Ruby Pattern Matching

Pattern matching is a great way to build Command Line Interfaces (CLIs), deal with third-party Application Programming Interfaces (APIs), and much more. In this presentation you'll learn what pattern matching is and how to leverage the power of pattern matching within your own Ruby applications!

Transcript

1. Ruby Pattern Matching Brooke Kuhlmann alchemists.io
2. en.wikipedia.org/wiki/Pattern_matching What alchemists.io
3. en.wikipedia.org/wiki/Pattern_matching What Pattern matching is the act of checking a given sequence of tokens for the presence of the constituents of some pattern. alchemists.io
4. What alchemists.io
5. What { ship: "Serenity", crew: [ { name: "Malcolm Reynolds", title: "Captain" }, { name: "Zoe Alleyne Washburne", title: "Fighter" }, { name: "Kaywinnet Lee Frye" title: "Engineer" } ] } alchemists.io
6. What { ship: "Serenity", crew: [ { name: "Malcolm Reynolds", title: "Captain" }, { name: "Zoe Alleyne Washburne", title: "Fighter" }, { name: "Kaywinnet Lee Frye" title: "Engineer" } ] } alchemists.io
7. What { ship: "Serenity", crew: [ { name: "Malcolm Reynolds", title: "Captain" }, { name: "Zoe Alleyne Washburne", title: "Fighter" }, { name: "Kaywinnet Lee Frye" title: "Engineer" } ] } alchemists.io
8. What { ship: "Serenity", crew: [ { name: "Malcolm Reynolds", title: "Captain" }, { name: "Zoe Alleyne Washburne", title: "Fighter" }, { name: "Kaywinnet Lee Frye" title: "Engineer" } ] } alchemists.io
9. What { ship: "Serenity", crew: [ { name: "Malcolm Reynolds", title: "Captain" }, { name: "Zoe Alleyne Washburne", title: "Fighter" }, { name: "Kaywinnet Lee Frye" title: "Engineer" } ] } alchemists.io
10. alchemists.io/articles/ruby_pattern_matching Overview alchemists.io
11. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes The Joy of Pattern Matching! alchemists.io
12. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => The Joy of Pattern Matching! alchemists.io
13. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] The Joy of Pattern Matching! alchemists.io
14. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} The Joy of Pattern Matching! alchemists.io
15. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder The Joy of Pattern Matching! alchemists.io
16. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] The Joy of Pattern Matching! alchemists.io
17. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] The Joy of Pattern Matching! _ alchemists.io
18. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] **nil The Joy of Pattern Matching! _ alchemists.io
19. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] **nil ^variable The Joy of Pattern Matching! _ alchemists.io
20. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] **nil ^variable | The Joy of Pattern Matching! _ alchemists.io
21. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] **nil ^variable | if, unless The Joy of Pattern Matching! _ alchemists.io
22. alchemists.io/articles/ruby_pattern_matching Overview • Standalone • Arrays • Hashes • Remainders • Finds • Excludes • Voids • Variable Binding • Combinations • Guards • Classes in, => [<pattern>, <pattern>] {key: <pattern>, key: <pattern>} *, **, *remainder, **remainder [*, <pattern>, *] **nil ^variable | if, unless desconstruct, desconstruct_keys The Joy of Pattern Matching! _ alchemists.io
23. History alchemists.io alchemists.io/articles/ruby_pattern_matching
24. History • Ruby 2.7.0: Introduced alchemists.io alchemists.io/articles/ruby_pattern_matching
25. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: alchemists.io alchemists.io/articles/ruby_pattern_matching
26. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: • Standalone rightward assignment (i.e. =>). alchemists.io alchemists.io/articles/ruby_pattern_matching
27. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: • Standalone rightward assignment (i.e. =>). • Standalone boolean checks (i.e. in). alchemists.io alchemists.io/articles/ruby_pattern_matching
28. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: • Standalone rightward assignment (i.e. =>). • Standalone boolean checks (i.e. in). • Find patterns (i.e. <object> in [*, query, \*]). alchemists.io alchemists.io/articles/ruby_pattern_matching
29. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: • Standalone rightward assignment (i.e. =>). • Standalone boolean checks (i.e. in). • Find patterns (i.e. <object> in [*, query, \*]). • Ruby 3.1.0: Rightward assignment and boolean checks became of fi cially supported. alchemists.io alchemists.io/articles/ruby_pattern_matching
30. History • Ruby 2.7.0: Introduced • Ruby 3.0.0: Of fi cially supported with new experimental features: • Standalone rightward assignment (i.e. =>). • Standalone boolean checks (i.e. in). • Find patterns (i.e. <object> in [*, query, \*]). • Ruby 3.1.0: Rightward assignment and boolean checks became of fi cially supported. • Pin operator (i.e. ^) gained the ability to use statements and/or more complex expressions instead of only constants, literals, and local variables. alchemists.io alchemists.io/articles/ruby_pattern_matching
31. Syntax: Standalone alchemists.io
