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Arguments · 9

1. #1luhndemo
2. #2README.md
3. #3# Luhn Checksum > ⚠️ **Experimental — generated with no human supervision** by the daily MCP pipeline to exercise gno tooling. Not audited. See [r/moul/x/daily](https://github.com/moul/gno-contracts/blob/main/r/moul/x/daily/README.md). --- Put a number in the path and the realm tells you whether its Luhn check digit is right — and if not, what it should have been. Demo of the [`p/moul/x/daily/luhn`](https://github.com/moul/gno-contracts/tree/main/p/moul/x/daily/luhn/v0) library — validation, the check digit and the separator handling all come from the package; this realm holds no checksum logic of its own. Read-only and stateless, so `Render` is fully deterministic. ``` /r/moul/x/daily/luhndemo/v0 → usage + worked samples /r/moul/x/daily/luhndemo/v0:79927398713 → valid /r/moul/x/daily/luhndemo/v0:79927398710 → invalid, suggests check digit 3 /r/moul/x/daily/luhndemo/v0:4539-1488-0343-6467 → separators are ignored ``` The samples on the root page are picked to show the two error classes Luhn actually catches: a wrong digit, and two adjacent digits swapped. Built for gno 0.9. <!-- BEGIN GNOCONTRACTS FOOTER (generated by `make readmes`; do not edit below) --> --- Part of **[moul/gno-contracts](https://github.com/moul/gno-contracts)** — moul's versioned gno.land contracts. See the repository for the full catalog, build/test tooling, and usage. **Dependency graph:**  > 🧪 **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](https://github.com/moul/gno-contracts/blob/main/DISCLAIMER.md). <!-- END GNOCONTRACTS FOOTER -->
4. #4gnomod.toml
5. #5module = "gno.land/r/moul/x/daily/luhndemo/v0" gno = "0.9"
6. #6luhndemo.gno
7. #7// Package luhndemo is a small gnoweb demo of the Luhn mod-10 checksum provided // by the [p/moul/x/daily/luhn](/p/moul/x/daily/luhn/v0) library: put a number // in the path and it tells you whether the check digit is right, and what it // should have been. // // It contains no checksum logic of its own — validation, the check digit and // the separator handling all come from the library. Read-only and stateless, so // Render is fully deterministic. package luhndemo import ( "strconv" "strings" "gno.land/p/moul/x/daily/luhn/v0" ) // samples are shown on the root page: a valid number, a typo'd one, and a // transposition — the two error classes Luhn is designed to catch. var samples = []struct { number string note string }{ {"79927398713", "the textbook example"}, {"79927398710", "same number, wrong check digit"}, {"4539148803436467", "a test card number"}, {"4539148803436647", "same card, two digits swapped"}, } // Render renders the checker for gnoweb. // // Render("") / Render("/") -> usage + worked samples // Render("/<digits>") -> verdict for that number func Render(path string) string { in := parseInput(path) var b strings.Builder b.WriteString("# Luhn Checksum\n\n") b.WriteString("The mod-10 check behind card numbers and IMEIs, demoing the ") b.WriteString("[`p/moul/x/daily/luhn`](/p/moul/x/daily/luhn/v0) library.\n\n") if in == "" { b.WriteString("Append a number to the path to check it — spaces and hyphens are ignored.\n\n") b.WriteString("## Samples\n\n") b.WriteString("| number | valid? | note |\n|---|---|---|\n") for _, s := range samples { b.WriteString("| `") b.WriteString(s.number) b.WriteString("` | ") b.WriteString(verdict(luhn.Valid(s.number))) b.WriteString(" | ") b.WriteString(s.note) b.WriteString(" |\n") } b.WriteString("\n> Luhn is a **typo check, not a security check**: it catches every ") b.WriteString("single-digit error and nearly every swap of adjacent digits, but ") b.WriteString("anyone can compute a valid number. Never authorize anything with it.\n") return b.String() } b.WriteString("## `") b.WriteString(in) b.WriteString("`\n\n") if luhn.Valid(in) { b.WriteString("**Valid** — the check digit matches.\n") return b.String() } b.WriteString("**Not valid.**\n\n") // Offer the fix: treat everything but the last digit as the payload. if payload, ok := trimLast(in); ok { if d, ok2 := luhn.CheckDigit(payload); ok2 { b.WriteString("Keeping the leading digits, the check digit should be **") b.WriteString(strconv.Itoa(d)) b.WriteString("**") if fixed, ok3 := luhn.Append(payload); ok3 { b.WriteString(" — i.e. `") b.WriteString(fixed) b.WriteString("`") } b.WriteString(".\n") return b.String() } } b.WriteString("It has no usable digits to check.\n") return b.String() } // parseInput extracts the first path segment. func parseInput(path string) string { s := strings.TrimSpace(path) s = strings.TrimPrefix(s, "/") if i := strings.IndexByte(s, '/'); i >= 0 { s = s[:i] } return s } // trimLast drops the final digit, ignoring separators, to recover the payload. func trimLast(s string) (string, bool) { for i := len(s) - 1; i >= 0; i-- { if s[i] >= '0' && s[i] <= '9' { return s[:i], true } } return "", false } func verdict(ok bool) string { if ok { return "✅ valid" } return "❌ invalid" }
8. #8/gno.MemPackageType
9. #9 MPUserProd