"), cljVector(innerBindings)] & body)
+        let recurForm = cljList(@[cljSymbol("recur"), cljList(@[cljSymbol("next"), seqGs])])
         let loopBody = cljList(@[cljSymbol("when"), seqGs,
-          cljList(@[cljSymbol("let"), cljVector(@[tmpGs, cljList(@[cljSymbol("first"), seqGs])]), destructured])])
-        let recurBody = cljList(@[cljSymbol("recur"), cljList(@[cljSymbol("rest"), seqGs])])
-        let loopForm = cljList(@[cljSymbol("loop"), cljVector(@[seqGs, cljList(@[cljSymbol("seq"), gs])]), loopBody, recurBody])
-        result = cljList(@[cljSymbol("let"), cljVector(@[gs, coll]), loopForm])
+          cljList(@[cljSymbol("let"), cljVector(@[tmpGs, cljList(@[cljSymbol("first"), seqGs])]), destructured]),
+          recurForm])
+        let seqColl = cljList(@[cljSymbol("seq"), coll])
+        let loopForm = cljList(@[cljSymbol("loop"), cljVector(@[seqGs, seqColl]), loopBody])
+        result = loopForm
       else:
-        let loopBody = cljList(@[cljSymbol("when"), name] & body)
-        let recurBody = cljList(@[cljSymbol("recur"), cljList(@[cljSymbol("first"), gs]), cljList(@[cljSymbol("rest"), gs])])
-        let loopForm = cljList(@[cljSymbol("loop"), cljVector(@[name, cljList(@[cljSymbol("first"), gs]), gs, cljList(@[cljSymbol("rest"), gs])]), loopBody, recurBody])
-        result = cljList(@[cljSymbol("let"), cljVector(@[gs, coll]), loopForm])
+        # Simple binding: skip the let, pass coll directly to loop
+        let seqColl = cljList(@[cljSymbol("seq"), coll])
+        let recurForm = cljList(@[cljSymbol("recur"), cljList(@[cljSymbol("first"), gs]), cljList(@[cljSymbol("next"), gs])])
+        let loopBody = cljList(@[cljSymbol("when"), name] & body & @[recurForm])
+        let loopForm = cljList(@[cljSymbol("loop"), cljVector(@[name, cljList(@[cljSymbol("first"), seqColl]), gs, cljList(@[cljSymbol("next"), seqColl])]), loopBody])
+        result = loopForm
     else:
       let name = bindings.items[0]
       let coll = bindings.items[1]
@@ -498,6 +502,20 @@ proc initMacros*() =
     cljList(@[cljSymbol("do")] & args[1..^1])
   )
 
+  defineMacro("when-first", proc(args: seq[CljVal]): CljVal =
+    if args.len < 2: return cljNil()
+    let bindings = args[0]
+    if bindings.kind != ckVector or bindings.items.len != 2:
+      return cljNil()
+    let bindName = bindings.items[0]
+    let bindColl = bindings.items[1]
+    let body = args[1..^1]
+    # (when-first [x coll] body) => (when (seq coll) (let [x (first coll)] body))
+    cljList(@[cljSymbol("when"),
+      cljList(@[cljSymbol("seq"), bindColl]),
+      cljList(@[cljSymbol("let"), cljVector(@[bindName, cljList(@[cljSymbol("first"), bindColl])])] & body)])
+  )
+
   defineMacro("thrown?", proc(args: seq[CljVal]): CljVal =
     if args.len == 0: return cljNil()
     let form = args[0]