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areas
areas
 
 
arrays
arrays
 
 
channels-sum
channels-sum
 
 
channels-timeout
channels-timeout
 
 
channels
channels
 
 
curried-funcs
curried-funcs
 
 
datalog-constraints
datalog-constraints
 
 
datalog-lattice-semantics
datalog-lattice-semantics
 
 
fibonacci
fibonacci
 
 
files
files
 
 
generics
generics
 
 
helloworld
helloworld
 
 
hofs
hofs
 
 
impure-funcs
impure-funcs
 
 
interpreter
interpreter
 
 
lambda-calculus
lambda-calculus
 
 
lists
lists
 
 
mutability
mutability
 
 
named-arguments
named-arguments
 
 
namespaces
namespaces
 
 
primes
primes
 
 
purity-reflexion
purity-reflexion
 
 
records
records
 
 
trees
trees
 
 
type-aliases
type-aliases
 
 
type-matches
type-matches
 
 
Makefile.inc
Makefile.inc
 
 
README.md
README.md
 
 
build.bat
build.bat
 
 
common.gradle
common.gradle
 
 
pom.xml
pom.xml
 
 

README.md

Flix Examples ↩

Flix project Directory examples\ contains Flix code examples coming from various websites - mostly from the Flix project.

We currently support five ways to build/run/test our Flix code examples:

Build tool Build file Parent file Environment(s)
cmd.exe build.bat   MS Windows
sh.exe build.sh   Any a)
ant.bat build.xml   Any
gradle.exe build.gradle common.gradle Any
make.exe b) Makefile Makefile.inc Any
a) Here "Any" means "tested on MS Windows / Cygwin / MSYS2 / Unix"
b) Default shell is /bin/sh as described in the online document Choosing the Shell.
 

🔎 Command examples\build.bat allows us to clean, build and run all projects in directory examples\, for instance before updating our Github repository flix-examples with local changes.

areas Example ▴

This project has the following directory structure :

> tree /a /f . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle  (..\common.gradle)
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile      (..\Makefile.inc)
|   pom.xml
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat -verbose run 3 generates the target file areas.jar from the Flix source file src\main\Main.flix and executes it :

> build -verbose run
Copy 1 Flix source file to directory "target\areas\src\"
Compile 1 Flix source file into directory "target\areas\build\"
Create archive file "target\areas\artifact\areas.jar"
Execute Flix program "target\areas\artifact\areas.jar"
2 :: 6 :: Nil
2 :: 6 :: Nil

During compilation we run the two Flix commands build 1 and build-jar to successively generate the Java class files in subdirectory target\areas\build\ and the target file target\areas\artifact\areas.jar :

> tree /a /f areas | findstr /v /b [A-Z]
\---areas
   |   .gitignore
   |   areas.jar-test.txt
   |   flix.toml
   |   LICENSE.md
   |   README.md
   +---artifact
   |       areas.jar
   +---build
   |   \---class  (*.class)
   +---lib
   |   \---cache
   +---src
   |       Main.flix
   \---test
           TestMain.flix

Command build.bat -verbose test generates the target file target\areas\areas.jar from the Flix source files src\main\Main.flix and src\test\TestMain.flix and runs the tests:

> build -verbose test
Copy 1 Flix source file to directory "target\areas\src\"
Copy 1 Flix test source file to directory "target\areas\test\"
Compile 1 Flix source file and 1 Flix test source file
Create archive file "target\areas\artifact\areas.jar"
Execute tests for Flix program "target\areas\artifact\areas.jar"
Running 2 tests...
 
   PASS  test01 415,8us
   PASS  test02 89,5us
 
Passed: 2, Failed: 0. Skipped: 0. Elapsed: 4,0ms.

🔎 We provide other ways to build/run/test our Flix code examples :

  1. Command make.exe reads its configuration from the two configuration files Makefile and Makefile.inc (we can use option --silent to hide the executed commands): 
     > make run
[ -d "target/areas" ] || "C:/opt/Git/usr/bin/mkdir.exe" -p "target/areas"
cd "target/areas"; \
     [ -d "build" ] || "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix.jar" init && \
     "C:/opt/Git/usr/bin/rm.exe" -f "src/Main.flix" && \
     "C:/opt/Git/usr/bin/cp.exe" -r "F:/examples/areas/src/main/." src && \
     "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix.jar" build && \
     "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix.jar" build-jar
"C:/opt/jdk-temurin-21.0.4_7/bin/java.exe"  -jar "target/areas/artifact/areas.jar"
2 :: 6 :: Nil
2 :: 6 :: Nil
 
> make --silent test
Running 2 tests...
 
