README.md

Lutz Hühnken's Flix Examples ↩

Directory lutz-examples\ contains Flix code examples presented in Lutz Hühnken's article "Flix for Java programmers" (June 2022).

🔎 Visit the Codeberg repository 2022-06-24-flix-for-java-programmers to get the original Flix code examples.

We made the following changes resp. additions in comparison to the original Flix code examples :

• The source files have been updated ¹ to successfully compile with the latest version of the Flix compiler.
• Each example has the same directory layout as the Flix code examples presented in document examples\README.md.
• Each example includes a basic test suite (directory src\test\).
• We provide several build scripts to build, run and test the Flix code examples.

Currently we provide four ways to build, run and test the Flix code examples :

Build tool	Build file	Parent file	Environment(s)
cmd.exe	build.bat		MS Windows
sh.exe	build.sh		Any a)
gradle.exe	build.gradle	common.gradle	Any
make.exe	Makefile	Makefile.inc	Any

^a) Here "Any" means "tested on MS Windows / Cygwin / MSYS2 / Unix".
 

channels Example ▴

This project has the following directory structure :

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

Command build-verbose run generates and executes the target file channels.jar :

> build -verbose run
Initialize Flix project directory "target\channels"
Copy 1 Flix source file to directory "target\channels\src\"
Compile 1 Flix source file into directory "target\channels\build\"
Create archive file "target\channels\channels.jar"
Extract Flix runtime from archive file "%FLIX_HOME%\flix.jar"
Add Flix runtime to archive file "target\channels\channels.jar"
Execute Flix program "target\channels\channels.jar"
29
39
[...]
72
35
done

Command build -verbose test generates the target file target\channels\channels.jar from the Flix sources files src\main\channels.flix and src\test\channelsTest.flix and runs the test suite :

> build -verbose test
Copy 1 Flix source file to directory "target\channels\src\"
Copy 1 Flix test source file to directory "target\channels\test\"
Compile 1 Flix source file and 1 Flix test source file
Create archive file "target\channels\channels.jar"
Extract Flix runtime from archive file "C:\opt\flix-0.43.0\flix.jar"
Add Flix runtime to archive file "target\channels\channels.jar"
Execute tests for Flix program "target\channels\channels.jar"
Running 1 tests...

   PASS  test01 384,1us

Passed: 1, Failed: 0. Skipped: 0. Elapsed: 6,9ms.

🔎 Command build.sh is the counterpart of the above batch file build.bat for Unix-like environments; for instance :  

> bash -c "./build.sh -verbose run"
Initialize directory "target/channels"
Copy Flix source files to directory "target/channels/src"
Copy Flix test source files to directory "target/channels/test"
Compile 1 Flix source files to directory "target/channels/build"
Create archive file "target/channels/channels.jar"
Extract class files from archive file "C:/opt/flix-0.43.0/flix.jar"
Update archive file "target/channels/channels.jar"
Execute the JAR file "target/channels/channels.jar"
20
...
7
done
 
> bash --version | findstr version
GNU bash, version 5.2.15(1)-release (x86_64-pc-linux-gnu)
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

datalog Example ▴

Command make run (Makefile/Makefile.inc) generates the target file target\datalog\datalog.jar from the Flix source file src\main\datalog.flix and executes the target file :

> make run
[ -d "target/datalog" ] || "%GIT_HOME%/usr/bin/mkdir.exe" -p "target/datalog"
cd "target/datalog"; \
        [ -d "build" ] || "%JAVA_HOME%/bin/java.exe" -jar "%FLIX_HOME%/flix.jar" init && \
        "%GIT_HOME%/usr/bin/rm.exe" -f "src/Main.flix" && \
        "%GIT_HOME%/usr/bin/cp.exe" -r "F:/lutz-examples/datalog/src/main/." src && \
        "%JAVA_HOME%/bin/java.exe" -jar "%FLIX_HOME%/flix.jar" build && \
        "%JAVA_HOME%/bin/java.exe" -jar "%FLIX_HOME%/flix.jar" build-jar
"%JAVA_HOME%/bin/java.exe"  -jar "target/datalog/datalog.jar"
Children of Zeus = Apollo :: Ares :: Nil
Ancestors of Apollo = Kronos :: Leto :: Rhea :: Zeus :: Nil
0

effects 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
    |       effects.flix
    \---test
            effectsTest.flix

Command gradle-q run – given the configuration build.gradle (resp. common.gradle) – generates and executes the target file target\effects\effects.jar :

> gradle -q run
2

1
2
3
4

2
4
6
8
0

interop 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
    |       interop.flix
    \---test
            interopTest.flix

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

> build run
false
0

mutualrecursion 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
    |       mutualrecursion.flix
    |       MutualRecursion.java
    \---test
            mutualrecursionTest.flix

Command make-s run – given the configuration Makefile (resp. Makefile.inc) – generates and executes the target file target\mutualrecursion\mutualrecursion.jar :

> make -s run
true
0

🔎 Command build.bat features option -java to compile/run the Java version of this code example.

> build -java -verbose run
Compile Java source files to directory "target\classes"
Execute Java program "MutualRecursion"
true

random 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
    |       random.flix
    \---test
            randomTest.flix

Command gradle-q run – given the configuration build.gradle (resp. common.gradle) – generates and executes the target file target\random\random.jar :

> gradle -q run
109
169
[...]
192
124
0

tailcalls 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
    |       tailcalls.flix
    |       tailcalls.java
    \---test
            tailcallsTest.flix

Command build.batrun builds and generates the target file target\tailcalls\tailcalls.jar :

> build run
312512500
0

🔎 The same example written in Java (src\main\tailcalls.java) fails with a runtime error :

> build -java run
Exception in thread "main" java.lang.StackOverflowError
        at Tailcalls.tailsum(tailcalls.java:12)
        at Tailcalls.tailsum(tailcalls.java:12)
        [...]
        at Tailcalls.tailsum(tailcalls.java:12)
        at Tailcalls.tailsum(tailcalls.java:12)
Error: Failed to execute Java program "Tailcalls"

Footnotes▴

[1] Updated source files ↩

Here are our modifications of the original Flix code examples from Lutz Hühnken's article "Flix for Java programmers" (June 2022) :

Source file(s)	Source code change
*.flix	Old syntax: & Impure, new syntax: \ IO.
channels.flix random.flix	Changed return type Unit & Impure to Unit \ NonDet for functions doSomething and main (see definition of Random.nextInt64).

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mics/January 2025 ▲