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lua: multi-return + unpack at call sites (+10 tests)
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giles
2026-04-24 17:10:52 +00:00
parent 8bfeff8623
commit 2b448d99bc
4 changed files with 187 additions and 8 deletions
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46
lib/lua/runtime.sx
View File

@@ -169,3 +169,49 @@
(if (= t nil) nil (let ((v (get t (str k)))) (if (= v nil) nil v)))))
(define lua-set! (fn (t k v) (assoc t (str k) v)))
(define
lua-multi?
(fn
(v)
(and
(= (type-of v) "list")
(> (len v) 0)
(= (first v) (quote lua-multi)))))
(define
lua-first
(fn
(v)
(cond
((lua-multi? v) (if (> (len v) 1) (nth v 1) nil))
(else v))))
(define
lua-nth-ret
(fn
(v i)
(cond
((lua-multi? v)
(let ((idx (+ i 1))) (if (< idx (len v)) (nth v idx) nil)))
(else (if (= i 0) v nil)))))
(define
lua-pack-build
(fn
(vals i)
(cond
((>= i (len vals)) (list))
((= i (- (len vals) 1))
(let
((last (nth vals i)))
(if (lua-multi? last) (rest last) (list last))))
(else (cons (nth vals i) (lua-pack-build vals (+ i 1)))))))
(define
lua-pack-return
(fn
(vals)
(cond
((= (len vals) 0) (list (quote lua-multi)))
(else (cons (quote lua-multi) (lua-pack-build vals 0))))))

34
lib/lua/test.sh
View File

@@ -460,6 +460,28 @@ cat > "$TMPFILE" << 'EPOCHS'
(epoch 561)
(eval "(lua-eval-ast \"local function sum_to(n) local s = 0 for i = 1, n do s = s + i end return s end return sum_to(10)\")")
;; ── Phase 3: multi-return + unpack ────────────────────────────
(epoch 570)
(eval "(lua-eval-ast \"local a, b = (function() return 1, 2 end)() return a + b\")")
(epoch 571)
(eval "(lua-eval-ast \"local function two() return 10, 20 end local a, b = two() return b - a\")")
(epoch 572)
(eval "(lua-eval-ast \"function swap(a, b) return b, a end local x, y = swap(1, 2) return x * 10 + y\")")
(epoch 573)
(eval "(lua-eval-ast \"local function three() return 1, 2, 3 end local a, b = three() return a * 10 + b\")")
(epoch 574)
(eval "(lua-eval-ast \"local function two() return 1, 2 end local a, b, c = two() if c == nil then return a + b else return 0 end\")")
(epoch 575)
(eval "(lua-eval-ast \"local function two() return 5, 7 end local function outer() return two() end local a, b = outer() return a + b\")")
(epoch 576)
(eval "(lua-eval-ast \"local function two() return 9, 9 end local a, b = two(), 5 return a * 10 + b\")")
(epoch 577)
(eval "(lua-eval-ast \"local function pair() return 4, 5 end local x = pair() return x + 1\")")
(epoch 578)
(eval "(lua-eval-ast \"local function none() return end local a, b = none() if a == nil and b == nil then return 99 else return 0 end\")")
(epoch 579)
(eval "(lua-eval-ast \"local a = 0 local b = 0 local function m() return 7, 11 end a, b = m() return a + b\")")
EPOCHS
OUTPUT=$(timeout 60 "$SX_SERVER" < "$TMPFILE" 2>/dev/null)
@@ -710,6 +732,18 @@ check 551 "twice(+1, 5)" '7'
check 560 "max with if" '7'
check 561 "sum_to(10) with for" '55'
# ── Phase 3: multi-return + unpack ────────────────────────────
check 570 "anon-fn returns 2, unpack" '3'
check 571 "local fn returns 2, unpack" '10'
check 572 "swap via multi-return" '21'
check 573 "extra returns discarded" '12'
check 574 "missing returns nil-padded" '3'
check 575 "tail-return passthrough" '12'
check 576 "non-last call truncated to 1st" '95'
check 577 "single-assign truncates to 1st" '5'
check 578 "empty return → all nil" '99'
check 579 "multi-assign (non-local)" '18'
TOTAL=$((PASS + FAIL))
if [ $FAIL -eq 0 ]; then
echo "ok $PASS/$TOTAL Lua-on-SX tests passed"