   PASS  test01 806,3us
   PASS  test02 115,4us
 
Passed: 2, Failed: 0. Skipped: 0. Elapsed: 6,3ms.
  2. Command gradle.bat reads its configuration from the two configuration files build.gradle and common.gradle : 
    > gradle run
 
> Task :compileFlix
 
> Task :run
2 :: 6 :: Nil
2 :: 6 :: Nil
 
BUILD SUCCESSFUL in 15s
7 actionable tasks: 7 executed
  3. Command sh.exe targets a Unix-like environment in the same way as build.bat targets the Windows environment: 
    > sh ./build.sh -verbose run
Initialize directory "target/areas"
Copy Flix source files to directory "target/areas/src"
Copy Flix test source files to directory "target/areas/test"
Compile 1 Flix source file to directory "target/areas/build"
Create archive file "target/areas/artifact/areas.jar"
Execute the JAR file "target/areas/artifact/areas.jar"
2 :: 6 :: Nil
2 :: 6 :: Nil

channels Example ▴

This project has the following directory structure :

> tree /a /f . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat -verbose run generates the target file target\channels\artifact\channels.jar from the Flix source file src\main\Main.flix and executes the target file :

> build -verbose run
Copy 1 Flix source file to directory "target\channels\src\"
Compile 1 Flix source file to directory "target\channels\build\"
Create archive file "target\channels\artifact\channels.jar"
Extract Flix runtime from archive file "C:\opt\flix\flix.jar"
Add Flix runtime to archive file "target\channels\artifact\channels.jar"
Execute Flix program "target\channels\artifact\channels.jar"
1 :: 2 :: 3 :: Nil

Note: The Flix command build-jar does not add the Flix runtime to the generated archive file target\channels\channels.jar, so we need to update it with class files extracted from flix.jar and belonging to package ca.uwaterloo.flix.runtime.
Without that additional step we get the following runtime error :

> build -verbose run
Copy 1 Flix source file to directory "target\channels\src\"
Compile 1 Flix source file
Create archive file "target\channels\channels.jar"
Execute Flix program "target\channels\channels.jar"
Exception in thread "main" java.lang.NoClassDefFoundError: ca/uwaterloo/flix/runtime/interpreter/Channel
        at Def%main%.invoke(Unknown Source)
        at Cont%Obj.unwind(Cont%Obj)
        at Ns.m_main%(Unknown Source)
        at Main.main(Main)
Caused by: java.lang.ClassNotFoundException: ca.uwaterloo.flix.runtime.interpreter.Channel
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
        ... 4 more
Error: Failed to execute Flix program "target\channels\artifact\channels.jar"

datalog-constraints Example▴

This project has the following directory structure :

> tree /f /a . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat -verbose run generates the target file target\datalog-constraints\datalog-constraints.jar from the Flix source file src\main\Main.flix and executes the target file :

> build -verbose run
Copy 1 Flix source file to directory "target\datalog-constraints\src\"
Compile 1 Flix source file into directory "target\datalog-constraints\build\"
Create archive file "target\datalog-constraints\datalog-constraints.jar"
Execute Flix program "target\datalog-constraints\datalog-constraints.jar"
(C++, x86) :: (MiniScala, C++) :: (MiniScala, x86) :: (Scala, C++) :: (Scala, MiniScala) :: (Scala, x86) :: Nil

fibonacci Example ▴

This example has the following directory structure :

> tree /f /a . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
|   pom.xml
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat -verbose run generates the target file target\fibonacci\fibonacci.jar from the Flix source file src\main\Main.flix and executes the target file :

> build -verbose run
Copy 1 Flix source file to directory "target\fibonacci\src\"
Compile 1 Flix source file into directory "target\fibonacci\build\"
Create archive file "target\fibonacci\artifact\fibonacci.jar"
Execute Flix program "target\fibonacci\artifact\fibonacci.jar"
0 :: 1 :: 1 :: 2 :: 3 :: 5 :: 8 :: 13 :: 21 :: 34 :: Nil

Command build.bat -verbose test generates the target file target\fibonacci\fibonacci.jar from the Flix source files src\main\Main.flix and src\test\TestMain.flix and runs the tests:

> build -verbose test
Copy 1 Flix source file to directory "target\fibonacci\src\"
Copy 1 Flix test source file to directory "target\fibonacci\test\"
Compile 1 Flix source file and 1 Flix test source file
Create archive file "target\fibonacci\artifact\fibonacci.jar"
Execute tests for Flix program "target\fibonacci\artifact\fibonacci.jar"
Running 1 tests...

