[[!meta date="2026-09-22 16:22"]]
[[!tag nix nixos libnix nixpkgs]]
[[!series libnix]]
[[!summary libnix impact study for rust eco system and beyond]]

[[!img media/nixos-lores.png class="noFancy" style="float: right"]]

# motivation

**libnix can be added to any package manager (PM) so consider this also a direction PMs will be heading in general with libnix.**

this post looks into the cargo+libnix impact, i.e. using the prototype discussed in the previous post [cargo-libnix](https://lastlog.de/blog/libnix_cargo-libnix_release.html), and we use:

* nixpkgs revision [1c3d5a53f03f2eb5677f6f3b34f0ef31261ba485](https://github.com/NixOS/nixpkgs/commit/1c3d5a53f03f2eb5677f6f3b34f0ef31261ba485), from **Sat Dec 13 13:17:29 2025 +0000**
* see full details here: [nixpkgs-datamining](https://github.com/qknight/nixpkgs-datamining)

# rust & crates.io

a rust project usually uses crates.io dependencies like serde, syn and similar. these can be visualized with [cargo-depgraph](https://sr.ht/~jplatte/cargo-depgraph/):

[[!img posts/libnix/cargo-depgraph.png class="noFancy" style="width: 920px;"]]

these rust libraries (rlibs) are statically compiled into the final binary but during build time they are seperate entities. especially, since `cargo-libnix` shares crates.io dependency builds beyond the ./target/ folder, we can check what the speedup would look like, when it would be used for building software in `buildRustPackage`.

## `cargo` revisions in nixpkgs

[cargo in nixmultiverse](https://nixmultiverse.com/?pkg=cargo) lists 10 to 15 revision bumps per year from 2018 to 2026 but `cargo` is only one gear in a huge set of dependencies, we need 
 to study a better metric: `buildRustPackage` implementation changes!

## `buildRustPackage` implementation changes

<script src="posts/libnix/plotly-4.0.0.min.js" charset="utf-8"></script>

<div id='myDiv' style="width:100%;height:30vh"><!-- Plotly chart will be drawn inside this DIV --></div>
<div id="stats" style="margin-top:8px;font:14px/1.4 system-ui, sans-serif;"></div>

