Developing Your Own Flux Packages (InfluxDays London 2019)

Flux is easy to contribute to, and it is easy to share functions and libraries of Flux code with other developers. Although there are many functions in the language, the true power of Flux is its ability to be extended with custom functions. In this session, David will show you how to write your own custom function to perform some new analytics.

Transcript

1. View Slide

2. View Slide

3. ★
   ★
   ★
   ★
   

   View Slide

4. View Slide

5. // This is a comment
   

   View Slide

6. name = “David McKay”
   age = 1.2
   alive = true
   

   View Slide

7. name = “David McKay”
   objects = {name, age: 23}
   

   View Slide

8. durationLiteral = 1mo7d
   timeLiterals = 2018-08-28T10:20:00Z
   = 2018-08-28
   dateMath = 2019-01-01 + 1mo3d
   

   View Slide

9. square = (n) => n * n
   tweet(at: “rawkode”, message: “Sweet!”)
   

   View Slide

10. moveIn()
    |> moveOut()
    |> handsUp()
    |> handsDown()
    |> backUp()
    |> backUp()
    |> roll()
    

    View Slide

11. > ʭ = () => "I don't know what this symbol is called"
    > ʭ
    () -> string
    > ʭ()
    I don't know what this symbol is called
    

    View Slide

12. > hotdog = () => “Armour !”
    > hotdog()
    > Armour !
    > = () => “Armour Hotdog!”
    Error: invalid statement @1:1-1:5:
    

    View Slide

13. View Slide

14. package rawkode
    gitHubHandle = “rawkode”
    hello = () => "Hello"
    awesomeThings = ["BBQ", "Hot Sauce", “”]
    

    View Slide

15. package rawkode
    awesomeise = (table= {
    table |> map(fn: (r) => "Awesome" + r)
    }
    

    View Slide

16. rawkode@penguin:~ ./flux repl
    > @rawkode.flux
    > awesomeThings |> awesomeise
    

    View Slide

17. View Slide

18. View Slide

19. ➔
    ➔
    ➔
    ➔
    ➔
    ➔
    ➔
    ➔
    

    View Slide

20. import "math"
    math.NaN()
    // Returns NaN
    

    View Slide

21. import "math"
    math.sqrt(x: 4.0)
    // Returns 2.0
    

    View Slide

22. import "strings"
    strings.title(v: "a flux of foxes")
    // returns "A Flux Of Foxes"
    

    View Slide

23. import "csv"
    csv.from(file: "/path/to/data-file.csv")
    // OR
    csv.from(csv: csvData)
    

    View Slide

24. import "testing"
    testing.assertEquals(
    name: "streamEquality",
    got: got,
    want: want
    )
    

    View Slide

25. View Slide

26. ★
    ★
    ○
    ○
    ○
    ○
    ★
    

    View Slide

27. ★
    ★
    ★
    

    View Slide

28. View Slide

29. View Slide

30. package math
    // builtin constants
    builtin pi
    // builtin functions
    builtin abs
    

    View Slide

31. package math
    func init() {
    // constants
    flux.RegisterPackageValue("math", "pi",
    values.NewFloat(math.Pi))
    }
    

    View Slide

32. View Slide

33. "github.com/influxdata/flux/values"
    

    View Slide

34. package math
    func init() {
    // constants
    flux.RegisterPackageValue("math", "pi",
    values.NewFloat(math.Pi))
    }
    

    View Slide

35. package math
    func init() {
    // rand function
    flux.RegisterPackageValue(
    values.NewFunction(“math”, ???)
    )
    }
    

    View Slide

36. ★
    ○
    ○
    ○
    ○
    

    View Slide

37. values.NewFunction(
    "rand",
    ???,
    ???,
    ???
    )
    

    View Slide

38. // rand with no params
    semantic.NewFunctionPolyType(semantic.FunctionPolySignature{
    Parameters: map[string]semantic.PolyType{},
    Return: semantic.UInt,
    }),
    // in Go: func rand() uint
    

    View Slide

39. // rand with 1 param: max
    semantic.NewFunctionPolyType(semantic.FunctionPolySignature{
    Parameters: map[string]semantic.PolyType{
    "max": semantic.UInt
    },
    Required: semantic.LabelSet{"max"},
    Return: semantic.UInt,
    }),
    // in Go: func rand(max uint) uint
    

    View Slide

40. // rand with 2 param: min, max
    semantic.NewFunctionPolyType(semantic.FunctionPolySignature{
    Parameters: map[string]semantic.PolyType{
    "min": semantic.UInt,
    "max": semantic.UInt
    },
    Required: semantic.LabelSet{"min", "max"},
    Return: semantic.UInt,
    }),
    // in Go: func rand(min uint, max uint) uint
    

    View Slide

41. values.NewFunction(
    "rand",
    semantic.NewFunctionPolyType( … )
    ???,
    ???
    )
    

    View Slide

42. // No Error Checking
    func() (values.Value, error) {
    goRand := rand.New(rand.NewSource(...))
    return values.NewFloat(goRand.Intn(100)), nil
    }
    

    View Slide

43. func(args values.Object) (values.Value, error) {
    max, ok := args.Get("max")
    if !ok {
    return nil, errors.New("missing argument max")
    }
    if max.Type().Nature() == semantic.UInt {
    goRand := rand.New(rand.NewSource(time.Now().UnixNano()))
    return values.NewFloat(goRand.Intn(max.UInt())), nil
    }
    return nil, fmt.Errorf(
    "cannot convert argument of type %v to uint",
    v.Type().Nature()
    )
    }
    

    View Slide

44. values.NewFunction(
    "rand",
    semantic.NewFunctionPolyType( … )
    func(args values.Object) (values.Value, error){ … },
    ???
    )
    

    View Slide

45. View Slide

46. 
    values.NewFunction(
    "rand",
    semantic.NewFunctionPolyType( … )
    func(args values.Object) (values.Value, error){ … },
    false
    )
    

    View Slide

47. View Slide

48. Compilation !== Unit Test
    

    View Slide

49. expected = goRand.Intn(100)
    

    View Slide

50. fluxFn = values.NewFunction(...)
    fluxArg := values.NewObjectWithValues(
    map[string]values.Value{
    "max": values.NewFloat(100)
    }
    )
    result, err := fluxFn.Call(fluxArg)
    

    View Slide

51. View Slide

52. View Slide

53. View Slide

54. View Slide

55. View Slide

56. View Slide

57. View Slide

58. View Slide

59. View Slide

60. View Slide

61. View Slide

62. View Slide

63. 1.
    2.
    3.
    

    View Slide

64. View Slide

65. Thank You
    

    View Slide