112
lib/lua/transpile.sx
View File

@@ -190,9 +190,13 @@
(list
(make-symbol "define")
(make-symbol (first names))
(if (> (len exps) 0) (lua-tx (first exps)) nil)))
(else
(cons (make-symbol "begin") (lua-tx-local-pairs names exps 0)))))))
(if
(> (len exps) 0)
(list (make-symbol "lua-first") (lua-tx (first exps)))
nil)))
((= (len exps) 0)
(cons (make-symbol "begin") (lua-tx-local-pairs names exps 0)))
(else (lua-tx-multi-local names exps))))))
(define
lua-tx-local-pairs
@@ -216,9 +220,12 @@
((lhss (nth node 1)) (rhss (nth node 2)))
(cond
((= (len lhss) 1)
(lua-tx-single-assign (first lhss) (lua-tx (first rhss))))
(else
(cons (make-symbol "begin") (lua-tx-assign-pairs lhss rhss 0)))))))
(lua-tx-single-assign
(first lhss)
(list (make-symbol "lua-first") (lua-tx (first rhss)))))
((= (len rhss) 0)
(cons (make-symbol "begin") (lua-tx-assign-pairs lhss rhss 0)))
(else (lua-tx-multi-assign lhss rhss))))))
(define
lua-tx-assign-pairs
@@ -399,7 +406,10 @@
(cond
((= (len exps) 0) nil)
((= (len exps) 1) (lua-tx (first exps)))
(else (cons (make-symbol "list") (map lua-tx exps)))))))
(else
(list
(make-symbol "lua-pack-return")
(cons (make-symbol "list") (lua-tx-multi-args exps 0))))))))
(define
lua-tx-local-function
@@ -434,3 +444,91 @@
(define
lua-eval-ast
(fn (src) (let ((sx (lua-transpile src))) (eval-expr sx))))
(define
lua-tx-multi-args
(fn
(exps i)
(cond
((>= i (len exps)) (list))
((= i (- (len exps) 1))
(cons (lua-tx (nth exps i)) (lua-tx-multi-args exps (+ i 1))))
(else
(cons
(list (make-symbol "lua-first") (lua-tx (nth exps i)))
(lua-tx-multi-args exps (+ i 1)))))))
(define
lua-tx-multi-rhs
(fn
(exps)
(list
(make-symbol "lua-pack-return")
(cons (make-symbol "list") (lua-tx-multi-args exps 0)))))
(define
lua-tx-multi-local
(fn
(names exps)
(let
((tmp (make-symbol "__rets")))
(cons
(make-symbol "begin")
(append
(lua-tx-multi-local-decls names 0)
(list
(list
(make-symbol "let")
(list (list tmp (lua-tx-multi-rhs exps)))
(cons
(make-symbol "begin")
(lua-tx-multi-local-sets names tmp 0)))))))))
(define
lua-tx-multi-local-decls
(fn
(names i)
(if
(>= i (len names))
(list)
(cons
(list (make-symbol "define") (make-symbol (nth names i)) nil)
(lua-tx-multi-local-decls names (+ i 1))))))
(define
lua-tx-multi-local-sets
(fn
(names tmp i)
(if
(>= i (len names))
(list)
(cons
(list
(make-symbol "set!")
(make-symbol (nth names i))
(list (make-symbol "lua-nth-ret") tmp i))
(lua-tx-multi-local-sets names tmp (+ i 1))))))
(define
lua-tx-multi-assign
(fn
(lhss rhss)
(let
((tmp (make-symbol "__rets")))
(list
(make-symbol "let")
(list (list tmp (lua-tx-multi-rhs rhss)))
(cons (make-symbol "begin") (lua-tx-multi-assign-pairs lhss tmp 0))))))
(define
lua-tx-multi-assign-pairs
(fn
(lhss tmp i)
(if
(>= i (len lhss))
(list)
(cons
(lua-tx-single-assign
(nth lhss i)
(list (make-symbol "lua-nth-ret") tmp i))
(lua-tx-multi-assign-pairs lhss tmp (+ i 1))))))

3
plans/lua-on-sx.md
View File

@@ -52,7 +52,7 @@ Each item: implement → tests → tick box → update progress log.
### Phase 3 — tables + functions + first PUC-Rio slice
- [x] `function` (anon, local, top-level), closures
- [ ] Multi-return: return as list, unpack at call sites
- [x] Multi-return: return as list, unpack at call sites
- [ ] Table constructors (array + hash + computed keys)
- [ ] Raw table access `t.k` / `t[k]` (no metatables yet)
- [ ] Vendor PUC-Rio 5.1.5 suite to `lib/lua/lua-tests/` (just `.lua` files)
@@ -82,6 +82,7 @@ Each item: implement → tests → tick box → update progress log.
_Newest first. Agent appends on every commit._
- 2026-04-24: lua: multi-return — `lua-multi` tagged value, `lua-first`/`lua-nth-ret`/`lua-pack-return` runtime, tail-position spread in return/local/assign. 185 total tests.
- 2026-04-24: lua: phase 3 — functions (anon/local/top-level) + closures verified (lexical capture, mutation-through-closure, recursion, HOFs). 175 total tests.
- 2026-04-24: lua: phase 2 transpile — arithmetic, comparison, short-circuit logical, `..` concat, if/while/repeat/for-num/local/assign. 157 total tests green.
- 2026-04-24: lua: parser (exprs with precedence, all phase-1 statements, funcbody, table ctors, method/chained calls) — 112 total tokenizer+parser tests