<script>

// Parse release data (timestamp, commit, path); extract date only (YYYY-MM-DD)
const raw = `
2025-01-01T12:34:07+01:00 6973e1eb89501397cc5c2b78171d939250a5929e /nix/store/x6jyjcw4aaab9m4vs1l2nq716w1bjpk1-rust-platform-probe-1.drv
2025-01-16T10:28:36-08:00 94c4a62efb54a64344d8add9730826ca638a1398 /nix/store/4zpk87f29lcza5a9m5pbbn8f25a00l8s-rust-platform-probe-1.drv
2025-01-18T13:43:10-05:00 af961427abc6c1ce7bda0a04d8e9cb8fe1b04439 /nix/store/bwza1lszj2xrxgif6n90pxmqc04j22jd-rust-platform-probe-1.drv
2025-01-19T09:16:51+01:00 50165c4f7eb48ce82bd063e1fb8047a0f515f8ce /nix/store/zlfx0nx9ywz1i6dpis36khf3210l6v04-rust-platform-probe-1.drv
2025-01-27T05:23:23-08:00 e43d648ac1a41143237ea433867c6e61d7778e56 /nix/store/6a9b1d3xdxan06hxjial6ky4jl9a0sqa-rust-platform-probe-1.drv
2025-02-06T07:43:42+01:00 550e11f27ba790351d390d9eca3b80ad0f0254e7 /nix/store/s9jgipjvc3fxx8zg8c083f5whiml1di3-rust-platform-probe-1.drv
2025-02-15T18:30:00+08:00 90ca0500a33ac0331d8f14fed7da5cf0d1b63a72 /nix/store/cyzl9p1v2v3f1pqy29xwpykg9kykl419-rust-platform-probe-1.drv
2025-02-20T11:52:15+01:00 e493a167e1e3b7c1de669ce78dad0bd93295a83f /nix/store/v7yix0l10hhrqf0nak3qxkhdgg9z7lpq-rust-platform-probe-1.drv
2025-03-11T18:52:14+01:00 0d534853a55b5d02a4ababa1d71921ce8f0aee4c /nix/store/af5v7gcvay8yg3sk6pi28bh5c0ayg396-rust-platform-probe-1.drv
2025-03-22T17:39:24+01:00 3fcae17eabac8fdc6599d1c67d89726af3682613 /nix/store/vfv5n135x2ark8lc68aj43xkj9bi99fy-rust-platform-probe-1.drv
2025-04-02T12:08:35+03:00 41b4f451f5f6a5511cbabefdd5d0d876311ed5ef /nix/store/xxfxh75h6jg7jiyxa244br6j9rrzs5sq-rust-platform-probe-1.drv
2025-04-05T14:35:00-07:00 0a5ad4cd68209823f5c70b4bdb173529c8b027ac /nix/store/j6wif51p67aswchb6yr7ggy44ad2n0yj-rust-platform-probe-1.drv
2025-04-07T17:25:40+02:00 17b84e0b9d560f27cfd30e8ac69d87aa5a27c706 /nix/store/r3hs8z595qiidv1261pb95xagfjh6yjz-rust-platform-probe-1.drv
2025-04-08T10:00:22+03:00 68116eead86a8eb1f827024fe214f471817e931c /nix/store/j6wif51p67aswchb6yr7ggy44ad2n0yj-rust-platform-probe-1.drv
2025-04-13T16:07:22+02:00 a61952af35b8f0117238de39cdef524957d45320 /nix/store/kz5iv1y4sy8fgx9d6v2m2sqyizapil9a-rust-platform-probe-1.drv
2025-04-13T16:08:14+02:00 25d869451e1261d4aa3b2d4ed0bf0b9dc017f4c0 /nix/store/3jbi7yfnb3gb3h9rrbk4ai2balmbcsdj-rust-platform-probe-1.drv
2025-04-15T06:30:02-07:00 b05c2997b1c7e04b41dd7219e2317334c0c0726c /nix/store/lw9mp960q9k8ym4bvinhv9dmg73dy4m7-rust-platform-probe-1.drv
2025-04-27T17:15:39+03:00 0be1fa1a463efc640cddd633de966247529ead8f /nix/store/qk5l4518ds8npspr73h0qxkqbanm7wyg-rust-platform-probe-1.drv
2025-04-27T18:37:41+02:00 f739b57401a0ca4f899f4095de9edb9d9e9cc3fe /nix/store/lw9mp960q9k8ym4bvinhv9dmg73dy4m7-rust-platform-probe-1.drv
2025-05-05T09:58:25+02:00 a9245b8f22bb81675d374aed93736930f5109503 /nix/store/vjanmdig2cd823db8j1y1m92f9rnzpsn-rust-platform-probe-1.drv
