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

3. ★ ★ ★ ★
5. // This is a comment
6. name = “David McKay” age = 1.2 alive = true
7. name = “David McKay” objects = {name, age: 23}
8. durationLiteral = 1mo7d timeLiterals = 2018-08-28T10:20:00Z = 2018-08-28 dateMath = 2019-01-01 + 1mo3d
9. square = (n) => n * n tweet(at: “rawkode”, message: “Sweet!”)
10. moveIn() |> moveOut() |> handsUp() |> handsDown() |> backUp() |> backUp() |> roll()
11. > ʭ = () => "I don't know what this symbol is called" > ʭ () -> string > ʭ() I don't know what this symbol is called
12. > hotdog = () => “Armour !” > hotdog() > Armour ! > = () => “Armour Hotdog!” Error: invalid statement @1:1-1:5:
14. package rawkode gitHubHandle = “rawkode” hello = () => "Hello" awesomeThings = ["BBQ", "Hot Sauce", “”]
15. package rawkode awesomeise = (table=<-) => { table |> map(fn: (r) => "Awesome" + r) }
16. rawkode@penguin:~ ./flux repl > @rawkode.flux > awesomeThings |> awesomeise
19. ➔ ➔ ➔ ➔ ➔ ➔ ➔ ➔
20. import "math" math.NaN() // Returns NaN
21. import "math" math.sqrt(x: 4.0) // Returns 2.0
22. import "strings" strings.title(v: "a flux of foxes") // returns "A Flux Of Foxes"
23. import "csv" csv.from(file: "/path/to/data-file.csv") // OR csv.from(csv: csvData)
24. import "testing" testing.assertEquals( name: "streamEquality", got: got, want: want )
26. ★ ★ ◦ ◦ ◦ ◦ ★
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30. package math // builtin constants builtin pi // builtin functions builtin abs
31. package math func init() { // constants flux.RegisterPackageValue("math", "pi", values.NewFloat(math.Pi)) }
33. "github.com/influxdata/flux/values"
34. package math func init() { // constants flux.RegisterPackageValue("math", "pi", values.NewFloat(math.Pi)) }
35. package math func init() { // rand function flux.RegisterPackageValue( values.NewFunction(“math”, ???) ) }
36. ★ ◦ ◦ ◦ ◦
37. values.NewFunction( "rand", ???, ???, ??? )
38. // rand with no params semantic.NewFunctionPolyType(semantic.FunctionPolySignature{ Parameters: map[string]semantic.PolyType{}, Return: semantic.UInt, }), // in Go: func rand() uint
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
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
41. values.NewFunction( "rand", semantic.NewFunctionPolyType( … ) ???, ??? )
42. // No Error Checking func() (values.Value, error) { goRand := rand.New(rand.NewSource(...)) return values.NewFloat(goRand.Intn(100)), nil }
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() ) }
44. values.NewFunction( "rand", semantic.NewFunctionPolyType( … ) func(args values.Object) (values.Value, error){ … }, ??? )
46. values.NewFunction( "rand", semantic.NewFunctionPolyType( … ) func(args values.Object) (values.Value, error){ … }, false )
48. Compilation !== Unit Test
49. expected = goRand.Intn(100)
50. fluxFn = values.NewFunction(...) fluxArg := values.NewObjectWithValues( map[string]values.Value{ "max": values.NewFloat(100) } ) result, err := fluxFn.Call(fluxArg)
63. 1. 2. 3.
65. Thank You