Back to the future of JS

Slides form JSConf EU talk.

Transcript

1. Hallo!
   

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2. https://github.com/tc39/proposals
   

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4. @wmsbill
   What is this?
   

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5. @wmsbill
   this in the global scope
   Browser - window
   Web worker - self
   NodeJS - module.exports
   

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   this inside a function?
   

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7. @wmsbill
   this inside a function?
   

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9. @wmsbill
   How to make this predictable?
   Reasoning the value of this is tricky
   Function.prototype.bind
   Arrow function () => {}
   

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10. With .bind()
    

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11. With Arrow
    

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12. @wmsbill
    Calling a knowing function
    

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    Extracting a method from an object
    

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15. @wmsbill
    Two syntaxes
    Unary : :context.method()
    Binary context: :method()
    

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16. @wmsbill
    Binary syntax
    

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17. @wmsbill
    Unary syntax
    

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18. @wmsbill
    

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19. @wmsbill
    

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20. @wmsbill
    

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21. @wmsbill
    Bind operator is good for virtual
    methods
    But relies on this to be bound
    

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22. @wmsbill
    Composing without this
    

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23. @wmsbill
    

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24. @wmsbill
    

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26. @wmsbill
    Pipeline operator |>
    It is a syntax sugar for
    function composition
    It creates a way to streamline
    a chain of functions
    

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27. @wmsbill
    Pipeline operator |>
    

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28. @wmsbill
    

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29. @wmsbill
    

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30. @wmsbill
    

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31. @wmsbill
    Function with more params
    

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32. @wmsbill
    Function with more params
    

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33. @wmsbill
    Awaiting a function
    

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34. @wmsbill
    Awaiting a function
    

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35. @wmsbill
    Awaiting a function
    

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36. @wmsbill
    Awaiting a function
    

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37. @wmsbill
    Awaiting a function
    

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39. @wmsbill
    Smart pipeline
    

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40. @wmsbill
    Smart pipeline
    Two types bare style and topic style
    () or [] are disallowed in bare style
    When () or [] is needed, topic style
    is used
    # token is subject to change
    

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41. @wmsbill
    What about curry?
    

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42. @wmsbill
    F# pipeline proposal
    Extends the minimal proposal with
    an await step
    Await step waits for the resolution of
    the previous step
    

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43. @wmsbill
    F# pipeline proposal
    

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44. @wmsbill
    

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45. @wmsbill
    Partial application
    f(…) arity = n;
    partialapp(f(…)) arity = m;
    m < n
    

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46. @wmsbill
    

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47. @wmsbill
    

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48. @wmsbill
    Partial application in ES
    Achievable by
    Function.prototype.bind
    .bind() binds context and
    parameters
    

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49. @wmsbill
    

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50. @wmsbill
    What about currying?
    We can achieve partial application
    with curry
    Curry ≠ Partial application
    Curry returns arity n-1
    

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51. @wmsbill
    

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52. @wmsbill
    Partial application with arrow
    function
    

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54. @wmsbill
    Partial application proposal
    Creates two new parameters tokens
    ? For single argument
    . . . for multiple parameters
    

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55. @wmsbill
    Partial application syntax
    

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56. @wmsbill
    With arbitrary parameter
    

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58. @wmsbill
    The . . . token
    Spread the unbound parameters
    Useful when you want to bound first
    or last parameter
    

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59. @wmsbill
    The . . . token
    

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60. @wmsbill
    The . . . token
    

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62. @wmsbill
    Partial application + pipeline
    

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63. @wmsbill
    Partial application + pipeline
    

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64. @wmsbill
    Should I use all of it in production?
    These proposal are in very early
    stage
    The adoption of one, may change
    the syntax/semantics of other
    Not production ready (yet)
    

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65. https://medium.com/@wmsbill
    https://twitter.com/wmsbill
    wmsbill@gmail.com
    

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66. Dankeshön!
    

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