Proposal: https://gist.github.com/karwa/273db66cd8a5fe2c388ccc7de9c4cf31
<https://gist.github.com/karwa/273db66cd8a5fe2c388ccc7de9c4cf31>
Introduction, Motivation
The standard library lacks equivalents to the floor() and ceil() functions
found in the standard libraries of most other languages. Currently, we need to
import Darwin or Glibc in order to access the C standard library versions.
They are essential for many algorithms, and adding them would allow more basic
algorithms to be written platform-independently (or at least without #if (os)
flags at the top).
<https://gist.github.com/karwa/273db66cd8a5fe2c388ccc7de9c4cf31#proposed-solution>Proposed
Solution
Add floor and ceiling functions (and mutating variants) to FloatingPoint
protocol FloatingPoint {
...
/// Returns the largest integral value not greater than `self`
func floor() -> Self
/// Mutating form of `floor`
mutating func formFloor()
/// Returns the smallest integral value not less than `self`
func ceiling() -> Self
/// Mutating form of `ceiling`
mutating func formCeiling()
}
<https://gist.github.com/karwa/273db66cd8a5fe2c388ccc7de9c4cf31#impact-on-existing-code>Impact
on existing code
This change is additive, although we may consider suppressing the imported,
global-level C functions and automatically migrating them to instance method
calls.
<https://gist.github.com/karwa/273db66cd8a5fe2c388ccc7de9c4cf31#alternatives-considered>Alternatives
considered
floor() and ceil(), exactly like C. ceiling() is more descriptive and is a
mathematical term of art <http://mathworld.wolfram.com/CeilingFunction.html>.
nextIntegralUp() and nextIntegralDown() are more descriptive still, but
possibly misleading as (4.0).nextIntegralUp() == 4.0_______________________________________________
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