Oden – A Functional Programming Language for the Go Ecosystem (PolyConf 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)
2. Agenda • Background • Project Goals • Current State • What’s next? • Questions
3. Background
4. Things I’ve been thinking about lately
5. I want type-safe functional programming for writing servers.
6. Haskell is a great language.
7. Can we have the safety of Haskell, but in a smaller and simpler language?
8. Do I really need interactive development? How much complexity does the REPL bring?
9. We should optimize for writing code that is correct, readable, and safe to change.
10. We should not optimize for cleverness.
11. Maybe static typing on top of Javascript?
12. Having to write FFI bindings to use libraries is cumbersome. Can the compiler do this for us?
13. Can we reuse all the good stuff from Go, but use a functional language?
14. Yes, we can!
15. Why Go? • Ecosystem of libraries and tools • Goroutines, channels • Cross-compilation • Static linking • Simple compile target • Fast compiler
16. What I’m missing in Go
17. Expressions over statements
18. Generic Programming
19. Abstraction
20. 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 }
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 }
22. if err ! nil { return err }
23. ... f, err : os.Create(localTarget) if err ! nil { return err } io.Copy(f, res.Body) if err ! nil { return err } return nil }
24. Project Goals
25. Use Go as a platform
26. Avoid cleverness, prefer clarity
27. Expressions over statements
28. Support generic programming
29. Support good abstractions
30. Type inference
31. Immutability by default
32. Pattern matching
33. Exhaustiveness checking
34. Simple interoperability with Go
35. Fun!
36. Open-source from the beginning
37. Figure: MVP Pyramid
38. Current State
39. Hello World package main main() println("Hello World")
40. Operators - * / ( - ) / * ( ) ! "Foo" "Bar" false && (true || ( ))
41. Operator Desugaring Operator Protocol Method - Num Negate ! Logical Not Num Add - Num Subtract * Num Multiply / Num Divide && Logical Conjunction || Logical Disjunction Monoid Apply
42. No custom operators
43. Curried Functions plus(x, y) x y twice(f, x) f(f(x)) plusTwenty twice(plus( )) forty plusTwenty( )
44. 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( )
45. Imports from Go package main import html main() { println(html.EscapeString("Simon & Garfunkel")) // Simon & Garfunkel }
46. Records sweden { official "Kingdom Of Sweden", population , capital "Stockholm" } usa { official "United States of America", population , capital "Washington D.C." }
47. Record Types sweden : { official : string, population : int, capital : string }
48. Records and Row Polymorphism fullName(person) person.firstName " " person.lastName
49. Records and Row Polymorphism fullName : forall r. { firstName : string, lastName : string | r } - string
50. Protocols Spoiler: Very similar to type classes
51. Protocols impl Monoid({ x: int, y: int }) { Apply(p , p ) { x p .x p .x, y p .y p .y } Identity { x , y } }
52. Protocols position { x , y } distance { x , y } target Monoid::Apply(position, distance)
53. Protocols position { x , y } distance { x , y } target position distance
54. Finding more information
55. oden-lang.org
56. oden-lang.org/user-guide/latest/
57. playground.oden-lang.org
58. @odenlang
59. What’s next?
60. Thank you!