2025-05-06T10:12:24-07:00 3fd3d5bc7bbfed0386efe38b8dfe9f11065ecbb6 /nix/store/j6gn8dwfy6b6likl7ix4hqrsn7szpr9m-rust-platform-probe-1.drv
2025-05-08T23:51:26-04:00 19452031ea7333974022beda3866f288d1afeaf1 /nix/store/sjq5aqzwrxd33nqw8plfgjnj2gyv8ibq-rust-platform-probe-1.drv
2025-05-14T15:30:23-04:00 add885ec41bb81260176e3368c1e2b6e3212d451 /nix/store/v5rp1pq35d6cfidv5pnsf3r3z4ihsdk8-rust-platform-probe-1.drv
2025-05-14T15:32:44-04:00 21552fcf49294c3ded07cc53db6ff2fed3044d11 /nix/store/sjq5aqzwrxd33nqw8plfgjnj2gyv8ibq-rust-platform-probe-1.drv
2025-05-15T18:42:40+02:00 e06158e58f3adee28b139e9c2bcfcc41f8625b46 /nix/store/18ca7m2j5wp2zgr4fd60jr9y955qlp6-rust-platform-probe-1.drv
2025-05-16T19:21:55+02:00 e56e0beed4312a89b60fe312ee2241f7a1627f76 /nix/store/znga7bgr2hxs12cp6ch93hxy80qq5kjx-rust-platform-probe-1.drv
2025-05-29T11:19:19-07:00 7f8ad4ffb25cbd66a69326d442c1b5d9fcbb1945 /nix/store/xbjckq9qq3kqpy7d6sx2y2xv689walk4-rust-platform-probe-1.drv
2025-06-03T08:20:49-07:00 ae61cffc494295f2e188cc53233ef066f45d6aea /nix/store/9axz452kdp1cvs9ik1w68j2xawn755hx-rust-platform-probe-1.drv
2025-06-18T10:46:23+02:00 a03f275babf1205b99825636c470a87f763f0f3f /nix/store/pgx72fjnnvvgwgfjmn4j3y740pdzdijy-rust-platform-probe-1.drv
2025-07-13T19:33:14+02:00 b47d4f01d4213715a1f09b999bab96bb6a5b675e /nix/store/hdhn1x67fnc65wjdp4748rhyb0spiszq-rust-platform-probe-1.drv
2025-07-14T20:50:13-07:00 01b8aae902554069268c0b920d84741459280c7b /nix/store/clzlgi8k8p9k2ar6myx7qrbvzwpy1l9m-rust-platform-probe-1.drv
2025-07-17T12:49:04-07:00 d1508f6f54f38660ce9e0d6e5ae73b94de246d76 /nix/store/gwalzaqa1r21h4lzsihd59plry5zq51l-rust-platform-probe-1.drv
2025-07-20T03:18:22-07:00 838a9352f8f7650a65cf2a754922c6d707b7b76d /nix/store/7rx30cwfs9mzw0sk39c45lhk62dzch5p-rust-platform-probe-1.drv
2025-07-25T15:16:39-07:00 0ca32f3372d04505fb0e6d34c2588ef0d9566ce8 /nix/store/ym30n6xp3q5injqzd604gw5fkxg6ns68-rust-platform-probe-1.drv
2025-07-26T18:59:46+02:00 17f6bd177404d6d43017595c5264756764444ab8 /nix/store/wsbg9i32cs7ncirs9r7f67lcb95s7s0n-rust-platform-probe-1.drv
2025-08-10T17:38:43-07:00 754ee2fc40577285d31fa14b895a3cf55103a925 /nix/store/a3dg7nsfp9yh5448iaqj4fi4ps7piwwm-rust-platform-probe-1.drv
2025-08-23T09:01:50+02:00 c58ada2eda15d0576e9a2ad74bd8f2318509a40f /nix/store/k9qvrqyr8v531y5a5kw5ssr6w183xrnv-rust-platform-probe-1.drv
2025-09-06T15:30:18+02:00 c773622bea64e20608b04e17b89e2288e0e19f60 /nix/store/mgkyz9xgkmg3g5hir935bdw9j5ypgkd6-rust-platform-probe-1.drv
2025-09-09T22:31:26+02:00 1779f9e0d8b45d88d7525665dd4d2a5b65041248 /nix/store/0aap1mmk6w0pd8wvgs2aw70kq2mp3qql-rust-platform-probe-1.drv
2025-09-17T12:36:21Z bc76734d04054899c71c4fd060c85a545afa7e14 /nix/store/6d6zlij6bagyq51lg7wnr28iwdbn12xx-rust-platform-probe-1.drv
2025-09-29T12:31:02Z 285ba51661a27645a252e48e7306686b8260ba94 /nix/store/bdphv02acq8rp8x74b8jp920bydkrsnl-rust-platform-probe-1.drv