   PASS  test01 1,0ms
 
Passed: 1, Failed: 0. Skipped: 0. Elapsed: 5,8ms.

lambda-calculus Example

This example is slightly more complex than the others because it contains several source files, including the Scala source file Counter.scala.

> tree /a /f . | findstr /v /b [A-Z]
|   build.bat
|   build.sh
|   build.gradle   (..\common.gradle)
|   gradle.properties
|   Makefile       (..\Makefile.inc)
\---src
    +---main
    |       Counter.scala
    |       lambda-calculus.flix
    |       Main.flix
    \---test
            TestMain.flix

🔎 Counter.scala implements the stateful object Counter with one single method getNext(). In source file lambda-calculus.flix we call getNext() instead of ??? (the "unimplemented" function) inside function freshVar() in order to obtain a runnable example :

def freshVar(): Int32 = // ???
    import static Counter.getNext(): Int32 \ {};
    getNext()

Concretely we perform two additional steps before calling the Flix commands build and build-jar:

  • we compile Counter.scala into directory target\lambda-calculus\lib\ with the Scala command scalac.bat.
  • we create target\lambda-calculus\lib\lib-lambda-calculus.jar with the Java command jar.exe.
> build -debug clean run
[build] Properties : _PROJECT_NAME=lambda-calculus
[build] Options    : _NIGHTLY=0 _VERBOSE=0
[build] Subcommands: _COMMANDS= clean compile run
[build] Variables  : "FLIX_HOME=C:\opt\flix"
[build] Variables  : "JAVA_HOME=C:\opt\jdk-temurin-21.0.4_7"
[build] Variables  : "SCALA_HOME=C:\opt\scala-2.13.12"
[build] rmdir /s /q "F:\examples\lambda-calculus\target"
[build] 00000000000000 Target : 'F:\examples\lambda-calculus\target\lambda-calculus\lambda-calculus.jar'
[build] 20220924220123 Sources: 'F:\examples\lambda-calculus\src\main\*.flix'
[build] _ACTION_REQUIRED=1
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -jar "C:\opt\flix\flix.jar" init
[build] xcopy /s /y "F:\examples\lambda-calculus\src\main" "F:\examples\lambda-calculus\target\lambda-calculus\src\" 1>NUL
[build] "C:\opt\scala-2.13.12\bin\scalac.bat" -cp "C:\opt\flix\flix.jar" -d "F:\examples\lambda-calculus\target\lambda-calculus\lib"  "F:\examples\lambda-calculus\target\lambda-calculus\src\Counter.scala"
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\jar.exe" cf "F:\examples\lambda-calculus\target\lambda-calculus\lib\lib-lambda-calculus.jar" -C "F:\examples\lambda-calculus\target\lambda-calculus\lib" .
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -cp "F:\examples\lambda-calculus\target\lambda-calculus\build" -jar "C:\opt\flix\flix.jar" build --explain
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -jar "C:\opt\flix\flix.jar" build-jar
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" "-Xbootclasspath/a:F:\examples\lambda-calculus\target\lambda-calculus\lib\lib-lambda-calculus.jar" -jar "F:\examples\lambda-calculus\target\lambda-calculus\lambda-calculus.jar"
Abs(1, Abs(0, Var(0)))
[build] _EXITCODE=0

mutability Example ▴

This example has the following directory structure :

> tree /f /a . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat -debug run generates the target file target\mutability\mutability.jar from the Flix source file src\Main.flix and runs the target file :

