Please note that this language is work in progress.
hello_world is
# read someone's name from standard input
#
get_name String =>
match (io.stdin.with ()->
io.buffered.read_line ? str String => str | io.end_of_file => "")
name String => name
e error => panic "Could not get your name!"
# greet someone with the name given
#
greet(name String) is
say "Hello, {name}!"
# greet the user
#
x := greet get_name
# you can access any feature - even argument features of other features
# from outside
#
say "How are you, {x.name}?"
This hello_world example demonstrates one important concept in Fuzion quite
well: Everything is a feature. Features are Fuzion's response to the mess
that is created by classes, methods, interfaces, and various other
concepts in other programming languages. Since everything is a feature, the
programmer does not need to care and the compiler will do this work. As you can
see, it is even possible to access the argument features of some feature from
outside.
ex_gcd is
max(a, b i32) i32 =>
if a > b then a else b
common_divisors_of(a, b i32) list i32 =>
x := max a.abs b.abs
y := 1..x
y.flat_map i32 (i->
if (a % i = 0) && (b % i = 0)
[-i, i]
else
[])
.as_list
gcd(a, b i32) i32
pre
safety: (a != 0 || b != 0)
post
safety: a % result = 0
safety: b % result = 0
pedantic: (common_divisors_of a b).reduce bool true (tmp,cur->tmp && (gcd.this.result % cur = 0))
=>
if b = 0
a
else
gcd b (a % b)
say (gcd 8 12)
say (gcd -8 12)
say (gcd 28 0)
This example implements a simple variant of an algorithm that finds the greatest common divisor of two numbers. However, it also demonstrates one of Fuzion's notable features: design by contract. By specifying pre- and postconditions for features, correctness checks are made possible.
generator_effect is
# define a generator effect with a yield operation
#
gen(T type,
yield T->unit # yield is called by code to yield values
) : simple_effect is
# traverse a list and yield the elements
#
list.traverse unit =>
match list.this
c Cons => (generator_effect.gen A).env.yield c.head; c.tail.traverse
nil =>
# bind the yield operation dynamically
#
(gen i32 (i -> say "yielded $i")).use (()->
[0,8,15].as_list.traverse)
Another major concept in Fuzion is that of the algebraic effect - a new approach to encapsulating code with side effects in a safe way.
In the example above, a custom effect has been used to implement a generator
with a yield operation. In some other languages, this requires a keyword
yield to be provided by the language, but in Fuzion this can be implemented
without language support.
If you want to play around with Fuzion, try the interactive tutorial.
Check fuzion-lang.dev for language and implementation design.
Note that the current directory must not contain any spaces.
git clone https://github.com/tokiwa-software/fuzion
For Debian based systems this command should install all requirements:
sudo apt-get install make clang libgc1 libgc-dev openjdk-21-jdk
- OpenJDK 21, e.g. Adoptium
- clang LLVM C compiler
- GNU make
- libgc
This command should install all requirements:
brew install bdw-gc gnu-sed make temurin llvmAdditionally you may need to update your PATH environment variable e.g.:
export PATH:"/usr/local/opt/gnu-sed/libexec/gnubin:/usr/local/opt/gnu-make/libexec/gnubin:$PATH"
- OpenJDK 21, e.g. Adoptium
- clang LLVM C compiler
- GNU make
- libgc
Note that building from powershell/cmd does not work yet.
- Install chocolatey: chocolatey.org
- In Powershell:
- choco install git openjdk make msys2 diffutils
- [Environment]::SetEnvironmentVariable("Path","c:\tools\msys64\ucrt64\bin;" + $env:Path , "User")
- In file C:\tools\msys64\msys2_shell.cmd change line: 'rem set MSYS2_PATH_TYPE=inherit' to 'set MSYS2_PATH_TYPE=inherit'
- In msys2 shell (execute C:\tools\msys64\msys2_shell.cmd):
- pacman -S mingw-w64-x86_64-clang
- make
- execute ./bin/windows_install_boehm_gc.sh
Make sure java/javac and clang are in your $PATH.
cd fuzion
make
You should have a folder called build now.
cd build
export PATH=$PWD/bin:$PATH
cd tests/rosettacode_factors_of_an_integer
fz factors
To compile the same example (requires clang C compiler):
fz -c factors
./factors
Have fun!
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