2025-09-29T23:00:28Z 386f53551cfbae340edfcd6938b8d806bd8a8ddb /nix/store/qs4mn5p53py2jd1h9f5whqf4bs0zys35-rust-platform-probe-1.drv
2025-10-05T13:28:34Z 15ed8f7638116135ac9d3bd4353c482e7c539e0f /nix/store/y7cqvjrnpn51gyw97wnxifswx3b44khg-rust-platform-probe-1.drv
2025-10-13T15:25:34Z b34ad61c9c52a12ae5be284727731cf91575c4d8 /nix/store/7gd9mhp8wnm4anrsn9zmj245pkpv46cl-rust-platform-probe-1.drv
2025-10-21T07:16:28Z a91dd3189a51bbb5c7239e5790a947f9f31cb2d1 /nix/store/d0xf8dxwf4pl5swk463rcl8b4j2r6znn-rust-platform-probe-1.drv
2025-10-28T16:35:28Z 81f2a1169e23859bbc7ad6e1a4aef589b9e52a26 /nix/store/h024zbdjh81i4ld4xx18hdbvf3phiv5z-rust-platform-probe-1.drv
2025-11-05T01:00:57Z 37a08bae321cc90dfb0ce76f665853614fc507a9 /nix/store/qhyz3b09h9xgnkawksysjmw15vf5sy4y-rust-platform-probe-1.drv
2025-11-12T18:00:23Z de21549a840be528ef4763dd7dca2006caf9c11f /nix/store/ghdapsi71xxqnkd7ssy7mcdkr4nwc22c-rust-platform-probe-1.drv
2025-11-22T18:13:15Z 3dd12c46719c52e75d9f86998de15db82d27a6df /nix/store/l34nzahbf2plyfxjki681dydy0r9vk0n-rust-platform-probe-1.drv
2025-11-24T21:17:44+01:00 2493002b10ccef0880f72d7720538f91fb4f7434 /nix/store/85r7nhs9b4cjlfm6w8c0gs3fgz60xh10-rust-platform-probe-1.drv
2025-12-09T17:23:43Z 0e21d4f7e395782dbd13691d703f1b3bd662b24a /nix/store/brk00d8sycg24r36y5fszyihac10cnq3-rust-platform-probe-1.drv
2025-12-11T18:25:29Z 689380e02995917eebdadff09ff21b2ec76dfd56 /nix/store/s1j90wp1r7zlg1gjq6zl5qk4yly778yb-rust-platform-probe-1.drv
2025-12-13T16:25:28Z 9c4147152d359d797881d1e11c71bf8c2178fa7b /nix/store/9c4w34xgiyppapp6axg93hnpv767cnd6-rust-platform-probe-1.drv
2025-12-13T16:26:47Z 35aa794e296168546b020d8705c76fb415217648 /nix/store/k5ixi53rm7r04hhsgg1hb34b1rrvga15-rust-platform-probe-1.drv
2025-12-13T22:07:46Z e9af69fbc52aef7423e0ffb4366184cce475e575 /nix/store/603l3fjd5ddby02cfda0wcjcw0s1dcpw-rust-platform-probe-1.drv
2025-12-15T13:05:38Z 860a8446fce35924d49809a0a61b61afaf13f325 /nix/store/mkz9jgbidw6pbc8f7hy1b88zmkngz967-rust-platform-probe-1.drv
2025-12-17T19:41:13Z cca4ec8008dbbb571575a0aa7f044ceeb0288fb6 /nix/store/xkal0fadl99c0fbah9wdgnmxm1fnjb0n-rust-platform-probe-1.drv
2025-12-17T23:41:11Z c2884c4afb8f1ecd15a0cd16340e5cc58f17f535 /nix/store/h0h0x9qlnnvxdfwmr5858ncs5pxmsnbz-rust-platform-probe-1.drv
2025-12-21T17:59:51Z 553fe897108708abbe85dff364f9b9146e229a76 /nix/store/k7dkljs80xvf27wc8314iz4r9d1wrkw6-rust-platform-probe-1.drv
2025-12-26T00:30:06Z 57e5df3a3ab57f1d96655e30fa96f54c6748c1b5 /nix/store/nnbfcj5hz6n05jf72vg0z7shzfmbdxhd-rust-platform-probe-1.drv
2025-12-26T14:03:21Z d7aae780b39d4cbb9df69d183a70b845d97bb154 /nix/store/2xv8pq7bgi0dxh236615v34hvdan8ln8-rust-platform-probe-1.drv
2025-12-30T17:40:09Z cad22e7d996aea55ecab064e84834289143e44a0 /nix/store/946mskn8fa7wnwwwfl06q4m04w4far0z-rust-platform-probe-1.drv
`.trim();

