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Dex Test status

Dex (named for "index") is a research language for typed, functional array processing. The goal of the project is to explore:

  • Type systems for array programming
  • Mathematical program transformations like differentiation and integration
  • User-directed compilation to parallel hardware
  • Interactive and incremental numerical programming and visualization

To learn more, check out our paper, our tutorial or these example programs:

Or for a more comprehensive look, there's

  • The InDex of all documents, libraries, and examples included in this repository.

🚨 Dex is an experimental research project at an early stage of development. Expect monstrous bugs and razor-sharp edges!

🤝 Contributions welcome! See our issue tracker for good first issues, or browse by thematic labels.


  • Install stack
  • Install LLVM 12
    • Ubuntu/Debian: apt-get install llvm-12-dev
    • macOS: brew install llvm@12
      • Make sure llvm@12 is on your PATH before building. Example: export PATH="$(brew --prefix llvm@12)/bin:$PATH"
  • Install clang 12 (may be installed together with llvm)
    • Ubuntu/Debian: apt-get install clang-12
    • macOS: installs with llvm
  • Install libpng (often included by default in *nix platforms)
    • Ubuntu/Debian: apt-get install libpng-dev
    • macOS: brew install libpng


To build and install a release version of Dex run make install.

The default installation directory is $HOME/.local/bin, so make sure to add that directory to $PATH after installing Dex. To install Dex somewhere else, set the PREFIX environment variable before running make install. For example, PREFIX=$HOME make install installs dex in $HOME/bin.


  • Build Dex in development (unoptimized) mode: make
  • Run tests in development mode: make tests

It is convenient to set up a dex alias (e.g. in .bashrc) for running Dex in development mode:

# Linux:
alias dex="stack exec dex -- --lib-path lib"

# macOS:
alias dex="stack exec --stack-yaml=stack-macos.yaml dex -- --lib-path lib"

You might also want to consider other development build targets:

  • build-opt for local optimized builds,
  • build-dbg for local debug builds,
  • build-prof for local optimized builds with profiling enabled.

Those non-standard targets require different aliases. Please consult the documentation at the top of the makefile for detailed instructions.

Haskell Language Server

In order to use HLS with the Haskell code in this project:

  • Install ghcup
  • Run ghcup install hls
  • Create a file in the root dex directory called hie.yaml with the following contents:
    stackYaml: "./stack-macos.yaml"  # Or stack.yaml if not on MacOS

Unfortunately one cannot dynamically select the stack.yaml file to use based on the environment, and so one has to create an appropriate hie.yaml file manually. This will be ignored by git.

This should work out of the box with Emacs' lsp-haskell package.

Building with Nix

Nix is a functional package manager and build system.

To build with vanilla Nix:

$ nix-build

To build with flakes-enabled Nix:

$ nix build .#dex

The resulting dex binary should be in result/bin/dex.

For development purposes, you can use a Nix environment with

$ nix-shell
$ nix develop  # With flakes

and use make to use Stack to build Dex.


  • Traditional REPL: dex repl
  • Execute script: dex script examples/pi.dx
  • Live-updated notebook display dex web examples/pi.dx (html) or dex watch examples/pi.dx (terminal).



This is an early-stage research project, not an official Google product.


Research language for array processing in the Haskell/ML family







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