Skip to content

Improve List.length performance#1091

Open
dullbananas wants to merge 3 commits intoelm:masterfrom
dullbananas:list-length
Open

Improve List.length performance#1091
dullbananas wants to merge 3 commits intoelm:masterfrom
dullbananas:list-length

Conversation

@dullbananas
Copy link

No description provided.

to show that it always returns at least one list item even if the string is empty
@harrysarson
Copy link
Contributor

Out of interest: do you have a benchmark?

@dullbananas
Copy link
Author

Out of interest: do you have a benchmark?

I made a benchmark here. It tests a list with 50,000 items.

@harrysarson
Copy link
Contributor

Wow, I see a huge improvement. Looks like by removing the F2 wrappers we get a massive performance gain.

image

var $author$project$Main$currentlength = function (list) {
	return A3(
		$elm$core$List$foldl,
		F2(
			function (_v0, i) {
				return i + 1;
			}),
		0,
		list);
};
var $author$project$Main$lengthHelp0 = F2(
	function (list, acc) {
		lengthHelp0:
		while (true) {
			if (!list.b) {
				return acc;
			} else {
				var xs = list.b;
				var $temp$list = xs,
					$temp$acc = acc + 1;
				list = $temp$list;
				acc = $temp$acc;
				continue lengthHelp0;
			}
		}
	});
var $author$project$Main$newlength = function (list) {
	return A2($author$project$Main$lengthHelp0, list, 0);
};

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants