Appendix C, Yon, for those coming from elsewhere

Calibrated comparisons. Where a rival is more mature, this page says so.

From Unison. Unison content-addresses code, definitions are hashes, renames are free. Yon content-addresses runtime values: allocation itself deduplicates, and deep equality is one comparison (chapter 13). The ideas rhyme; the object differs. Unison's codebase manager has no Yon equivalent; Yon's O(1) value equality has no Unison equivalent.

From Erlang/Elixir. Erlang is the gold standard of process isolation, and its messaging (arbitrary terms, distribution across machines, supervision trees) is far richer than Yon's numeric wire. Yon's trade is deliberate: kernel processes instead of a VM, a wire the type checker polices (a string in a cross-Space signature does not compile), and handles that are meaningless in the wrong process rather than merely forbidden. Choose Erlang for distributed systems today; Yon's bet is that a narrower door makes a stronger wall.

From Haskell. Typeclass laws in Haskell are documentation; Yon's law declarations are checked, the algebra verifier rejects a false commutative at compile time (chapter 6). The price: a closed catalog of algebras, not arbitrary laws. Where Haskell says "trust the instance", Yon says "prove it or don't claim it", for the algebras it knows.

From Lean/Idris/Agda. Proof assistants verify arbitrary laws, with your labor. Yon sits at a different point: automatic, bounded verification, plus something proof assistants don't do: verify hands the verified structure back as a runnable object (chapter 6), whose reachability view carries the witness for each reachable value (chapter 12). Yon's HoTT layer (chapter 9) is a fragment of theirs; its topos vocabulary as compiled syntax has no equivalent there.

From Rust. Rust earns memory safety through ownership and lifetimes, analysis of who may touch what when. Yon dissolves the question instead of answering it: values are immutable content with no identity, so there is nothing to race on and nothing to alias; the one identity (cells) is explicit and process-local. Rust's model costs annotations and buys zero-overhead mutation; Yon's costs mutation-by-default and buys a model with no aliasing to reason about. Rust's ecosystem and performance story are vastly more mature; that is not in dispute.

What has no counterpart anywhere, stated once and narrowly: allocation-as-deduplication with O(1) deep equality as a language guarantee; orbit canonicalization in the Arena (equality up to a symmetry group as storage semantics); verify returning verified algebras as runnable objects; trit-valued integers with per-bit certainty; error-correcting storage in the standard library; topos constructs as compiled primitives rather than library encodings.