self-host: make it the only compile path; drop the bootstrap as a selectable path

eval-toplevel now routes every compiled form through backend/compile-and-eval
(analyzer -> IR -> Janet back end). The bootstrap compiler (compile-ast) stays
only to bootstrap jolt.ir/jolt.analyzer in backend/compile-load. Dropped the
:selfhost? flag and JOLT_SELFHOST env plumbing — self-host is the default.

Three correctness fixes the full-suite-under-self-host sweep exposed:
- analyzer/back end: recur into a variadic arity now compiles. The arity fn
  gets an ordinary positional rest param (the collected seq), with a dispatch
  wrapper, so (recur fixed... rest-seq) is a clean self-call like Clojure --
  instead of punting to the interpreter, which hangs on this (jolt-4df).
- host_iface: interop heads (.foo/.-field/Foo.) and ns-management forms
  (all-ns, create-ns, resolve, ...) now mark uncompilable so they fall back
  instead of compiling to a bad call.
- back end: named-fn self-reference ((fn self [n] ... (self ...))) binds the
  fn name via a var.

Full unit+integration suite green; clojure-test-suite battery holds 3913.

src/jolt/api.janet

@@ -32,7 +32,8 @@
   opts may contain:
     :namespaces — map of {ns-name → {sym → value, ...}, ...}
     :mutable?   — use Janet mutable data structures instead of persistent
-    :compile?   — enable compilation of Clojure forms to Janet
+    :compile?   — compile Clojure forms via the self-hosted pipeline (analyzer ->
+                  IR -> Janet back end), falling back to the interpreter as needed
     :paths      — extra source roots to search for namespaces (after the stdlib)"
   [&opt opts]
   (default opts {})

src/jolt/backend.janet

@@ -49,15 +49,25 @@
     (array/push binds (emit ctx (in p 1))))
   ['let (tuple/slice binds) (emit ctx (node :body))])
 
-# A named Janet fn whose name is the arity's recur target, so recur is a
-# self-call (Janet tail-calls it).
+# An arity compiles to a named Janet fn whose name is its recur target, so recur
+# is a self-call (Janet tail-calls it). The rest param is an ORDINARY positional
+# param holding a seq (not Janet `&`), so `(recur fixed... rest-seq)` re-enters
+# the way Clojure recur into a variadic arity does (rebinds the rest seq directly,
+# no re-collection). The dispatch wrapper (emit-fn-body) collects the call's args.
 (defn- emit-arity-fn [ctx ar]
   (def ps @[])
   (each pn (vview (ar :params)) (array/push ps (symbol pn)))
-  (when (ar :rest) (array/push ps '&) (array/push ps (symbol (ar :rest))))
-  (if (ar :recur-name)
-    ['fn (symbol (ar :recur-name)) (tuple/slice ps) (emit ctx (ar :body))]
-    ['fn (tuple/slice ps) (emit ctx (ar :body))]))
+  (when (ar :rest) (array/push ps (symbol (ar :rest))))
+  ['fn (symbol (ar :recur-name)) (tuple/slice ps) (emit ctx (ar :body))])
+
+# Invoke an arity's fn with args pulled from the dispatch tuple: fixed params by
+# index, rest as a slice from n-fixed on.
+(defn- emit-arity-invoke [ctx ar jargs]
+  (def nfixed (length (vview (ar :params))))
+  (def call @[(emit-arity-fn ctx ar)])
+  (for i 0 nfixed (array/push call ['in jargs i]))
+  (when (ar :rest) (array/push call ['tuple/slice jargs nfixed]))
+  (tuple/slice call))
 
 (defn- emit-loop [ctx node]
   (def L (symbol (node :recur-name)))
@@ -86,24 +96,43 @@
     ['defer (emit ctx (node :finally)) core]
     core))
 
-(defn- emit-fn [ctx node]
+(defn- emit-fn-body [ctx node]
   (def arities (vview (node :arities)))
-  (if (= 1 (length arities))
+  (def multi (> (length arities) 1))
+  (cond
+    # Single fixed arity (the hot case): emit the arity fn directly — its name is
+    # the recur target, no dispatch overhead.
+    (and (not multi) (not ((first arities) :rest)))
     (emit-arity-fn ctx (first arities))
-    # Multi-arity: dispatch on arg count; fixed arities match exactly, the
-    # variadic one matches >= its fixed count. apply spreads the captured args
-    # into the chosen arity fn (whose own & collects any rest).
+    # Single variadic arity: a thin wrapper collects the call's args so the rest
+    # seq can be built, then hands off to the arity fn.
+    (not multi)
+    (let [jargs (gsym)]
+      ['fn ['& jargs] (emit-arity-invoke ctx (first arities) jargs)])
+    # Multi-arity: dispatch on arg count. Fixed arities match exactly; the (one)
+    # variadic arity matches >= its fixed count.
     (let [jargs (gsym)
           nsym (gsym)
           cf @['cond]]
       (each ar arities
         (def nfixed (length (vview (ar :params))))
         (array/push cf (if (ar :rest) [>= nsym nfixed] [= nsym nfixed]))
-        (array/push cf [apply (emit-arity-fn ctx ar) jargs]))
+        (array/push cf (emit-arity-invoke ctx ar jargs)))
       (array/push cf ['error "wrong number of args passed to fn"])
       ['fn ['& jargs]
        ['do ['def nsym ['length jargs]] (tuple/slice cf)]])))
 
