tallyman

tallyman 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

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

Features

• no_std for embedded use.
• 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.

Supported Tally Methods

Status¹	Tally Method	Supported Variants	Performance²	Notes
✓	Plurality		100 million v/s	First Past the Post (FPTP)
⚠	Score
⚠	Approval
⚠	STV	Newland-Britton, Meek, Warren	3 million v/s	Single Transferable Vote
	CPO-STV
	Instant Runoff
	Contingent
⚠	Condorcet		2 million v/s
	Copeland
	Schulze	Winning, Margin, Ratio
	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

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