What is ReasonML?

Transcript

1. What is ReasonML?
   Munich, 2018-02-01
   

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2. ReasonML
   • A new programming language by Facebook.
   • Supports several styles:
   • Functional programming
   • Imperative programming
   • Object-oriented programming
   In a nutshell: different syntax for OCaml
   

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3. OCaml syntax
   (.ml, .mli)
   ReasonML syntax
   (.re, .rei)
   OCaml AST
   Bytecode Native code JavaScript
   BuckleScript
   ocamlopt
   ocamlc
   ReasonML inside the OCaml ecosystem
   

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4. type tree = Leaf | Node(int, tree, tree);
   let rec sum = (x) =>
   switch (x) {
   | Leaf => 0
   | Node(value, left, right) =>
   value + sum(left) + sum(right);
   };
   let myTree =
   Node(
   1,
   Node(2, Node(4, Leaf, Leaf),
   Node(6, Leaf, Leaf)),
   Node(3, Node(5, Leaf, Leaf),
   Node(7, Leaf, Leaf))
   );
   sum(myTree) |> print_int;
   • Syntax: JS
   • Style: FP
   • No type annotations

   (x, myTree)
   

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5. Dr. Axel Rauschmayer, @rauschma
   Foundation: OCaml
   • Proven in the real world
   • Created in 1996 at INRIA (France)
   • Used at Facebook, Bloomberg, Jane Street, etc.
   • An object-functional language.
   • Supports mutable state (as an “escape hatch”).
   • Compiles to bytecode, native code, good-looking JavaScript
   • Building JavaScript is fast
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6. Dr. Axel Rauschmayer, @rauschma
   Focus of ReasonML
   • Tooling (IDE support etc.)
   • Interoperability with JavaScript
   • React (built-in syntax etc.)
   • Better standard library
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7. Dr. Axel Rauschmayer, @rauschma
   Future
   Current weaknesses:
   • Better support for JS Promises
   • Better standard library (currently not always cross-platform)
   • Better support for Unicode (currently not cross-platform)
   • Better support for overloading (ad-hoc polymorphism)
   • No more + vs. +.
   • Similar to Haskell’s type classes
   • Truly native React Native
   • Long term: multicore
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8. Dr. Axel Rauschmayer, @rauschma
   ReasonReact
   • Batteries included:
   • Router
   • Redux
   • Typed support for GraphQL via graphql_ppx
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9. Dr. Axel Rauschmayer, @rauschma
   Tips for getting started
   • Try out quickly:
   • Interactive command line (offline): rtop
   • Online playground
   • Write sync Node.js-based shell scripts
   • Generate template projects. E.g.:

   bsb -init my-first-app -theme basic-reason
   • Visual Studio Code
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10. Dr. Axel Rauschmayer, @rauschma
    Documentation
    • Online docs. Well-written!
    • Material on OCaml
    • Convert OCaml ↔ ReasonML: refmt,
    playground
    • 2ality.com/2017/11/about-reasonml.html
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