32. Syntax: Standalone <expression> in <pattern> <expression> => <pattern> alchemists.io alchemists.io/articles/ruby_pattern_matching
33. Syntax: Standalone <expression> in <pattern> <expression> => <pattern> 💡 True || False alchemists.io alchemists.io/articles/ruby_pattern_matching
34. Syntax: Standalone <expression> in <pattern> <expression> => <pattern> 💡 True || False 💡 Assignment alchemists.io alchemists.io/articles/ruby_pattern_matching
35. Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
36. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
37. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
38. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
39. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
40. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
41. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
42. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } true Syntax: Standalone (in) alchemists.io alchemists.io/articles/ruby_pattern_matching
43. basket = [{kind: "apple", quantity: 1}, {kind: "peach", quantity: 5}] basket.any? { |fruit| fruit in {kind: /app/} } true Syntax: Standalone (in) 🚫 ✅ alchemists.io alchemists.io/articles/ruby_pattern_matching
44. Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
45. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
46. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
47. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) Pattern alchemists.io alchemists.io/articles/ruby_pattern_matching
48. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
49. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
50. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
51. {character: {first_name: "Malcolm", last_name: "Reynolds"}} => {character: {last_name:}} puts "Last Name: #{last_name}" Last Name: Reynolds Syntax: Standalone (=>) alchemists.io alchemists.io/articles/ruby_pattern_matching
52. Syntax: Case alchemists.io
53. Syntax: Case case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... else ... end alchemists.io alchemists.io/articles/ruby_pattern_matching
54. Syntax: Case case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... else ... end alchemists.io alchemists.io/articles/ruby_pattern_matching
55. case <expression> in <pattern> then ... when <pattern> then ... else ... end Syntax: Case alchemists.io alchemists.io/articles/ruby_pattern_matching
56. case <expression> in <pattern> then ... when <pattern> then ... else ... end Syntax: Case alchemists.io alchemists.io/articles/ruby_pattern_matching
57. Syntax: Case alchemists.io alchemists.io/articles/ruby_pattern_matching
58. c ccc c cc c c c c ccccc e ee Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
59. NoMatchingPatternError Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
60. NoMatchingPatternError ♥ Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
61. NoMatchingPatternError ♥ Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
62. Control Flow Pattern Matching Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
63. case <expression> when <pattern> then ... when <pattern> then ... when <pattern> then ... end case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... end Control Flow Pattern Matching Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
64. case <expression> when <pattern> then ... when <pattern> then ... when <pattern> then ... end case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... end Control Flow Pattern Matching Nothing Happens 😢 Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
65. case <expression> when <pattern> then ... when <pattern> then ... when <pattern> then ... end case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... end Control Flow Pattern Matching Nothing Happens 😢 NoMatchingPatternError 🎉 Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
66. case <expression> when <pattern> then ... when <pattern> then ... when <pattern> then ... end case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... end Control Flow Pattern Matching Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
67. case <expression> when <pattern> then ... when <pattern> then ... when <pattern> then ... end case <expression> in <pattern> then ... in <pattern> then ... in <pattern> then ... end Control Flow Pattern Matching Style/MissingElse: Enabled: true Syntax: Case (Exhaustive Matching) alchemists.io alchemists.io/articles/ruby_pattern_matching
68. Syntax: Optional alchemists.io alchemists.io/articles/ruby_pattern_matching
69. case [1, 2, 3] in [Integer, Integer] then "match" else "unmatched" end case {a: 1, b: 2, c: 3} in {a: Integer} then "matched" else "unmatched" end Syntax: Optional alchemists.io alchemists.io/articles/ruby_pattern_matching
70. case [1, 2, 3] in Integer, Integer then "match" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end Syntax: Optional alchemists.io alchemists.io/articles/ruby_pattern_matching
71. case [1, 2, 3] in Integer, Integer then "match" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end Syntax: Optional alchemists.io alchemists.io/articles/ruby_pattern_matching
