func Caesar
Caesar generalizes ROT13 to an arbitrary shift. Negative and large shifts are normalized into [0,26). Only ASCII letters move; anything else passes through unchanged. Caesar(s, 13) is exactly Rot13(s).
v0 source pure
Package rot13 ports Go's classic ROT13 example — the one used to teach strings.Map and io.Reader in the standard libr...
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gno.land/p/moul/x/daily/rot13/v0
ROT13 / Caesar letter-rotation cipher — Rot13, Caesar.
Pure strings.Map logic over ASCII letters; everything else passes through
untouched. ROT13 shifts each letter 13 places and, since the alphabet has 26
letters, is its own inverse. Caesar generalizes it to any shift (negative and
large shifts normalized into [0,26)). Ports Go's classic ROT13 teaching
example.
1import "gno.land/p/moul/x/daily/rot13/v0"
2
3s := rot13.Rot13("Hello, Gno!") // "Uryyb, Tab!"
4d := rot13.Rot13(s) // "Hello, Gno!" (own inverse)
5c := rot13.Caesar("attack", 3) // "dwwdfn"
Live demo: r/moul/x/daily/rot13demo
· render it at /r/moul/x/daily/rot13demo/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.
Package rot13 ports Go's classic ROT13 example — the one used to teach strings.Map and io.Reader in the standard library docs — to gno as a reusable pure package. The core is a pure letter-rotation cipher over ASCII: ROT13 shifts each letter 13 places, which (since the alphabet has 26 letters) makes ROT13 its own inverse. Caesar generalizes it to any shift.
Everything here is pure strings/unicode logic: no state, no randomness, no clock.
A live demo of this package is at r/moul/x/daily/rot13demo(/r/moul/x/daily/rot13demo/v0).
2
func Rot13
Rot13 applies the ROT13 substitution cipher, rotating ASCII letters by 13 and leaving every other byte untouched. Because 13 is half of 26, Rot13(Rot13(s)) == s — the cipher is its own inverse. This mirrors the canonical strings.Map example from the Go docs.
1
- strings stdlib