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FScript

Running, Checking, and Compiling

Use check when you want validation, run when you want the broadest current execution path, and compile when you want a native executable for the supported subset.

fscript check

check is the safest first step while you are writing code.

It currently validates:

  • lexing and parsing
  • name resolution
  • typechecking
  • effect analysis
  • user-module import graphs

Example:

Terminal window
cargo run -p fscript-cli -- check src/main.fs

Use this when you want fast feedback without executing effects.

fscript run

run executes an entrypoint through the current shared IR and interpreter path.

Example:

Terminal window
cargo run -p fscript-cli -- run src/main.fs

This is the broadest execution path today and is the best default while the native compiler is still expanding feature parity.

fscript compile

compile emits a native executable:

Terminal window
cargo run -p fscript-cli -- compile src/main.fs ./main

Important current nuance:

  • there is a real native backend slice
  • there is also a broader embedded-runner bridge
  • compile therefore covers more than the narrowest real-native path, but less than the long-term goal of full parity

For day-to-day iteration:

  1. write or edit a .fs file
  2. run fscript check
  3. run fscript run
  4. compile only when you need an executable artifact or want to test current compile coverage

Comparison to TypeScript workflows

If you are used to tsc --noEmit, node, and bundlers:

  • check is closest to tsc --noEmit
  • run is the closest equivalent to “execute directly”
  • compile is closer to producing a native binary than transpiling to JavaScript

Choosing the right command

Use check when:

  • you only want validation
  • the program has side effects you do not want to trigger yet

Use run when:

  • you want the most complete current execution path
  • you are testing behavior rather than binary output

Use compile when:

  • you want a standalone executable
  • you are explicitly testing compile coverage
  • you are comfortable with the current implementation-status caveats

Next step

See the CLI Overview for command-by-command details.