const lines = raw.split('\n');

const releases = lines.map((line, i) => {
  const m = line.match(/^(\S+)\s+([0-9a-f]{40})\s+(\S+)$/i);
  if (!m) return null;
  const [_, ts, commit, path] = m;
  return {
    idx: i + 1,              // line number (y-axis)
    ts,                      // full timestamp
    date: ts.slice(0, 10),   // extract date only (YYYY-MM-DD)
    commit,
    path
  };
}).filter(Boolean);

// Build horizontal segments: from this date to next date at constant y = line number
const x = [];
const y = [];
const hover = [];
for (let i = 0; i < releases.length; i++) {
  const start = releases[i].date;
  const end = (i < releases.length - 1) ? releases[i + 1].date : '2025-12-31';
  const yy = releases[i].idx;

  x.push(start, end, null);
  y.push(yy, yy, null);
  const ht = `#${yy} ${releases[i].commit}<br>${releases[i].path}<br>${releases[i].ts}`;
  hover.push(ht, ht, null);
}

const data = [{
  type: 'scatter',
  mode: 'lines',
  x,
  y,
  text: hover,
  hovertemplate: 'release %{y}<br>%{x}<br>%{text}<extra></extra>',
  line: { width: 4 },
  showlegend: false
}];
var config = {responsive: true}

const layout = {
  title: { text: 'Release timeline (2025)' },
  xaxis: {
    type: 'date',
    range: ['2025-01-01', '2025-12-31'],
    tickformat: '%b',
    dtick: 'M1',
    title: { text: '2025' }
  },
  yaxis: {
    title: { text: 'release' },
    tick0: 0,   // align ticks at 0, 10, 20, ...
    dtick: 10,  // step of 10
    rangemode: 'tozero'
  },
  autosize: true,

  margin: { l: 70, r: 20, t: 60, b: 50 }
};

Plotly.newPlot('myDiv', data, layout, config);

// --- Stats: days in use per release ---
  function toUTCDate(yyyyMmDd) {
    const [Y, M, D] = yyyyMmDd.split('-').map(Number);
    return new Date(Date.UTC(Y, M - 1, D));
  }

  // Difference in calendar days (end exclusive)
  function daysBetween(startStr, endStr) {
    const ms = toUTCDate(endStr) - toUTCDate(startStr);
    return Math.max(0, ms / 86400000);
  }

  const durations = releases.map((r, i) => {
    const end = (i < releases.length - 1) ? releases[i + 1].date : '2025-12-31';
    return { idx: r.idx, days: daysBetween(r.date, end) };
  });

  const vals = durations.map(d => d.days);
  const n = vals.length;
  const sorted = [...vals].sort((a, b) => a - b);
  const mean = vals.reduce((a, b) => a + b, 0) / n;
  function percentile(p) {
    if (!n) return NaN;
    const pos = (n - 1) * p;
    const b = Math.floor(pos), r = pos - b;
    return sorted[b + 1] !== undefined ? sorted[b] + r * (sorted[b + 1] - sorted[b]) : sorted[b];
  }
  const median = percentile(0.5);
  const p25 = percentile(0.25);
  const p75 = percentile(0.75);
  const p90 = percentile(0.90);
  const min = sorted[0];
  const max = sorted[sorted.length - 1];
  const variance = vals.reduce((a, v) => a + Math.pow(v - mean, 2), 0) / (n - 1);
  const stdev = Math.sqrt(variance);
  const releasesPerMonth = n / 12;

