{
"$type": "site.standard.document",
"bskyPostRef": {
"cid": "bafyreiddrwhe4bewwlica7i45zxkzguvr5d7km4s4ccywis6tdgo2wvoue",
"commit": {
"cid": "bafyreieu4lycjvo4nj3w7qba7jtqxjcdsk3pel7ihxcec6st76bbnoketu",
"rev": "3mpusady4gb2l"
},
"uri": "at://did:plc:ba4ljetiaeiu5vrpfhymga7a/app.bsky.feed.post/3mpusadwebk2o",
"validationStatus": "valid"
},
"content": {
"$type": "pub.leaflet.content",
"pages": [
{
"$type": "pub.leaflet.pages.linearDocument",
"blocks": [
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"facets": [
{
"features": [
{
"$type": "pub.leaflet.richtext.facet#bold"
}
],
"index": {
"byteEnd": 48,
"byteStart": 30
}
},
{
"features": [
{
"$type": "pub.leaflet.richtext.facet#bold"
}
],
"index": {
"byteEnd": 91,
"byteStart": 78
}
}
],
"plaintext": "The cleanest way to implement public regex feeds in Nostr is to treat them as saved queries, not as a new Nostr protocol feature."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "There are two common approaches."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "1. Client-side filtering (recommended)"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "A user subscribes to a normal Nostr feed, and the client filters events locally using a regex."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "For example:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "Feed: Rust Jobs\n\nRegex:\n(?i)\\b(rust|leptos|tokio|wasm)\\b"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "The relay sends all text notes, and the client only displays matching events."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Advantages:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.unorderedList",
"children": [
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "No relay modifications."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Works on every relay."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Privacy (relay doesn't know your regex)."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Compatible with existing Nostr."
}
}
]
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Disadvantages:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.unorderedList",
"children": [
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Downloads many unnecessary events."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Doesn't scale for large feeds."
}
}
]
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Rust example:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "rust",
"plaintext": "use regex::Regex;\n\nlet regex = Regex::new(r\"(?i)\\brust\\b\").unwrap();\n\nif regex.is_match(&event.content) {\n println!(\"Matched!\");\n}"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "2. Relay-side filtering (better for public feeds)"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Imagine a relay dedicated to public feeds."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Users create feeds like:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "rust\nai\nindia\nbitcoin"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Each feed stores"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "Feed ID\nRegex\nOwner\nDescription"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "When someone subscribes:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "REQ\n[\n \"subid\",\n {\n \"kinds\":[1],\n \"#feed\":[\"rust\"]\n }\n]"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "The relay translates"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "feed \"rust\"\n\n↓\n\n(?i)\\b(rust|cargo|tokio|leptos)\\b"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "and only streams matching events."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "This greatly reduces bandwidth."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Representing feeds in Nostr"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "You could publish feeds as a custom event."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Example:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "json",
"plaintext": "{\n \"kind\": 30078,\n \"content\": \"\",\n \"tags\": [\n [\"d\", \"rust\"],\n [\"title\", \"Rust Developers\"],\n [\"regex\", \"(?i)\\\\b(rust|cargo|tokio|leptos)\\\\b\"]\n ]\n}"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Clients discover these feed definitions and allow users to subscribe."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Relay implementation (Rust)"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"facets": [
{
"features": [
{
"$type": "pub.leaflet.richtext.facet#code"
}
],
"index": {
"byteEnd": 15,
"byteStart": 10
}
}
],
"plaintext": "Using the regex crate:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "rust",
"plaintext": "use regex::Regex;\n\nstruct Feed {\n id: String,\n regex: Regex,\n}\n\nfn matches(feed: &Feed, content: &str) -> bool {\n feed.regex.is_match(content)\n}"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "When an event arrives:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "rust",
"plaintext": "for feed in feeds {\n if feed.regex.is_match(&event.content) {\n send_to_subscribers(feed.id.clone(), event.clone());\n }\n}"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Making it efficient"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Compiling regex for every event is slow."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Instead:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "rust",
"plaintext": "struct Feed {\n id: String,\n regex: Regex,\n}"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Compile once when the feed is created."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Then reuse:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "rust",
"plaintext": "feed.regex.is_match(&event.content)"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Scaling to thousands of feeds"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"facets": [
{
"features": [
{
"$type": "pub.leaflet.richtext.facet#bold"
}
],
"index": {
"byteEnd": 62,
"byteStart": 44
}
}
],
"plaintext": "Checking every regex against every event is O(events × feeds), which becomes expensive."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "A better pipeline is:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "Incoming Event\n │\n ▼\nTokenize words\n │\n ▼\nCandidate feed lookup\n │\n ▼\nRun regex only on candidate feeds\n │\n ▼\nSend to subscribers"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "For example:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.code",
"language": "plaintext",
"plaintext": "Event:\n\n\"I love Rust and Tokio.\"\n\nTokens:\n\nrust\ntokio\nlove\n\n↓\n\nCandidate feeds:\n\nRust\nAsync\nProgramming\n\n↓\n\nRun regex on only those feeds."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "An inverted index (keyword → feed IDs) drastically reduces the number of regex evaluations."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.horizontalRule"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Even faster alternative"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "If most feeds are keyword-based rather than requiring full regex power, use the aho-corasick crate. It matches thousands of patterns simultaneously in a single pass and is significantly faster than evaluating many independent regexes. You can reserve regex evaluation only for feeds that genuinely need complex expressions."
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.header",
"level": 2,
"plaintext": "Recommendation"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "For a public, community-driven feed system:"
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.unorderedList",
"children": [
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Store feed definitions as Nostr events (e.g., a custom parameterized replaceable kind)."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Relays maintain an in-memory cache of compiled regexes."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Users subscribe to feed IDs rather than sending raw regexes."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Use an inverted keyword index or Aho-Corasick prefilter before regex matching to scale efficiently."
}
},
{
"$type": "pub.leaflet.blocks.unorderedList#listItem",
"content": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "Keep client-side regex filtering as a fallback for relays that don't support server-side public feeds."
}
}
]
}
},
{
"$type": "pub.leaflet.pages.linearDocument#block",
"block": {
"$type": "pub.leaflet.blocks.text",
"plaintext": "This design is bandwidth-efficient, scales much better than naive regex matching, and remains compatible with the existing Nostr event model while allowing anyone to publish and share reusable public feeds."
}
}
],
"id": "019f30a5-bf50-7449-93bd-ced50320a9ee"
}
]
},
"description": "",
"path": "/3mpusa2gnjk25",
"publishedAt": "2026-07-05T05:01:11.611Z",
"site": "at://did:plc:ba4ljetiaeiu5vrpfhymga7a/site.standard.publication/3mpsfeljbgs2t",
"tags": [
"regex",
"nostr"
],
"title": "Regex public feeds in nostr"
}