#371 in Science

25 downloads per month

MIT/Apache

185KB
2.5K SLoC

tallystick

tallystick is a work-in-progress rust library for tallying votes.

Current state is very unstable. It is not currently recommended for use. See checkboxes below for a list of features that are complete.

Goals

Ergonomic - Easy to use.
Fast - Be the fastest general-purpose vote tallying library in the world.
Secure - Have no undefined behavior.
Complete - Support all well-known voting methods.
Deterministic - Running the same tally twice should never produce different results.
Generic - Generic over both candidate and count types.

wasm support for use in the browser, or in blockchain smart contracts.
rational support for perfectly-precise tallies by using rational fractions instead of floats.
fixed_point support for decimal fixed-point tallies, required by some statutes.
ffi support for calling from other programming languages.
alloc support for embedded and other applications where there is an allocator, but no standard library.

Status¹	Tally Method	Supported Variants	Performance²	Notes
✓	Plurality		120 million v/s	First Past the Post (FPTP)
✓	Score		3 million v/s
✓	Approval		4 million v/s
⚠	STV	Newland-Britton, Meek, Warren	3 million v/s	Single Transferable Vote
	CPO-STV
⚠	Instant Runoff
	Contingent
	Supplementary
✓	Condorcet		2 million v/s
	Copeland
✓	Schulze	Winning, Margin, Ratio	2 million v/s
	Schulze STV
	Kemeny–Young
	Minimax
✓	Borda	Classic, Dowdall, Modified	3 million v/s
	Borda - Nanson	Classic, Dowdall, Modified
	Borda - Baldwin	Classic, Dowdall, Modified
	Dodgson	Quick, Tideman
	Ranked pairs	Margin, Winning
	STAR
	Majority judgment
	D'Hondt	Sainte-Laguë, Huntington-Hill, Quota

✓ means done, ⚠ means in-progress, blank means not started but support is planned.
Single threaded performance measured in votes tallied per second. Benchmarked on a 2017 Macbook Pro.

~2.8–4MB
~64K SLoC