From 253d64b1e708ec19a58f50fd78d64e9ea44d4033 Mon Sep 17 00:00:00 2001 From: Yogthos Date: Sat, 27 Jun 2026 22:49:42 -0400 Subject: [PATCH] unchecked-* on a ratio (or any non-long) shouldn't wrap to 64-bit jolt-unc{add,sub,mul,inc,dec,neg}2 wrapped every non-flonum result to a signed 64-bit integer, so (unchecked-add 2/3 2/3) truncated to 1 instead of 4/3. Under *unchecked-math* the analyzer rewrites +/-/* to unchecked-*, so any ratio arithmetic in such a file silently floored. Clojure's unchecked-add falls back to regular arithmetic for non-primitives; only long math wraps. Wrap iff both operands are exact integers. Shaken out by test.check's gen/ratio monoid property (the + and 0 monoid held for small-integers but failed for ratios). --- host/chez/seq.ss | 24 ++++++++++++++---------- test/chez/corpus.edn | 5 +++++ 2 files changed, 19 insertions(+), 10 deletions(-) diff --git a/host/chez/seq.ss b/host/chez/seq.ss index 96e3899..58ca46b 100644 --- a/host/chez/seq.ss +++ b/host/chez/seq.ss @@ -165,16 +165,20 @@ (define (jolt-wrap64 x) (let ((m (bitwise-and (if (and (number? x) (exact? x) (integer? x)) x (exact (floor x))) unc-mask64))) (if (>= m unc-2^63) (- m unc-2^64) m))) -;; unchecked-* only WRAP integer (long) math; on a flonum operand they are an -;; ordinary float op, since *unchecked-math* never wraps doubles — Clojure: -;; (unchecked-multiply 1.5 2.0) => 3.0, not a truncated long. (test.check's -;; rand-double is (* double-unit shifted) under *unchecked-math*.) -(define (jolt-uncadd2 a b) (if (or (flonum? a) (flonum? b)) (+ a b) (jolt-wrap64 (+ a b)))) -(define (jolt-uncsub2 a b) (if (or (flonum? a) (flonum? b)) (- a b) (jolt-wrap64 (- a b)))) -(define (jolt-uncmul2 a b) (if (or (flonum? a) (flonum? b)) (* a b) (jolt-wrap64 (* a b)))) -(define (jolt-uncinc x) (if (flonum? x) (+ x 1.0) (jolt-wrap64 (+ x 1)))) -(define (jolt-uncdec x) (if (flonum? x) (- x 1.0) (jolt-wrap64 (- x 1)))) -(define (jolt-uncneg x) (if (flonum? x) (- x) (jolt-wrap64 (- x)))) +;; unchecked-* only WRAP integer (long) math; on a flonum OR ratio operand they +;; are an ordinary numeric op, since *unchecked-math* never wraps a non-long — +;; Clojure's unchecked-add falls back to regular arithmetic for non-primitives: +;; (unchecked-multiply 1.5 2.0) => 3.0, (unchecked-add 2/3 2/3) => 4/3, not a +;; truncated long. (test.check's rand-double is (* double-unit shifted), and +;; gen/ratio sums ratios, both under *unchecked-math*.) Wrap iff both are exact +;; integers. +(define (unc-int? x) (and (exact? x) (integer? x))) +(define (jolt-uncadd2 a b) (if (and (unc-int? a) (unc-int? b)) (jolt-wrap64 (+ a b)) (+ a b))) +(define (jolt-uncsub2 a b) (if (and (unc-int? a) (unc-int? b)) (jolt-wrap64 (- a b)) (- a b))) +(define (jolt-uncmul2 a b) (if (and (unc-int? a) (unc-int? b)) (jolt-wrap64 (* a b)) (* a b))) +(define (jolt-uncinc x) (if (unc-int? x) (jolt-wrap64 (+ x 1)) (+ x 1))) +(define (jolt-uncdec x) (if (unc-int? x) (jolt-wrap64 (- x 1)) (- x 1))) +(define (jolt-uncneg x) (if (unc-int? x) (jolt-wrap64 (- x)) (- x))) (define (jolt-unchecked-add . xs) (if (null? xs) 0 (fold-left jolt-uncadd2 (car xs) (cdr xs)))) (define (jolt-unchecked-mul . xs) (if (null? xs) 1 (fold-left jolt-uncmul2 (car xs) (cdr xs)))) (define (jolt-unchecked-sub . xs) diff --git a/test/chez/corpus.edn b/test/chez/corpus.edn index c1524b6..0616755 100644 --- a/test/chez/corpus.edn +++ b/test/chez/corpus.edn @@ -1484,6 +1484,11 @@ {:suite "numbers / promoting & unchecked aliases" :label "unchecked-remainder-int negative" :expected "-1" :actual "(unchecked-remainder-int -7 2)"} {:suite "numbers / promoting & unchecked aliases" :label "unchecked-int truncates" :expected "3" :actual "(unchecked-int 3.7)"} {:suite "numbers / promoting & unchecked aliases" :label "unchecked-int negative" :expected "-3" :actual "(unchecked-int -3.7)"} + {:suite "numbers / promoting & unchecked aliases" :label "unchecked-add on ratios does not wrap to long" :expected "4/3" :actual "(unchecked-add 2/3 2/3)"} + {:suite "numbers / promoting & unchecked aliases" :label "unchecked-multiply ratio by int" :expected "4/3" :actual "(unchecked-multiply 2/3 2)"} + {:suite "numbers / promoting & unchecked aliases" :label "unchecked-negate ratio" :expected "-2/3" :actual "(unchecked-negate 2/3)"} + {:suite "numbers / promoting & unchecked aliases" :label "unchecked-add ratios summing to zero" :expected "0" :actual "(unchecked-add 1/2 -1/2)"} + {:suite "numbers / promoting & unchecked aliases" :label "unchecked-inc ratio" :expected "3/2" :actual "(unchecked-inc 1/2)"} {:suite "numbers / promoting & unchecked aliases" :label "unchecked-long" :expected "3" :actual "(unchecked-long 3.7)"} {:suite "numbers / promoting & unchecked aliases" :label "int? on integer" :expected "true" :actual "(int? 5)"} {:suite "numbers / promoting & unchecked aliases" :label "int? on double" :expected "false" :actual "(int? 5.5)"}