--- title: A new chapter for the Nix language, courtesy of WebAssembly description: Determinate Nix introduces `builtins.wasm`, a new experimental feature that lets Nix expressions call WebAssembly functions directly. This solves long-standing... canonical: https://daily.dev/posts/a-new-chapter-for-the-nix-language-courtesy-of-webassembly-a613el2y3 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: A new chapter for the Nix language, courtesy of WebAssembly | daily.dev og:description: Determinate Nix introduces `builtins.wasm`, a new experimental feature that lets Nix expressions call WebAssembly functions directly. This solves long-standing... og:url: https://daily.dev/posts/a-new-chapter-for-the-nix-language-courtesy-of-webassembly-a613el2y3 og:image: https://api.daily.dev/og/posts/A613el2Y3.png og:image:alt: A new chapter for the Nix language, courtesy of WebAssembly og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # A new chapter for the Nix language, courtesy of WebAssembly **[Lobsters](https://daily.dev/sources/lobsters)** · 8 min read · 1 upvotes · 0 comments ## Summary Determinate Nix introduces `builtins.wasm`, a new experimental feature that lets Nix expressions call WebAssembly functions directly. This solves long-standing limitations of the Nix language—such as the lack of a YAML parser—without requiring C++ plugins, upstream approval, or expensive import-from-derivation workarounds. Wasm modules can be written in Rust, C++, Zig, or any Wasm-targeting language. The approach delivers dramatic performance gains (240x speedup and 151x memory reduction for a Fibonacci benchmark vs. pure Nix). Wasm's deterministic execution model preserves Nix's reproducibility guarantees. The feature uses Wasmtime with Cranelift JIT under the hood. A PR to upstream Nix has also been opened. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: --- Tags: [#rust](https://daily.dev/tags/rust), [#webassembly](https://daily.dev/tags/webassembly) [View this post on daily.dev](https://daily.dev/posts/a-new-chapter-for-the-nix-language-courtesy-of-webassembly-a613el2y3) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"A new chapter for the Nix language, courtesy of WebAssembly","url":"https://daily.dev/posts/a-new-chapter-for-the-nix-language-courtesy-of-webassembly-a613el2y3","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/a-new-chapter-for-the-nix-language-courtesy-of-webassembly-a613el2y3"},"datePublished":"2026-03-06T14:38:13.703Z","dateModified":"2026-03-06T14:38:43.876Z","description":"Determinate Nix introduces `builtins.wasm`, a new experimental feature that lets Nix expressions call WebAssembly functions directly. 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