a streaming array language

A K-inspired array language with a runtime written in Rust. Evaluation is streaming and chunked — long computations advance in small fixed-size chunks, so Ctrl-C reaches the running kernel within one chunk-time (roughly 6–60 µs for arithmetic kernels) and the REPL stays responsive even mid-fold. The runtime is single-threaded on a tokio current-thread executor; the REPL is built on reedline.

Early. The current vertical slice covers parser, tree-walking eval, atom and typed-vector pretty-printing, the primitives + − × ÷, the +/ (sum) adverb, the monadic ! (til / iota), Ctrl-C cancellation, history persistence, and K-style system commands. Not yet: dictionaries, tables, IO, user-defined verbs, multi-threaded execution.

keyten/        runtime library  — object layout, kernels, parser, eval
keyten-cli/    binary `keyten`  — reedline REPL, formatter, banner, sys-cmds

The library has no tokio runtime dependency by default; the CLI owns the runtime. Sync entry points exist alongside the *_async ones for embedders that don't want tokio.

Rust 1.80+ is required (edition 2021).

# launch the REPL
cargo run -p keyten-cli --release

# library tests + CLI tests
cargo test --workspace

# minimal embedding example
cargo run -p keyten --example calc

𝕜 1 + 2
3

𝕜 +/!1000000
499999500000

𝕜 \t +/!10000000
4999999950000  (12.4 ms)

𝕜 x: !5
0 1 2 3 4

𝕜 \v
x

𝕜 \h
  \t expr   time evaluation of expr
  \v        list bound variables
  \h \?     help
  \\        quit

𝕜 \\

Ctrl-C during a long fold cancels the kernel without exiting the REPL.

Dual-licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this work, as defined in the Apache-2.0 license, shall be dual-licensed as above, without any additional terms or conditions.