  const statsDiv = document.getElementById('stats');
  statsDiv.innerHTML = `
    <b>Usage-days between releases <abbr title="We measure each release’s duration from its date up to (but not including) the next release date; the last runs to 2025‑12‑31.">(end exclusive)</abbr></b><br>
    <abbr title="Total number of releases included">count</abbr>=${n},
    <abbr title="Arithmetic mean of days in use">avg</abbr>=${mean.toFixed(2)}d,
    <abbr title="50th percentile; half the releases are shorter, half longer">median</abbr>=${median.toFixed(1)}d,
    <abbr title="25th percentile (first quartile); 25% are shorter">p25</abbr>=${p25.toFixed(1)}d,
    <abbr title="75th percentile (third quartile); 25% are longer">p75</abbr>=${p75.toFixed(1)}d,
    <abbr title="90th percentile; only 10% lasted longer">p90</abbr>=${p90.toFixed(1)}d,
    <abbr title="Shortest days-in-use gap">min</abbr>=${min.toFixed(0)}d,
    <abbr title="Longest days-in-use gap">max</abbr>=${max.toFixed(0)}d,
    <abbr title="Sample standard deviation; higher means more variable cadence">std</abbr>=${stdev.toFixed(2)}d<br>
    <abbr title="Average number of releases per month in 2025 (count ÷ 12)">cadence</abbr> ≈ ${releasesPerMonth.toFixed(2)} releases/month
  `;
</script>

## nixpkgs architectures

nixpkgs and `buildRustPackage` is used with these 4 different architectures (with different nixpkgs revision than below):

<table class="table table-striped table-bordered">
  <thead class="thead-dark">
    <tr>
      <th>Architecture</th>
      <th>Packages</th>
      <th>% of total</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>x86_64-linux</td>
      <td>2555</td>
      <td>28.1%</td>
    </tr>
    <tr>
      <td>aarch64-linux</td>
      <td>2517</td>
      <td>27.6%</td>
    </tr>
    <tr>
      <td>x86_64-darwin</td>
      <td>2008</td>
      <td>22.0%</td>
    </tr>
    <tr>
      <td>aarch64-darwin</td>
      <td>2007</td>
      <td>22.0%</td>
    </tr>
    <tr>
      <td><strong>Total</strong></td>
      <td><strong>9087</strong></td>
      <td><strong>100%</strong></td>
    </tr>
  </tbody>
</table>

**total package/architecture combinations:** **9087**



when changing the nix implementation of `buildRustPackage`, like when updating `rustc`/`cargo` or the toolchain, this can multiply the rebuild workload across the architectures.

## direct and indirect dependencies of the 2312 buildRustPackage rust projects

<div class="alert alert-warning" role="alert">
these values were generated using `cargo build --unit-graph -Z unstable-options > $out/unit-graph` and the parsing of the graph is sometimes not the exact same as a `cargo build` but there is nothing better ATM. i verified this for a few crates and the numbers seem to match most of the time.
</div>

[[!img posts/libnix/crate-type-distribution.jpg class="noFancy" ]]

[📊 interactive plotly graph](https://qknight.github.io/nixpkgs-datamining/crate-type-distribution.html)

<section class="stats-section">
        <h5>Project Analysis</h5>
        <ul>
          <li><strong>Total Projects Analyzed:</strong> 2300</li>
          <li><strong>Average Internal Crates per Project:</strong> 3.8</li>
          <li><strong>Average Direct Dependencies per Project:</strong> 15.7</li>
          <li><strong>Average Transitive Dependencies per Project:</strong> 138.8</li>
        </ul>

        <h5>Overall Dependency Count</h5>
        <ul>
          <li><strong>Total Internal Crates:</strong> 8759</li>
          <li><strong>Total Direct Dependencies:</strong> 36080</li>
          <li><strong>Total Transitive Dependencies:</strong> 319137</li>
        </ul>

        <h5>Total &amp; Percentage Breakdown</h5>
        <ul>
          <li><strong>Total Crates Count:</strong> 363976</li>
          <li><strong>Internal Crates:</strong> 2.4% of Total</li>
          <li><strong>Direct Dependencies:</strong> 9.9% of Total</li>
          <li><strong>Transitive Dependencies:</strong> 87.7% of Total</li>
          <li><strong>Combined Direct and Transitive Dependencies:</strong> 97.59% of Total</li>
        </ul>

