Oden – A Functional Programming Language for the Go Ecosystem (Curry On 2016)

This talk will introduce Oden, an experimental, statically typed, functional programming language built for the Go ecosystem. We will look at how Oden aims to leverage the great features of Go — static linking, cross-compilation, goroutines, channels and the great set of libraries and tools — and enable higher-level abstractions, generics and a safer yet more flexible type system.

Transcript

1. Oden
   A Functional Programming Language
   for the Go Ecosystem
   Oskar Wickström
   @owickstrom
   

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2. http://empear.com
   @owickstrom
   

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3. Agenda
   • Background
   • Project Goals
   • Current State
   • What’s next?
   • Questions
   @owickstrom
   

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4. Background
   @owickstrom
   

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5. Things I’ve been thinking about lately
   @owickstrom
   

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6. I want type-safe functional programming for
   writing web applications.
   @owickstrom
   

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7. Haskell is a great language.
   @owickstrom
   

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8. Can we have the safety of Haskell, but in a
   smaller and simpler language?
   @owickstrom
   

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9. I want fast, "clean slate" compilation as an option.
   @owickstrom
   

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10. We should optimize for writing code that is
    correct, understandable, and safe to change.
    @owickstrom
    

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11. We should not optimize for cleverness.
    @owickstrom
    

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12. Maybe static typing on top of Javascript?
    @owickstrom
    

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13. Having to write FFI bindings to use libraries is
    cumbersome. Can the compiler do this for us?
    @owickstrom
    

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14. Can we reuse all the good stuff from Go, but use a
    functional language?
    @owickstrom
    

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15. Yes, we can!
    @owickstrom
    

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16. Why Go?
    • Ecosystem of libraries and tools
    • Goroutines, channels
    • Cross-compilation
    • Static linking
    • Simple compile target
    • Fast compiler
    @owickstrom
    

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17. What I’m missing in Go
    @owickstrom
    

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18. Expressions over statements
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19. Generic Programming
    @owickstrom
    

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20. Abstraction
    @owickstrom
    

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21. func (c *dropboxClient) GetFile(accessToken, dropboxSrc, localTarget string) error {
    url : "https://content.dropboxapi.com/ /files/auto" dropboxSrc
    req, err : http.NewRequest("GET", url, nil)
    req.Header.Add("Authorization", "Bearer " accessToken)
    if err ! nil {
    return err
    }
    client : &http.Client{}
    res, err : client.Do(req)
    if err ! nil {
    return err
    }
    if res.StatusCode {
    return ErrNotFound
    }
    if res.StatusCode || res.StatusCode {
    return errors.New("Dropbox request failed: " res.Status)
    }
    f, err : os.Create(localTarget)
    if err ! nil {
    return err
    }
    io.Copy(f, res.Body)
    if err ! nil {
    return err
    }
    return nil
    }
    @owickstrom
    

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22. func (c *dropboxClient) GetFile(accessToken, dropboxSrc, localTarget string) error {
    url : "https://content.dropboxapi.com/ /files/auto" dropboxSrc
    req, err : http.NewRequest("GET", url, nil)
    req.Header.Add("Authorization", "Bearer " accessToken)
    if err ! nil {
    return err
    }
    client : &http.Client{}
    res, err : client.Do(req)
    if err ! nil {
    return err
    }
    if res.StatusCode {
    return ErrNotFound
    }
    if res.StatusCode || res.StatusCode {
    return errors.New("Dropbox request failed: " res.Status)
    }
    f, err : os.Create(localTarget)
    if err ! nil {
    return err
    }
    io.Copy(f, res.Body)
    if err ! nil {
    return err
    }
    return nil
    }
    @owickstrom
    

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23. if err ! nil {
    return err
    }
    @owickstrom
    

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24. ...
    f, err : os.Create(localTarget)
    if err ! nil {
    return err
    }
    io.Copy(f, res.Body)
    if err ! nil {
    return err
    }
    return nil
    }
    @owickstrom
    

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25. Project Goals
    @owickstrom
    

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26. Use Go as a platform
    @owickstrom
    

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27. Avoid cleverness, prefer clarity
    @owickstrom
    

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28. Expressions over statements
    @owickstrom
    

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29. Support generic programming
    @owickstrom
    

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30. Support good abstractions
    @owickstrom
    

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31. Type inference
    @owickstrom
    

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32. Immutability by default
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33. Pattern matching
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34. Exhaustiveness checking
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35. Simple interoperability with Go
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36. Fun!
    @owickstrom
    

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37. Open-source from the beginning
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38. Figure: MVP Pyramid
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39. Current State
    @owickstrom
    

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40. Hello World
    package main
    main() println("Hello World")
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41. Operators
    !true
    -
    *
    /
    ( - ) /
    * -( )
    !
    "Foo" "Bar"
    false && (true || ( ))
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42. Operator Desugaring
    Operator Protocol Method
    - Num Negate
    ! Logical Not
    Num Add
    - Num Subtract
    * Num Multiply
    / Num Divide
    && Logical Conjunction
    || Logical Disjunction
    Monoid Apply
    @owickstrom
    

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43. No custom operators
    @owickstrom
    

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44. No macros
    @owickstrom
    

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45. Curried Functions
    plus(x, y) x y
    twice(f, x) f(f(x))
    plusTwenty twice(plus( ))
    forty plusTwenty( )
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46. Curried Functions with Type Signatures
    plus : int - int - int
    plus(x, y) x y
    twice : forall a. (a - a) - a - a
    twice(f, x) f(f(x))
    plusTwenty : int - int
    plusTwenty twice(plus( ))
    forty : int
    forty plusTwenty( )
    @owickstrom
    

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47. Imports from Go
    package main
    import html
    main() {
    println(html.EscapeString("Simon & Garfunkel"))
    // Simon & Garfunkel
    }
    @owickstrom
    

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48. Imports from Go
    package main
    import foreign "html"
    main() {
    println(html.EscapeString("Simon & Garfunkel"))
    // Simon & Garfunkel
    }
    @owickstrom
    

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49. Records
    sweden {
    official "Kingdom Of Sweden",
    population ,
    capital "Stockholm"
    }
    usa {
    official "United States of America",
    population ,
    capital "Washington D.C."
    }
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50. Record Types
    sweden : {
    official : string,
    population : int,
    capital : string
    }
    @owickstrom
    

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51. Records and Row Polymorphism
    fullName(person)
    person.firstName " " person.lastName
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52. Records and Row Polymorphism
    fullName : forall r.
    {
    firstName : string,
    lastName : string
    | r
    }
    - string
    @owickstrom
    

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53. Protocols
    Spoiler: Very similar to type classes
    @owickstrom
    

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54. Protocols
    impl Monoid({ x: int, y: int }) {
    Apply(p , p ) {
    x p .x p .x,
    y p .y p .y
    }
    Identity { x , y }
    }
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55. Protocols
    position { x , y }
    distance { x , y }
    target Monoid::Apply(position, distance)
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56. Protocols
    position { x , y }
    distance { x , y }
    target position distance
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57. Procotols are not simple
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58. That’s not all
    @owickstrom
    

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59. Finding more information
    @owickstrom
    

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60. oden-lang.org
    @owickstrom
    

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61. oden-lang.org/user-guide/latest/
    @owickstrom
    

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62. playground.oden-lang.org
    @owickstrom
    

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63. @odenlang
    @owickstrom
    

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64. What’s next?
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65. Thank you!
    @owickstrom
    

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