Elchemy Report

- erlang (1985) strong / dynamic types

- elixir (2011) strong / dynamic types

- [other 20+](https://github.com/llaisdy/beam_languages) dead or alive **dynamic** typed languages

]

---

.right-column.center[
  ##### Dynamic typing is ...
]

---

.right-column.center[
  ##### Dynamic typing is pain
  <img src="img/dynamic-typing-meme.jpeg" width="88%">
]

---

- founded by [Christopher Wende](https://github.com/wende)

- since 2017

- subset of elm (haskell)

- Hindley–Milner type system (type inference etc)

- generates readable elixir source code

]

---

.center[
  ### [Concept](https://github.com/tim2CF/elchemy_poker) of poker game engine
  #### reasons
]

- Elm (Haskell) is good to build pure business logic

- Elchemy officialy not support side-effects

- Cannot use enterprise OTP / Phoenix / Ecto stuff

<br><br>
.center[
  So, we can say that Elchemy is good to write safe solid pieces of pure business logic. Pure functions without side-effects like this task.
]

]

---

- It's [easy](https://github.com/wende/elchemy/blob/4112523266c245a10a7aad987753241eb97074a5/README.md#troubleshooting) to use Elchemy inside existing Elixir codebase

- Natural representation of types / business models
  - [example 1](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/elm/elchemyPoker/models/Card.elm#L4-L7)
  - [example 2](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/elm/elchemyPoker/models/Combo.elm#L5-L16)

- **STRONG STATIC types**

- 100% safe runtime inside Elchemy - generated code

- It's not possible to throw [exception](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/elm/elchemyPoker/models/Combo.elm#L28-L29)

- No any implicit [stuff](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/elm/elchemyPoker/models/Combo.elm#L33)

- No needed FFI to call from Elixir

- [Simple](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/elm/elchemyPoker/Utils.elm#L7) FFI for Elixir calls from Elchemy

- Auto generated Elixir [specs](https://github.com/tim2CF/elchemy_poker/blob/6f975bfd0b6c3ca20a507ade19a83a9027ad7817/lib/elchemy_poker/Utils.elchemy.ex#L43) (for Dialyzer and kind of documentation)

]

---

- Meta programming is not supported

- No OTP / Phoenix / Ecto enterprise goodies (yet?)

- Maintained by only one [person](https://github.com/wende/elchemy/issues)

- Haskell-like currying in [generated code](https://wende.github.io/elchemy-ivy/calling-elchemy.html)

- In some cases performance is slower up to 15%

- FFI calls are not 100% safe (up to developer)

]

---

.left-column[
### BEAM langs
### Elchemy
### Experiment
### Advantages
### Disadvantages
### Results
]

- Elchemy compiler is pretty raw

- Concept was not completed because of compiler issues
  - [type aliases](https://github.com/wende/elchemy/issues/245)
  - [source code naming policy](https://github.com/wende/elchemy/issues/246)
  - [Elm case to Elixir function clause](https://github.com/wende/elchemy/issues/247)
  - [type aliases representation in Elixir](https://github.com/wende/elchemy/issues/251)
  - [excess of currying in generated Elixir source code](https://github.com/wende/elchemy/issues/218)

- Christopher is very responsive guy, he fixed almost all issues and released new 0.5.4 version of Elchemy compiler **in 1 day**!

- Christopher needs your (as user and developer) help to improve compiler

- Elchemy compiler still looks very perspective

- It's good opportunity for Elixir developers to learn Elm

- Maybe it's nice to have a look to other static-typed BEAM language [Alpaca](https://github.com/alpaca-lang)

]

---

# Thanks