npm install -g elchemy

Elchemy lets you write simple, fast and quality type safe code while leveraging both the Elm's safety and Elixir's ecosystem

• Type inference: Powerful type inference means you rarely have to annotate types. Everything gets checked for you by the compiler
• Easy and type-safe interop: You can call Elixir/Erlang without any extra boiler-plate. All the calls you make are checked in terms of type-safety as thoroughly as possible based on Elixir's typespecs.
• All the best of Elm and Elixir: Elchemy inherits what's best in Elm - type safety, inference and extreme expressiveness, but also what's best in Elixir - Doc-tests, tooling and obviously the entire BEAM platform.
• Nearly no runtime errors - Elchemy's type system eliminates almost all runtime errors. With a shrinking set of edge cases, your entire Elchemy codebase is safe. Elixir parts of the codebase are the only ones to be a suspect in cases of runtime errors happening.
• Beautiful and fully readable output - The produced code is idiomatic, performant and can be easily read and analyzed without taking a single look at the original source.

• Parser - 99% of Elm's syntax (see elm-ast)
• Compiler - 90% (Sophisticated incremental compilation. No support for Windows yet though (#287) and also big reliance on unix tools (#288)
• Elchemy-core - 95% ( Everything covered except side effects and JSON Decoders)
• Interop with Elixir - 90% - Purity tests (#162) and handling of macro-heavy libraries (#276) to go
• Ideology - 70% - We've got a pretty solid idea of where Elchemy is going
• Documentation - 80% - There are two tutorials and a complete Gitbook documentation. Few entrance level tutorials though, this project tries to change it.
• Elchemy-effects - 20% - You can't and shouldn't write anything with side-effects in Elchemy yet. We're working on finding the best solution for effects that would fit both Elm's and Elixir's community (see #297 for more info)
• Elchemy-core for Erlang VM - 5% - Everything for os related tasks like filesystem, OTP goodies etc are yet to be done
• Elchemy type checker - 20% - Self-hosted elchemy type inference algorithm, written by @wende and inspired by @Bogdanp.

• elixir@1.4.0-1.6.x
• node@5+
• elm-lang@0.18.0 (npm install -g elm@0.18.0)
• elm-github-install@0.1.2 - Compiler will install it automatically for you, if you don't have it yet.

Install elchemy globally with:

npm install -g elchemy

Then, in the root directory of your project do:

elchemy init

And follow the instructions.

elchemy will find all *.elm files specified in elchemy_path and compile it into corresponding *.ex files in lib directory.

You can override output directory specifying elixirc_paths.

npm install -g elchemy

Usage

elchemy compile source_dir output_dir

• Atom with elixir-language and atom-elixir or elixir-ide for Elixir; and language-elm + elmjutsu for Elchemy.
• Visual Studio Code with vscode-elixir, vscode-elixir-ls and vscode-elm

git clone https://github.com/wende/elchemy.git
cd elchemy
make compile
./elchemy compile source_dir output_dir

and

make dev

In order to launch and test the web demo.

If something doesn't work, try

npm install -g elchemy
elchemy clean
elchemy init
mix test

first

• You like types
• But even more you prefer compile-time errors over run-time error
• You prefer add b c = b + c over defp add(a, b), do: b + c
• You like curry
• You think failing fast is cool, but not as cool as not failing at all

• Your project relies on die-hard battle tested libraries, and you despise any versions starting with 0
• You're afraid that when you learn what Monad is your mustache will grow, and eyesight weaken

You can, but nice and dandy compile tools are still on their way

The output files of Elchemy treat the code readability as a first class citizen. The code is meant to be properly indented, the comments aren't omitted, and the code is optimized as hard as it can ( f.i case clauses reduce to function overloads)

Once it's done, so as it is supposed to be in the so called semantic versioning. 😇

Definitely. Yes. Please do. 💕

You're a nosy one, aren't you? 😄 Elchemy represents all type constructors as snake cased atoms, and all type applications as tuples. Which means that MyType 42 "Forty two" Error in Elchemy equals to {:my_type, 42, "Forty Two", :error} in Elixir.

As long as they don't use any Native modules, Ports or Elm runtime they can be safely imported and used

Yes. You can do an ffi call to any function in any module. Whether it's Elixir module, Erlang module, or even a macro you can include it in your code. Ffi calls are a treated specially in Elchemy, and they get generated test to analyze the types based on @specs, so that you don't compromise type safety for using Elixir code. In order to increase readability it's advised not to use ffi calls if not necessary and always document and doctest them.

Unfortunately you can't write any macros with do..end blocks yet. You can write any out of function code using an elixir inline code with:

{- ex
  *code_here*
-}

But it is a last resort solution and shouldn't ever be abused.

So you want to write an Elm-like code, that will manipulate Elixir code, which generates an Elixir code that manipulates Elixir code? How about no?

Elchemy uses Elm to typecheck your program. It is possible to use it without Elm on your machine, while it's not advised.

• Tomasz Cichociński - @baransu
• Colin Bankier - @colinbankier
• Nathaniel Knight - @neganp

• Elm by Evan Czaplicki - @evancz
• Elixir by José Valim - @josevalim
• Elm-AST by Bogdan Popa - @bogdanp

• Everyone is welcome to contribute 🤗
• Refer to https://bogdanp.github.io/elm-ast/example/ to have better understanding of parsed tokens.
• Refer to https://wende.github.io/elchemy/stable/ to know the latest development version of the parser
• For project management we use ZenHub. You can see the Kanban board, card estimates and all the reports by installing a browser extension here: Opera/Chrome, Firefox

• Fully readable and indented elixir code generated from compilation
• Seamless and stress less interop with existing Elixir code, preferably with magically working type safety
• Full integration with entire elm syntax for editors and compilers magic