Add Capa to Serious Projects

[nelsonduarte]

• Use a meaningful title for the pull request. Include the name of the resource added.
• Add a short sentence on why do you think the resource you're adding is awesome!
• Make sure your addition maintains the alphabetical order of the list.
• Make sure your addition contains a description besides the link.

Why this is awesome

Capa is a capability-typed programming language with a working transpiler (Python target), 946-test CI matrix across Linux / macOS / Windows x Python 3.10 / 3.12 / 3.14, beta release status (v0.8.2-beta), full website, and LSP server.

The distinguishing design choice is that every function declares its authority (Fs, Net, Env, Clock, Random, plus user-defined capabilities) as part of the type. The compiler then emits standard supply-chain governance artefacts (CycloneDX SBOM, SPDX SBOM, CycloneDX VEX, SLSA L1 provenance) at per-function granularity from those signatures, grounded in the type system rather than a separate static analyser.

Website: https://capa-language.com/

Alphabetical position observed: between BOLT and ChezScheme's Compiler.