Clarify the documentation of SignedNumeric.

stephentyrone · stephentyrone · commit ce122dbb8106 · 2021-08-04T23:03:33.000-04:00
Previously we said that a type conforming to SignedNumeric allows positive and negative values, but that's nonsense. A type conforms to signed numeric if it has a negate() operation; it doesn't even have to have a notion of positive or negative values (for examples, see complex numbers, quaternions, integers mod n, etc).
diff --git a/stdlib/public/core/Integers.swift b/stdlib/public/core/Integers.swift
@@ -258,7 +258,7 @@ public protocol Numeric: AdditiveArithmetic, ExpressibleByIntegerLiteral {
   static func *=(lhs: inout Self, rhs: Self)
 }
 
-/// A type that can represent both positive and negative values.
+/// A numeric type with a negation operation.
 ///
 /// The `SignedNumeric` protocol extends the operations defined by the
 /// `Numeric` protocol to include a value's additive inverse.

Original file line number	Diff line number	Diff line change
`@@ -258,7 +258,7 @@ public protocol Numeric: AdditiveArithmetic, ExpressibleByIntegerLiteral {`
`258`	`258`	`static func *=(lhs: inout Self, rhs: Self)`
`259`	`259`	`}`
`260`	`260`
`261`		`-/// A type that can represent both positive and negative values.`
	`261`	`+/// A numeric type with a negation operation.`
`262`	`262`	`///`
`263`	`263`	/// The `SignedNumeric` protocol extends the operations defined by the
`264`	`264`	/// `Numeric` protocol to include a value's additive inverse.