Papers we love: Elixir edition

Transcript

1. PAPERS WE LOVE
   ELIXIR EDITION
   PAPERS WE LOVE
   ELIXIR EDITION
   

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2. @whatyouhide
   

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8. “You know Yelp?
   Yeah, but for weed”– me
   

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11. “You know Uber Eats?”– me
    

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13. weedmaps.com/careers
    

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14. ELIXIR
    functional
    concurrent
    fault tolerant
    

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15. The Elixir core team
    

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16. we existing research
    

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17. Formatting code
    Diffing data structures
    Property-based testing ⚙
    

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18. FORMATTING CODE
    

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19. Code formatter
    welcoming to newcomers
    consistency across teams/orgs/community
    no style discussions
    

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20. print code with line length limit
    

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21. %{foo: [1, 2, 3], bar: "baz"}
    

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22. %{foo: [1, 2, 3], bar: "baz"}
    30
    

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23. %{foo: [1, 2, 3], bar: "baz"}
    25
    

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24. %{
    foo: [1, 2, 3],
    bar: "baz"
    }
    25
    

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25. %{
    foo: [1, 2, 3],
    bar: "baz"
    }
    13
    

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26. %{
    foo: [
    1,
    2,
    3
    ],
    bar: "baz"
    }
    13
    

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27. The Design of a Pretty-printing Library
    John Hughes
    

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28. Documents
    "text"
    concat(document1, document2)
    nest(document, columns)
    

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29. "["
    |> concat("1,")
    |> concat("2,")
    |> concat("3")
    |> concat("]")
    [1, 2, 3]
    

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30. "["
    |> line("1,")
    |> line("2,")
    |> line("3")
    |> nest(2)
    |> line("]")
    [
    1,
    2,
    3
    ]
    

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31. A Prettier Printer
    Philip Wadler
    

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32. group(
    "["
    |> concat("1,")
    |> concat("2,")
    |> concat("3")
    |> nest(2)
    |> concat("]")
    )
    [
    1,
    2,
    3
    ]
    

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33. choose(
    doc,
    replace_concat_with_line_break(doc)
    ) DANGER:
    STRICT LANGUAGE AHEAD
    

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34. Strictly Pretty
    Christian Lindig
    

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35. Our documents
    color(doc, :blue)
    nest(doc, :cursor)
    ...
    

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36. DIFFING
    DATA STRUCTURES
    

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37. 1) test two strings are different (Test)
    test.ex:6
    Assertion with == failed
    code: assert "hello world!" == "Hello, my world"
    left: "hello world!"
    right: "Hello, my world"
    stacktrace:
    test.ex:7: (test)
    

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39. An O(ND) Difference Algorithm
    and Its Variations
    Eugene W. Myers
    

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40. “Find the shortest edit script to turn
    a sequence A into a sequence B.”
    = Find shortest path
    in a graph
    

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41. O(ND)
    D is related to how
    "similar" the two
    sequences are
    DNA strand mutation
    source code changes
    

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42. iex> List.myers_difference([1, 4, 2, 3], [1, 2, 3, 4])
    [eq: [1], del: [4], eq: [2, 3], ins: [4]]
    

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43. Now colorize
    

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44. No modifications to
    the paper this time
    

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45. String Matching with Metric Trees
    Using an Approximate Distance
    Ilaria Bartolini, Paolo Ciaccia, Marco Patella
    

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46. PROPERTY-BASED
    TESTING
    

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47. Shape of input
    Properties of output
    +
    +
    Randomness
    =
    Property-based testing
    

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48. check all list <- list_of(term()) do
    sorted = sort(list)
    assert is_list(sorted)
    assert length(list) == length(sorted)
    end
    

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49. String.starts_with?(s1 <> s2, s1)
    String.ends_with?(s1 <> s2, s2)
    For any strings s1 and s2:
    

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50. Only Erlang tools
    (with different license)
    

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51. QuickCheck: A Lightweight Tool for
    Random Testing of Haskell Programs
    Koen Classen John Hughes
    

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52. all the base ideas are there
    but it relies too
    heavily on types
    

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53. data Colour = Red | Blue | Green
    instance Arbitrary Colour where
    arbitrary = oneof
    [return Red, return Blue, return Green]
    

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54. (prop/for-all [v (gen/vector gen/int)]
    (= (sort v) (sort (sort v))))
    Clojure's test.check
    

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55. StreamData
    check all s1 <- string(),
    s2 <- string() do
    assert String.starts_with?(s1 <> s2, s1)
    assert String.ends_with?(s1 <> s2, s2)
    end
    

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56. Generators
    functions that take
    some random state
    and return a lazy tree
    

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57. Lazy tree
    a value plus a "recipe"
    for shrinking it
    

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58. StreamData.integer()
    3
    0
    2
    0
    1
    0
    

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59. StreamData.integer()
    3
    0
    2
    0
    1
    0
    

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60. map(StreamData.integer(), fn x -> x * 2 end)
    3 * 2
    0 * 2
    2 * 2
    0 * 2
    1 * 2
    0 * 2
    

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61. map(StreamData.integer(), fn x -> x * 2 end)
    6
    0
    4
    0
    2
    0
    

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62. HONORABLE
    MENTIONS
    

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63. How to make ad-hoc
    polymorphism less ad hoc
    Philip Wadler
    Stephen Blott
    

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64. Recursive functions of
    symbolic expressions and their
    computation by machine
    John McCarthy
    

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65. Advances in record
    linkage methodology as
    applied to the 1985
    census of Tampa Florida
    Matthew A. Jaro
    

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66. Iteratee: Teaching an Old
    Fold New Tricks
    John W. Lato
    

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67. CONCLUSIONS
    

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68. Existing research
    is AWESOME
    

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69. Research tends to solve problems in a
    general/simple/flexible/elegant way
    

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70. HDD
    Hughes-driven development
    

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71. @whatyouhide
    

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