> build -debug run
[build] Properties : _PROJECT_NAME=mutability
[build] Options    : _NIGHTLY=0 _VERBOSE=0
[build] Subcommands: _COMMANDS= compile run
[build] Variables  : "FLIX_HOME=C:\opt\flix"
[build] Variables  : "JAVA_HOME=C:\opt\jdk-temurin-21.0.4_7"
[build] Variables  : "SCALA_HOME=C:\opt\scala-2.13.14"
[build] 00000000000000 Target : 'F:\examples\mutability\target\mutability\mutability.jar'
[build] 20220908185859 Sources: 'F:\examples\mutability\src\*.flix'
[build] _ACTION_REQUIRED=1
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -jar "C:\opt\flix\flix.jar" init
[build] xcopy /s /y "F:\examples\mutability\src" "F:\examples\mutability\target\mutability\src\" 1>NUL
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -jar "C:\opt\flix\flix.jar" build
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe" -jar "C:\opt\flix\flix.jar" build-jar
[build] "C:\opt\jdk-temurin-21.0.4_7\bin\java.exe"  -jar "F:\examples\mutability\target\mutability\mutability.jar"
1 :: 2 :: 3 :: Nil
[build] _EXITCODE=0

named-arguments Example ▴

Command gradle.bat run (build.gradle/common.gradle) generates the target file target\named-arguments\named-arguments.jar from the Flix source file src\main\named-arguments.flix and executes the target file :

> gradle -Dnightly clean run
 
> Configure project :
Nightly build 'flix-2024-02-10.jar' was selected
 
> Task :compileFlix
 
> Task :run
Player(1, 0)
 
BUILD SUCCESSFUL in 18s
8 actionable tasks: 8 executed

primes Example

This example has the following directory structure :

> tree /f /a . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat run generates the target file target\primes\primes.jar from the Flix source file src\main\Main.flix and executes the target file :

> build run
Using 'primes'
2 :: 3 :: 5 :: 7 :: 11 :: 13 :: 17 :: 19 :: 23 :: 29 :: Nil
Using 'primes2'
2 :: 3 :: 5 :: 7 :: 11 :: 13 :: 17 :: 19 :: 23 :: 29 :: Nil

Command build.bat -verbose test generates the target file target\primes\primes.jar from the Flix source files src\main\Main.flix and src\test\TestMain.flix and runs the tests:

> build -verbose test
Running 2 tests...
 
   PASS  test01 892,4us
   PASS  test02 278,4us

Passed: 2, Failed: 0. Skipped: 0. Elapsed: 5,7ms.

records Example ▴

This example has the following directory structure :

> tree /f /a . | findstr /v /b [A-Z]
|   build.bat
|   build.gradle
|   build.sh
|   build.xml
|   gradle.properties
|   Makefile
|   pom.xml
\---src
    +---main
    |       Main.flix
    \---test
            TestMain.flix

Command build.bat run generates the target file target\records\artifact\records.jar from the Flix source file src\main\Main.flix and executes the target file :

> build run
r1 = { 1, 2 }
r2 = { 1, 2 }
r1 == r2: true
r3 = { 3, 2 }

trees Example

Command build.bat run generates the target file target\trees\artifact\trees.jar from the Flix source file src\main\Main.flix and executes the target file :

> build run
10

type-aliases Example

Command build.bat run generates the target file target\type-aliases\artifact\type-aliases.jar from the Flix source file src\main\Main.flix and executes the target file :

> build run
Map#{1 => Hello, 2 => World}
Map#{1 => Ok(123), 2 => Err(Hello)}

Footnotes ▴

[1] Flix commands ↩

We give option --help to display the Flix commands : 
> "%JAVA_HOME%\bin\java.exe" -jar "%FLIX_HOME%\flix.jar" --help
The Flix Programming Language v0.49.0
Usage: flix [init|check|build|build-jar|build-pkg|run ↲
 |benchmark|test|repl|install|lsp] [options] <args>...
 
Command: init
  creates a new project in the current directory.
Command: check
  checks the current project for errors.
Command: build
  builds (i.e. compiles) the current project.
Command: build-jar
  builds a jar-file from the current project.
Command: build-pkg
  builds a fpkg-file from the current project.
Command: run
  runs main for the current project.
Command: doc
  generates API documentation.
Command: benchmark
  runs the benchmarks for the current project.
Command: test
  runs the tests for the current project.
Command: repl
  starts a repl for the current project, or provided Flix source files.
Command: lsp port
  starts the LSP server and listens on the given port.
  port
 
  --args <a1, a2, ...>     arguments passed to main. Must be a single quoted string.
  --entrypoint <value>     specifies the main entry point.
  --explain                provides suggestions on how to solve a problem.
  --github-token <value>   API key to use for GitHub dependency resolution.
  --help                   prints this usage information.
  --json                   enables json output.
  --listen <port>          starts the socket server and listens on the given port.
  --no-install             disables automatic installation of dependencies.
  --threads <value>        number of threads to use for compilation.
  --yes                    automatically answer yes to all prompts.
  --version                prints the version number.
 
