Faber build tool

The faber CLI is the primary entry point for building, checking, running, formatting, and testing Faber source. It wraps the Radix compiler into an ergonomic developer tool.

Core commands

Command	Purpose
`faber build <path>`	Compile a package to a target backend (default: Rust)
`faber check <path>`	Type-check without emitting code
`faber run <path>`	Build and execute
`faber test <path>`	Run proba test suites
`faber format <path>`	Apply canonical formatting
`faber explain <code>`	Explain a diagnostic code
`faber emit <path>`	Emit source in a target surface

Building a package

faber build my-package/ -t rust

The -t flag selects the codegen target. Supported targets include rust (default), wasm, typescript, and go.

Checking without emitting

faber check my-package/

Runs the full front end (lex → parse → typecheck → MIR lowering) without producing output artifacts. Use this in CI and editor integrations.

Running tests

faber test my-package/

Compiles all probandum suites in the package to Rust #[test] functions and runs them via Cargo. Inline tests live alongside source code — no separate test binary is needed.

Formatting

faber format my-package/

Applies the canonical Faber formatter. The formatter enforces consistent layout: one declaration per line, canonical spacing, and standardized keyword surfaces.

Explaining diagnostics

faber explain SEM001

Prints a human-readable explanation of any diagnostic code the compiler can emit. Useful for learning what an error means and how to fix it.