Jou programming language
Jou is an experimental toy programming language. It looks like this:
import "stdlib/io.jou"
def main() -> int:
puts("Hello World")
return 0
See the examples and tests directories for more example programs
or read the Jou tutorial.
So far, Jou is usable for writing small programs that don't have a lot of dependencies.
For example, I solved all problems of Advent of Code 2023 in Jou.
See examples/aoc2023 for the code.
Goals:
- Minimalistic feel of C + simple Python-style syntax
- Possible target audiences:
- People who find C programming fun
- Python programmers who want to try programming at a lower level (maybe to eventually learn C or Rust)
- Compatibility with C, not just as one more feature but as the recommended way to do many things
- Self-hosted compiler
- Eliminate some stupid things in C. For example:
- Many useful warnings being disabled by default
- UB for comparing pointers into different memory areas
(as in
array <= foo && foo < array+sizeof(array)/sizeof(array[0])
)
negative % positive
is negative or zero, should IMO be positive or zero
(unless that is a lot slower, of course)
- Strict aliasing
int
possibly being only 16 bits
long
possibly being only 32 bits
char
possibly being more than 8 bits
char
possibly being signed
char
being named char
even though it's really a byte
- Generics, so that you can implement a generic
list
(dynamically growing array)
better than in C
- Compiler errors for most common bugs in C (missing
free()
, double free()
, use after free, etc.)
- More keywords (
def
, decl
, forwarddecl
)
- Enumerated unions = C
union
together with a C enum
to tell which union member is active
- Windows support that doesn't suck
Non-goals:
- Yet another big language that doesn't feel at all like C (C++, Zig, Rust, ...)
- Garbage collection (should feel lower level than that)
- Wrapper functions for the C standard library
- Wrapper libraries for existing C libraries (should just use the C library directly)
- Trying to detect every possible memory bug at compile time
(Rust already does it better than I can, and even then it can be painful to use)
- Copying Python's gotchas
(e.g. complicated import system with weird syntax and much more weird runtime behavior)
Setup
These instructions are for using Jou.
The instructions for developing Jou are in CONTRIBUTING.md.
Linux
1. Install the dependencies:
```
$ sudo apt install git llvm-14-dev clang-14 make
```
Let me know if you use a distro that doesn't have `apt`,
and you need help with this step.
2. Download and compile Jou.
```
$ git clone https://github.com/Akuli/jou
$ cd jou
$ make
```
3. Run the hello world program to make sure that Jou works:
```
$ ./jou examples/hello.jou
Hello World
```
You can now run other Jou programs in the same way.
4. (Optional) If you want to run Jou programs with simply `jou filename`
instead of something like `./jou filename` or `/full/path/to/jou filename`,
you can add the `jou` directory to your PATH.
To do so, edit `~/.bashrc` (or whatever other file you have instead, e.g. `~/.zshrc`):
```
$ nano ~/.bashrc
```
Add the following line to the end:
```
export PATH="$PATH:/home/yourname/jou/"
```
Replace `/home/yourname/jou/` with the path to the folder (not the executable file) where you downloaded Jou.
Note that the `~` character does not work here,
so you need to use a full path (or `$HOME`) instead.
These LLVM/clang versions are supported:
- LLVM 11 with clang 11
- LLVM 13 with clang 13
- LLVM 14 with clang 14
By default, the `make` command picks the latest available version.
You can also specify the version manually by setting the `LLVM_CONFIG` variable:
```
$ sudo apt install llvm-11-dev clang-11
$ make clean # Delete files that were compiled with previous LLVM version
$ LLVM_CONFIG=llvm-config-11 make
```
MacOS
MacOS support is new. Please create an issue if something doesn't work.
1. Install Git, make and LLVM 13.
If you do software development on MacOS, you probably already have Git and make,
because they come with Xcode Command Line Tools.
You can use [brew](https://brew.sh/) to install LLVM 13:
```
$ brew install llvm@13
```
2. Download and compile Jou.
```
$ git clone https://github.com/Akuli/jou
$ cd jou
$ make
```
3. Run the hello world program to make sure that Jou works:
```
$ ./jou examples/hello.jou
Hello World
```
You can now run other Jou programs in the same way.
4. (Optional) If you want to run Jou programs with simply `jou filename`
instead of something like `./jou filename` or `/full/path/to/jou filename`,
you can add the `jou` directory to your PATH.
To do so, edit `~/.bashrc` (or whatever other file you have instead, e.g. `~/.zshrc`):
```
$ nano ~/.bashrc
```
Add the following line to the end:
```
export PATH="$PATH:/Users/yourname/jou/"
```
Replace `/Users/yourname/jou/` with the path to the folder (not the executable file) where you downloaded Jou.
Note that the `~` character does not work here,
so you need to use a full path (or `$HOME`) instead.
NetBSD
Support for NetBSD is still experimental. Please report bugs and
shortcomings.
1. Install the dependencies:
```
# pkgin install bash clang git gmake libLLVM
```
Optionally `diffutils` can be installed for coloured diff outputs.
2. Download and compile Jou.
```
$ git clone https://github.com/Akuli/jou
$ cd jou
$ gmake
```
3. Run the hello world program to make sure that Jou works:
```
$ ./jou examples/hello.jou
Hello World
```
You can now run other Jou programs in the same way.
4. (Optional) If you want to run Jou programs with simply `jou
filename` instead of something like `./jou filename` or
`/full/path/to/jou filename`, you can add the `jou` directory to
your PATH. Refer to the manual page of your login shell for exact
syntax.
NB: Using Clang and LLVM libraries built as a part of the base system
is not currently supported.
64-bit Windows
1. Go to releases on GitHub. It's in the sidebar at right.
2. Choose a release (latest is probably good) and download a `.zip` file whose name starts with `jou_windows_64bit_`.
3. Extract the zip file somewhere on your computer.
4. You should now have a folder that contains `jou.exe`, lots of `.dll` files, and subfolders named `stdlib` and `mingw64`.
Add this folder to `PATH`.
If you don't know how to add a folder to `PATH`,
you can e.g. search "windows add to path" on youtube.
5. Write Jou code into a file and run `jou filename.jou` on a command prompt.
Try [the hello world program](examples/hello.jou), for example.
Updating to the latest version of Jou
Run jou --update
.
On old versions of Jou that don't have --update
,
you need to instead delete the folder where you installed Jou
and go through the setup instructions above again.
Editor support
Tell your editor to syntax-highlight .jou
files as if they were Python files.
You may want to copy some other Python settings too,
such as how to handle indentations and comments.
If your editor uses a langserver for Python,
make sure it doesn't use the same langserver for Jou.
For example, vscode uses the Pylance language server,
and you need to disable it for .jou
files;
otherwise you get lots of warnings whenever you edit
Jou code that would be invalid as Python code.
For example, I use the following configuration with the
Porcupine editor:
[Jou]
filename_patterns = ["*.jou"]
pygments_lexer = "pygments.lexers.Python3Lexer"
syntax_highlighter = "pygments"
comment_prefix = '#'
autoindent_regexes = {dedent = 'return( .+)?|break|pass|continue', indent = '.*:'}
To apply this configuration, copy/paste it to end of Porcupine's filetypes.toml
(menubar at top --> Settings --> Config Files --> Edit filetypes.toml).
How does the compiler work?
See CONTRIBUTING.md.