gno.land/p/moul/x/daily/rle/v0

Run-length encoding — Encode, Decode, Ratio, MaxLen.

Runs of a repeated byte collapse to <count><char>, counts in decimal: "aaabbc" → "3a2b1c".

1import "gno.land/p/moul/x/daily/rle/v0"
2
3rle.Encode("aaabbc")   // "3a2b1c", nil
4rle.Decode("3a2b1c")   // "aaabbc", nil
5rle.Ratio("abcdef", "1a1b1c1d1e1f")  // 200 — bigger than the input!

Every run carries a count, including runs of one. A uniform grammar is cheaper to decode and impossible to get subtly wrong, at the cost of expanding data that has no runs. That trade is deliberate and visible: Ratio returns over 100 when the "compression" grew the data, because RLE only wins on runny input and pretending otherwise would be dishonest.

Digits are rejected by Encode — in the output they would be indistinguishable from a run count, so a round-trip would silently return the wrong string. Better to refuse.

Decode bounds the expanded size too, not just its input: "999999x" is seven bytes that would otherwise become a megabyte.

Live demo: r/moul/x/daily/rledemo · render it at /r/moul/x/daily/rledemo/v0.

Part of moul/gno-contracts — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage.

🧪 Highly experimental — potentially vibe-coded. Not audited; may break, change, or be removed at any time. Do not use with anything of value. Full disclaimer: DISCLAIMER.