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fix(std): reject "-0" forms in stringToLong (#1582) #1585

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Merged
julien-truffaut merged 1 commit into from
May 14, 2026
Merged

fix(std): reject "-0" forms in stringToLong (#1582) #1585

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4 changes: 3 additions & 1 deletion core/shared/src/main/scala/monocle/std/String.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,10 @@ trait StringOptics extends PlatformSpecificStringOptics {
// we reject cases where String will be an invalid Prism according 2nd Prism law
// * String starts with +
// * String starts with 0 and has multiple digits
// * String starts with -0 (negative zero forms never round-trip)
def inputBreaksPrismLaws(input: String): Boolean =
s.isEmpty || s.startsWith("+") || (s.startsWith("0") && s.length > 1)
s.isEmpty || s.startsWith("+") || (s.startsWith("0") && s.length > 1) ||
(s.length > 1 && s.charAt(0) == '-' && s.charAt(1) == '0')

if (inputBreaksPrismLaws(s)) None
else
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13 changes: 13 additions & 0 deletions test/shared/src/test/scala/monocle/std/StringsSpec.scala
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Expand Up @@ -25,4 +25,17 @@ class StringsSpec extends MonocleSuite {
// checkAll("String to URI", PrismTests(stringToURI))

checkAll("plated String", TraversalTests(plate[String]))

// see #1582: "-0" et al. parsed to 0L but reverseGet round-tripped to "0"
test("stringToLong rejects negative-zero forms") {
assertEquals(stringToLong.getOption("-0"), None)
assertEquals(stringToLong.getOption("-00"), None)
assertEquals(stringToLong.getOption("-01"), None)
}

test("stringToLong still accepts ordinary negatives and zero") {
assertEquals(stringToLong.getOption("0"), Some(0L))
assertEquals(stringToLong.getOption("-1"), Some(-1L))
assertEquals(stringToLong.getOption("-10"), Some(-10L))
}
}
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