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ocaml: phase 2 for/while loops (+5 tests, 194 total)
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Parser: for i = lo to|downto hi do body done, while cond do body done.
AST: (:for NAME LO HI :ascend|:descend BODY) and (:while COND BODY).
Eval re-binds the loop var per iteration; both forms evaluate to unit.
This commit is contained in:
giles
2026-05-08 08:11:13 +00:00
parent a11f3c33b6
commit 9b8b0b4325
4 changed files with 98 additions and 1 deletions
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45
lib/ocaml/eval.sx
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@@ -300,6 +300,51 @@
(fn-val arg-val))))))
((= tag "match")
(ocaml-match-eval (nth ast 1) (nth ast 2) env))
((= tag "for")
;; (:for NAME LO HI DIR BODY) — DIR is "ascend" or "descend".
(let ((name (nth ast 1))
(lo (ocaml-eval (nth ast 2) env))
(hi (ocaml-eval (nth ast 3) env))
(dir (nth ast 4))
(body (nth ast 5)))
(begin
(cond
((= dir "ascend")
(let ((i lo))
(begin
(define loop
(fn ()
(when (<= i hi)
(begin
(ocaml-eval body
(ocaml-env-extend env name i))
(set! i (+ i 1))
(loop)))))
(loop))))
((= dir "descend")
(let ((i lo))
(begin
(define loop
(fn ()
(when (>= i hi)
(begin
(ocaml-eval body
(ocaml-env-extend env name i))
(set! i (- i 1))
(loop)))))
(loop)))))
nil)))
((= tag "while")
(let ((cond-ast (nth ast 1)) (body (nth ast 2)))
(begin
(define loop
(fn ()
(when (ocaml-eval cond-ast env)
(begin
(ocaml-eval body env)
(loop)))))
(loop)
nil)))
((= tag "let")
(let ((name (nth ast 1)) (params (nth ast 2))
(rhs (nth ast 3)) (body (nth ast 4)))