3dafa60e65
Phase 3 batch 6 (jolt-1j0). binding installs an array-map var->value thread frame and restores it on exit via try/finally. Dynamic rebinding is seen by called fns. This completes the cleanly-portable safe macros (19 total). conformance 228/228 x3, full suite green.
136 lines
5.9 KiB
Clojure
136 lines
5.9 KiB
Clojure
;; clojure.core — macro tier. Macros expressed in Clojure (defmacro + syntax-quote)
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;; rather than as hand-built Janet form-transformers. Loaded after the fn tiers,
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;; so a macro here may use any already-frozen core fn/macro.
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;;
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;; IMPORTANT — only macros NOT used by the self-hosted compiler (jolt-core/jolt/*)
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;; or by the earlier overlay tiers belong here; those (and/or/when/when-not/
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;; when-let/cond/case/doseq/declare/cond->/->) must stay available before this
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;; tier loads, so they remain in Janet for now. Everything here is user-facing.
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;;
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;; Migration: remove the Janet core-X macro fn AND its core-macro-names entry when
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;; moving a macro here (defmacro installs the :macro flag itself).
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(defmacro comment [& body] nil)
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;; Single arglist (Jolt defmacro is single-arity); the optional else defaults nil
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;; via rest-destructuring.
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(defmacro if-not [test then & [else]]
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`(if (not ~test) ~then ~else))
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;; Conditional binding macros: the name is bound ONLY in the taken branch (the
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;; auto-gensym temp# tests the value; the else/empty branch sees the surrounding
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;; scope). temp# is a single template-local gensym — referenced twice, same symbol.
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(defmacro if-let [bindings then & [else]]
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(let [form (bindings 0) tst (bindings 1)]
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`(let [temp# ~tst]
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(if temp# (let [~form temp#] ~then) ~else))))
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(defmacro if-some [bindings then & [else]]
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(let [form (bindings 0) tst (bindings 1)]
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`(let [temp# ~tst]
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(if (some? temp#) (let [~form temp#] ~then) ~else))))
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(defmacro when-some [bindings & body]
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(let [form (bindings 0) tst (bindings 1)]
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`(let [temp# ~tst]
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(if (some? temp#) (let [~form temp#] ~@body) nil))))
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(defmacro while [test & body]
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`(loop [] (when ~test ~@body (recur))))
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(defmacro dotimes [bindings & body]
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(let [i (bindings 0) n (bindings 1)]
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`(let [n# ~n]
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(loop [~i 0]
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(when (< ~i n#) ~@body (recur (inc ~i)))))))
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;; A fresh jolt symbol inside a macro body: (gensym) here resolves to Janet's
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;; builtin (a Janet symbol the destructurer rejects), so round-trip through str.
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(defn- fresh-sym [] (symbol (str (gensym))))
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;; Lazy-safe: take only the head via first (Clojure uses (seq coll), but Jolt's
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;; eager seq would realize an infinite coll like (repeat nil) and hang). Matches
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;; the prior Janet behavior; the nil/false-head distinction waits on Phase 5
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;; laziness.
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(defmacro when-first [bindings & body]
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(let [x (bindings 0) coll (bindings 1)]
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`(when-let [~x (first ~coll)] ~@body)))
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;; doto threads a single fresh-bound value as the first arg of each form (side
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;; effects), returning the value. A shared explicit gensym is needed because the
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;; forms are built outside the let's template.
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(defmacro doto [x & forms]
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(let [g (fresh-sym)
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steps (map (fn [f] (if (seq? f) (apply list (first f) g (rest f)) (list f g))) forms)]
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`(let [~g ~x] ~@steps ~g)))
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;; Threading-with-rebinding macros. The binding pairs are spliced into a TEMPLATE
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;; vector (so core-let sees a tuple form, not a runtime pvec value).
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(defn- thread-binds [g steps]
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(reduce (fn [acc s] (conj (conj acc g) s)) [] (butlast steps)))
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(defmacro as-> [expr name & forms]
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(let [pairs (reduce (fn [acc f] (conj (conj acc name) f)) [] (butlast forms))]
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`(let [~name ~expr ~@pairs] ~(if (empty? forms) name (last forms)))))
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(defmacro some-> [expr & forms]
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(let [g (fresh-sym)
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steps (map (fn [f] `(if (nil? ~g) nil (-> ~g ~f))) forms)]
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`(let [~g ~expr ~@(thread-binds g steps)] ~(if (empty? steps) g (last steps)))))
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(defmacro some->> [expr & forms]
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(let [g (fresh-sym)
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steps (map (fn [f] `(if (nil? ~g) nil (->> ~g ~f))) forms)]
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`(let [~g ~expr ~@(thread-binds g steps)] ~(if (empty? steps) g (last steps)))))
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;; cond-> stays in Janet (the compiler uses it); cond->> (thread-last) is safe.
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(defmacro cond->> [expr & clauses]
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(let [g (fresh-sym)
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steps (map (fn [pair] `(if ~(first pair) (->> ~g ~(second pair)) ~g))
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(partition 2 clauses))]
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`(let [~g ~expr ~@(thread-binds g steps)] ~(if (empty? steps) g (last steps)))))
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(defmacro assert [x & [message]]
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(let [msg (if message message (str "Assert failed: " (pr-str x)))]
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`(when-not ~x (throw (ex-info ~msg {})))))
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(defmacro delay [& body]
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`(make-delay (fn [] ~@body)))
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(defmacro future [& body]
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`(future-call (fn [] ~@body)))
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;; Build the fn* form via a template (a reader-list array): cons/list in a macro
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;; body produce a plist the evaluator can't call as a form.
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(defmacro letfn [fnspecs & body]
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(let [binds (reduce (fn [acc spec] (conj (conj acc (first spec)) `(fn* ~@(rest spec))))
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[] fnspecs)]
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`(let* [~@binds] ~@body)))
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;; Dynamic binding: install a thread-binding frame of var->value (array-map keeps
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;; var-get happy, unlike a phm), restore on exit.
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(defmacro binding [bindings & body]
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(let [pairs (reduce (fn [acc p] (conj (conj acc `(var ~(first p))) (second p)))
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[] (partition 2 bindings))]
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`(let* [frame# (array-map ~@pairs)]
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(push-thread-bindings frame#)
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(try (do ~@body) (finally (pop-thread-bindings))))))
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;; condp: clauses are test-expr result-expr, or test-expr :>> result-fn (calls
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;; result-fn on the truthy (pred test-expr value)); a lone trailing expr is the
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;; default. The recursive emit builds a nested if chain.
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(defmacro condp [pred expr & clauses]
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(let [gp (fresh-sym) ge (fresh-sym)
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emit (fn emit [args]
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(let [n (if (= :>> (second args)) 3 2)
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clause (take n args)
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more (drop n args)
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cn (count clause)]
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(cond
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(= 0 cn) `(throw (ex-info (str "No matching clause: " ~ge) {}))
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(= 1 cn) (first clause)
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(= 2 cn) `(if (~gp ~(first clause) ~ge) ~(second clause) ~(emit more))
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:else `(if-let [p# (~gp ~(first clause) ~ge)]
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(~(nth clause 2) p#)
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~(emit more)))))]
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`(let [~gp ~pred ~ge ~expr] ~(emit clauses))))
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