+# A named fn (fn self [..] .. (self ..)) references itself by name. The analyzer
+# binds that name as a local; bind it here to the fn value via a var (set before
+# any call, so the captured closure sees it — same scheme as emit-loop). recur
+# stays a separate self-call to the arity fn; this only covers by-name self-refs.
+(defn- emit-fn [ctx node]
+  (def body (emit-fn-body ctx node))
+  (if (node :name)
+    (let [s (symbol (node :name))]
+      ['do ['var s nil] ['set s body] s])
+    body))
+
 (defn- direct-call? [fnode]
   (case (fnode :op) :var true :local true :fn true :host true false))
 

src/jolt/host_iface.janet

@@ -65,6 +65,9 @@
              "alter-meta!" "reset-meta!" "disj" "set?" "satisfies?"
              "protocol-dispatch" "register-method" "make-reified" "prefer-method"
              "remove-method" "remove-all-methods" "get-method" "methods"
+             # ns-management forms dispatched by the interpreter (not core vars)
+             "create-ns" "remove-ns" "find-ns" "all-ns" "the-ns" "resolve"
+             "ns-resolve" "ns-aliases" "ns-imports" "ns-interns"
              "read-string" "macroexpand-1" "defonce" "ns" "in-ns" "require"
              "import" "use" "refer" "defrecord" "defprotocol" "definterface"
              "reify" "proxy" "extend-type" "extend-protocol" "extend" "gen-class"
@@ -72,7 +75,18 @@
       (put t n true))
     t))
 
-(defn h-special? [name] (if (get special-names name) true false))
+# Interop-shaped heads the interpreter lowers but the back end doesn't model:
+#   (.method obj …) / (.-field obj)  — member access (name starts with ".")
+#   (Foo. …)                          — constructor (name ends with "." )
+# Treated as special so the analyzer marks them uncompilable and falls back.
+(defn- interop-head? [name]
+  (def n (length name))
+  (and (> n 1)
+       (or (= (string/slice name 0 1) ".")
+           (= (string/slice name (- n 1)) "."))))
+
+(defn h-special? [name]
+  (if (or (get special-names name) (interop-head? name)) true false))
 
 # The namespace being compiled. NOT ctx-current-ns directly: the interpreter
 # rebinds current-ns to a fn's defining ns while that fn runs, so an interpreted

src/jolt/loader.janet

@@ -3,8 +3,8 @@
 # Supports in-memory bytecode caching when :compile? is enabled.
 
 (use ./reader)
-(use ./compiler)
 (use ./evaluator)
+(import ./backend :as backend)
 
 # Stateful / context-modifying forms always interpret: they mutate the context
 # (namespaces, macros, types, multimethods, dynamic vars, …) in ways the compiler
@@ -25,15 +25,12 @@
 
 (defn eval-toplevel
   "Evaluate one top-level form for ctx, honoring :compile?. Stateful forms always
-  interpret; otherwise the form is compiled and run, falling back to the
-  interpreter when the compiler can't handle it. Only the compile step is guarded
-  — runtime errors in compiled code propagate (no double-eval, no hidden errors)."
+  interpret; otherwise the form runs through the self-hosted compile pipeline
+  (portable Clojure analyzer -> IR -> Janet back end), which falls back to the
+  interpreter for forms it can't compile. Only the compile step is guarded —
+  runtime errors in compiled code propagate (no double-eval, no hidden errors)."
   [ctx form]
-  (defn try-compile []
-    (let [compiled (protect (compile-ast form ctx))]
-      (if (compiled 0)
-        (eval-compiled (compiled 1) ctx)
-        (eval-form ctx @{} form))))
+  (defn try-compile [] (backend/compile-and-eval ctx form))
   (if (get (ctx :env) :compile?)
     (if (array? form)
       # A call/list: compile it unless its head is a stateful special form.

src/jolt/main.janet

@@ -11,9 +11,10 @@
 
 (def jolt-version "0.1.0")
 
-# Compile by default: the shipped runtime compiles each form to Janet bytecode
-# (hybrid — forms the compiler can't handle fall back to the interpreter, so the
-# result always matches the interpreter; see compiler.janet / loader/eval-toplevel).
+# Compile by default: the shipped runtime runs each form through the self-hosted
+# pipeline (portable Clojure analyzer -> IR -> Janet back end) to native bytecode
+# (hybrid — forms the analyzer can't compile fall back to the interpreter, so the
+# result always matches the interpreter; see backend.janet / loader/eval-toplevel).
 # Set JOLT_INTERPRET=1 to force the tree-walking interpreter (debugging / A-B).
 (def compile-default? (not (= "1" (os/getenv "JOLT_INTERPRET"))))
 (def ctx (init {:compile? compile-default?}))