Bug 8573 – A simpler Phobos function that returns the index of the mix or max item

countUntil returns a signed value with the position, or -1 if not found: import std.algorithm: countUntil; void main() { assert(countUntil("hello world", 'r') == 8); } But to find the index of the minimum item things become more complex and more bug-prone: import std.algorithm: minPos; import std.range: walkLength; void main() { immutable s = "hello world"; immutable sizediff_t mpos = s.walkLength() - minPos(s).walkLength(); assert(mpos == 5); } I have typed mpos "sizediff_t" to avoid troubles caused by a unsigned position value. In Python taking the sum() of an empty list (array) returns 0, while searching for min/max in an empty list causes a ValueError exception to be thrown: >>> a = [] >>> sum(a) 0 >>> min(a) Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: min() arg is an empty sequence In D here mpos is 0: import std.algorithm: minPos; import std.range: walkLength; void main() { immutable s = ""; immutable sizediff_t mpos = s.walkLength() - minPos(s).walkLength(); assert(mpos == 0); } So in Phobos I'd like a simple to use function that returns the sizediff_t index of the min item (and when the input is empty, it returns -1 or throws an exception).

Alternatively we could use std.range.enumerate with minPos. minPos could take a unary map function like minElement does: auto index = range.enumerate.minPos!`a.value`.front.value;

Oops, should be .front.index at the end.

Commits pushed to master at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/d2c7d3761b73405ee39da3fd7fe5030dee35a39e Issue 8573 - A simpler Phobos function that returns the index of the mix or max item Issue 8573 - A simpler Phobos function that returns the index of the mix or max item added some review fixes fixed an issue with a mutable variable Applied review feedback Renamed functions to minIndex and maxIndex + used sizediff_t for return value type Updated function so that it works optimally even for lazy ranges and algorithms Reverted to having only copyable elements in ranges Added more unittests; implemented an array path; fixed documentation Squashed commits https://github.com/dlang/phobos/commit/f3a840144a156fce5efee82ca13152c2ac1ef1c3 Merge pull request #4921 from RazvanN7/Issue_8573 Issue 8573 - A simpler Phobos function that returns the index of the …

Commits pushed to stable at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/d2c7d3761b73405ee39da3fd7fe5030dee35a39e Issue 8573 - A simpler Phobos function that returns the index of the mix or max item https://github.com/dlang/phobos/commit/f3a840144a156fce5efee82ca13152c2ac1ef1c3 Merge pull request #4921 from RazvanN7/Issue_8573

Commits pushed to newCTFE at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/d2c7d3761b73405ee39da3fd7fe5030dee35a39e Issue 8573 - A simpler Phobos function that returns the index of the mix or max item https://github.com/dlang/phobos/commit/f3a840144a156fce5efee82ca13152c2ac1ef1c3 Merge pull request #4921 from RazvanN7/Issue_8573

Implemented as stated in comments.