        <h5>Direct Dependencies Distribution</h5>
        <ul>
          <li>
            <abbr title="50th percentile; half the projects use fewer direct dependencies">median</abbr>=12.0,
            <abbr title="25th percentile; 25% of projects use fewer direct dependencies">p25</abbr>=6.0,
            <abbr title="75th percentile; 25% of projects use more direct dependencies">p75</abbr>=21.0,
            <abbr title="90th percentile; only 10% of projects use more direct dependencies">p90</abbr>=32.0,
            <abbr title="Minimum number of direct dependencies across projects">min</abbr>=0,
            <abbr title="Maximum number of direct dependencies across projects">max</abbr>=162
          </li>
          <li>
            <abbr title="75th percentile">p75</abbr> of projects use &lt;= 21.0 direct dependencies
          </li>
        </ul>

        <h5>Internal Crates Distribution</h5>
        <ul>
          <li>
            <abbr title="50th percentile; half the projects have fewer internal crates">median</abbr>=1.0,
            <abbr title="25th percentile; 25% of projects have fewer internal crates">p25</abbr>=1.0,
            <abbr title="75th percentile; 25% of projects have more internal crates">p75</abbr>=2.0,
            <abbr title="90th percentile; only 10% of projects have more internal crates">p90</abbr>=7.0,
            <abbr title="Minimum number of internal crates across projects">min</abbr>=1,
            <abbr title="Maximum number of internal crates across projects">max</abbr>=257
          </li>
          <li>
            <abbr title="75th percentile">p75</abbr> of projects use &lt;= 2.0 main crates
          </li>
        </ul>
      </section>

## finding identical crates.io dependencies in 2312 buildRustPackage rust projects

a graph showing similar crates.io dependencie configurations in 2312 buildRustPackage rust projects.

[[!img posts/libnix/libnix-cargo-nixpkgs-study.jpg class="noFancy" ]]

[📊 interactive d3 graph (30s load time)](https://qknight.github.io/nixpkgs-datamining/index.html)

findings:

* nixpkgs [1c3d5a53f03f2eb5677f6f3b34f0ef31261ba485](https://github.com/NixOS/nixpkgs/commit/1c3d5a53f03f2eb5677f6f3b34f0ef31261ba485) we find **2574** rust programs compiled via `buildRustPackage`.

* with **2312** (out of the 2574) i could use for statistics (that is 90% of all `buildRustPackages` usages)

* these **2312 rust projects** have **360909 crates.io dependencies** and on average each project has **360909/2312 = 158 dependencies**

* out of 360909 crates.io dependencies, only **44248 are unique crates.io dependencies**, meaning there is a huge set of crates which are compiled with an identical configuration

# hypothesis

`cargo-libnix` already is capable of reusing compiled libraries and thus we would have to build **8.1 times less dependencies**! it remains to be seen if this 8.1 factor translates in 8.1 compile time and it could be more or even less.

* hydra.nixos.org on average, would then only have to compile **158/8 = ~20** dependencies per rust project when picking up a new project and start working on them and instead they would use binary substitudes

* in the **age of AI** `cargo+libnix` could speed up things even more as agents are far more wasteful with repository checkouts and rebuilds than humans are (a hunch of mine, needs proper backing)

* rustc supports incremental builds and we could even wrap that into dynamic derivations

it would be interesting to compile a list of *build times*, *source code checkout size* and *binary store path size* for each of the 44248 unique crates.io crates and then use these build statistics to get a measurement on the actual combined build times and disk space impacts.

# summary

using the integration of `cargo+libnix` could lead to **improved build efficiency**, **faster onboarding**, and a **more streamlined developer experiences**.

shoutout to the nixpkgs maintainers: excellent work! without your diligent efforts in maintaining this extensive collection of software, i wouldn't have been able to gather such valuable data.