The following options are experimental:
  --Xbenchmark-code-size   [exp.] benchmarks the size of the generated JVM files.
  --Xbenchmark-incremental
                           [exp.] benchmarks the performance of each compiler phase in incremental mode.
  --Xbenchmark-phases      [exp.] benchmarks the performance of each compiler phase..
  --Xbenchmark-frontend    [exp.] benchmarks the performance of the frontend.
  --Xbenchmark-throughput  [exp.] benchmarks the performance of the entire compiler.
  --Xlib <value>           [exp.] controls the amount of std. lib. to include (nix, min, all).
  --Xno-optimizer          [exp.] disables compiler optimizations.
  --Xprint-phase <value>   [exp.] prints the AST(s) after the given phase(s). 'all' prints all ASTs.
  --Xbdd-threshold <value>
                           [exp.] sets the threshold for when to use BDDs.
  --Xno-bool-cache         [exp.] disables Boolean caches.
  --Xno-bool-specialcases  [exp.] disables hardcoded Boolean unification special cases.
  --Xno-bool-table         [exp.] disables Boolean minimization via tabling.
  --Xno-bool-unif          [exp.] disables Boolean unification. (DO NOT USE).
  --Xno-qmc                [exp.] disables Quine McCluskey when using BDDs.
  --Xsummary               [exp.] prints a summary of the compiled modules.
  --Xparser                [exp.] disables new experimental lexer and parser.
 
  <file>...                input Flix source code files, Flix packages, and Java archives.

[2] Flix-managed project directory ↩

Flix project directories must have a special layout enforced by the Flix command init. For instance the documentation files LICENSE.md and README.md must exist inside the project directory in order to run the Flix commands build, build-jar, etc. 
> tree /a /f . | tail -n +3
F:\EXAMPLES\SAMPLE
|   LICENSE.md, README.md
+---build
+---lib
+---src
|       Main.flix
\---test
        TestMain.flix

[3] Flix nightly builds ↩

We can select the latest nightly build of the Flix library instead of the release version to generate the target JAR file for each of the above examples :
  • build.bat supports the -nightly option.
  • make.exe supports the NIGHTLY=1 property.
  • gradle.bat supports the -Dnightly property.
Here is how it works with the areas example : 
> build -verbose -nightly clean run
Nightly build "flix-2024-08-16.jar" was selected
Delete directory "target"
Initialize Flix project directory "target\areas"
Copy 1 Flix source file to directory "target\areas\src\"
Compile 1 Flix source file into directory "target\areas\build\"
Create archive file "target\areas\artifact\areas.jar"
Execute Flix program "target\areas\artifact\areas.jar"
2 :: 6 :: Nil
2 :: 6 :: Nil

> make NIGHTLY=1 run
[ -d "target/areas" ] || "C:/opt/Git/usr/bin/mkdir.exe" -p "target/areas"
cd "target/areas"; \
        [ -d "build" ] || "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix-2024-08-16.jar" init && \
        "C:/opt/Git/usr/bin/rm.exe" -f "src/Main.flix" && \
        "C:/opt/Git/usr/bin/cp.exe" -r "F:/examples/areas/src/main/." src && \
        "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix-2024-08-16.jar" build && \
        "C:/opt/jdk-temurin-21.0.4_7/bin/java.exe" -jar "C:\opt\flix\flix-2024-08-16.jar" build-jar
"C:/opt/jdk-temurin-21.0.4_7/bin/java.exe"  -jar "target/areas/areas.jar"
2 :: 6 :: Nil
2 :: 6 :: Nil

> gradle -Dnightly run
 
> Configure project :
Nightly build 'flix-2024-08-16.jar' was selected
 
&g; Task :compileFlix
 
> Task :run
2 :: 6 :: Nil
2 :: 6 :: Nil

BUILD SUCCESSFUL in 15s
7 actionable tasks: 7 executed

mics/January 2025 ▲