Checking, Running, and Testing

While we work on a project we mostly use three commands: check to compile the project and report errors without generating code, run to compile the project and run its main function, and test to run every function marked with @Test.

Checking for Errors

We can check the project for compiler errors with the check command:

Found 'flix.toml'. Checking dependencies...
Resolving Flix dependencies...
Downloading Flix dependencies...
Resolving Maven dependencies...
  Running Maven dependency resolver.
Downloading external jar dependencies...
Dependency resolution completed.

Flix begins every command by resolving the dependencies of the project, which is what these lines report. Our project has no dependencies yet, so there is nothing to download. We leave these lines out of the examples that follow.

If the project does not compile, Flix reports the errors instead. If we add a function that uses and on an integer:

def isPositive(x: Int32): Bool = x and true

then check reports:

-- Type Error [E7796] -------------------------------------------- src/Main.flix

>> Unexpected type: expected 'Bool', found 'Int32'.

5 | def isPositive(x: Int32): Bool = x and true
                                     ^
                                     unexpected type

During development, the check command is preferable to the build command, because check skips code generation and hence is significantly faster.

Running the Program

We can compile and run the project with the run command. We do not have to build anything first:

Hello World!

The run command runs the main function of the project. See The Main Function for what main may look like.

Running the Tests

We can run the tests with the test command. Flix collects every function marked with @Test, runs it, and prints a summary:

Running 1 tests...

   PASS  test01 1.3ms

Passed: 1, Failed: 0. Skipped: 0. Elapsed: 3.8ms.

See Test Framework for how to write tests.

Generating Documentation

We can generate API documentation for the project with the doc command. Flix writes the documentation to the build/doc directory:

build
└── doc
    ├── favicon.png
    ├── index.html
    ├── index.js
    └── styles.css

We read it by opening build/doc/index.html in a browser.

Formatting the Source Code

We can format the source code of the project with the format command. The command rewrites every file in src and test in place. If src/Main.flix reads:

def   main( ) : Unit \ IO =
  println(  "Hello World!" )

def add(x:Int32,y:Int32):Int32=x+y

then after format it reads:

def main(): Unit \ IO =
    println("Hello World!")

def add(x: Int32, y: Int32): Int32 = x + y

If the project does not compile, format reports the errors and leaves the files untouched.

Printing Statistics

We can print statistics about the project with the stat command:

<unnamed> 0.1.0

2 files, 5 lines: 4 code, 1 comment, 0 blank.
0 modules, 2 defs: 0 pure, 2 effectful, 0 effect polymorphic.
0 types, 0 traits, 0 instances, 0 effects.

The header names the package by the repository it is published from, or <unnamed> when it declares none, followed by its version.

Once the program does what we want, we are ready to build something we can ship.

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