72. case [1, 2, 3] in Integer, Integer then "match" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end Syntax: Optional ⚠ Required for standalone syntax alchemists.io alchemists.io/articles/ruby_pattern_matching
73. Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
74. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end Array Hash Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
75. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end "unmatched" Array Hash Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
76. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end "unmatched" Array Hash Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
77. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end "unmatched" Array Hash Whole Versus Partial 💡 Order Matters alchemists.io alchemists.io/articles/ruby_pattern_matching
78. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end "unmatched" "matched" Array Hash Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
79. case [1, 2, 3] in Integer, Integer then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer then "matched" else "unmatched" end "unmatched" "matched" Array Hash Whole Versus Partial alchemists.io alchemists.io/articles/ruby_pattern_matching
80. Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
81. case {a: 1, b: 2, c: 3} in {} then "matched" else "unmatched" end case {} in {} then "matched" else "unmatched" end With Content Without Content Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
82. case {a: 1, b: 2, c: 3} in {} then "matched" else "unmatched" end case {} in {} then "matched" else "unmatched" end With Content Without Content Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
83. case {a: 1, b: 2, c: 3} in {} then "matched" else "unmatched" end case {} in {} then "matched" else "unmatched" end "unmatched" With Content Without Content Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
84. case {a: 1, b: 2, c: 3} in {} then "matched" else "unmatched" end case {} in {} then "matched" else "unmatched" end "unmatched" With Content Without Content Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
85. case {a: 1, b: 2, c: 3} in {} then "matched" else "unmatched" end case {} in {} then "matched" else "unmatched" end "unmatched" "matched" With Content Without Content Caveat: Empty Hashes alchemists.io alchemists.io/articles/ruby_pattern_matching
86. Finds alchemists.io alchemists.io/articles/ruby_pattern_matching
87. case [:a, 1, :b, :c, 2] in *, Symbol, Symbol, * then "matched" else "unmatched" end Arrays Only Finds alchemists.io alchemists.io/articles/ruby_pattern_matching
88. case [:a, 1, :b, :c, 2] in *, Symbol, Symbol, * then "matched" else "unmatched" end Arrays Only Finds alchemists.io alchemists.io/articles/ruby_pattern_matching
89. case [:a, 1, :b, :c, 2] in *, Symbol, Symbol, * then "matched" else "unmatched" end Arrays Only Finds alchemists.io alchemists.io/articles/ruby_pattern_matching
90. case [:a, 1, :b, :c, 2] in *, Symbol, Symbol, * then "matched" else "unmatched" end "matched" Arrays Only Finds alchemists.io alchemists.io/articles/ruby_pattern_matching
91. case [:a, 1, :b, :c, 2] in *, Symbol, Symbol, * then "matched" else "unmatched" end "matched" Arrays Only Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
92. Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
93. case [:a, 1, :b, :c, 2] in *first, Symbol, Symbol, *last then {first: first, last: last} else "unmatched" end Arrays Only Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
94. case [:a, 1, :b, :c, 2] in *first, Symbol, Symbol, *last then {first: first, last: last} else "unmatched" end Arrays Only Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
95. case [:a, 1, :b, :c, 2] in *first, Symbol, Symbol, *last then {first: first, last: last} else "unmatched" end { fi rst: [:a, 1], last: [2]} Arrays Only Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
96. case [:a, 1, :b, :c, 2] in *first, Symbol, Symbol, *last then {first: first, last: last} else "unmatched" end { fi rst: [:a, 1], last: [2]} Arrays Only Finds ⚠ Expensive alchemists.io alchemists.io/articles/ruby_pattern_matching
97. Voids alchemists.io alchemists.io/articles/ruby_pattern_matching
98. case {a: 1, b: 2} in {a: Integer, **nil} then %(matched "a" part) in {a: Integer, b: Integer, **nil} then "matched whole hash" else "unmatched" end Hashes Only Voids alchemists.io alchemists.io/articles/ruby_pattern_matching
99. case {a: 1, b: 2} in {a: Integer, **nil} then %(matched "a" part) in {a: Integer, b: Integer, **nil} then "matched whole hash" else "unmatched" end "matched whole hash" Hashes Only Voids alchemists.io alchemists.io/articles/ruby_pattern_matching
100. case {a: 1, b: 2} in {a: Integer, **nil} then %(matched "a" part) in {a: Integer, b: Integer, **nil} then "matched whole hash" else "unmatched" end "matched whole hash" Hashes Only Voids alchemists.io alchemists.io/articles/ruby_pattern_matching
101. case {a: 1, b: 2} in {a: Integer, **nil} then %(matched "a" part) in {a: Integer, b: Integer, **nil} then "matched whole hash" else "unmatched" end "matched whole hash" Hashes Only ⚠ Pattern end only Voids alchemists.io alchemists.io/articles/ruby_pattern_matching
102. case {a: 1, b: 2} in {a: Integer, **nil} then %(matched "a" part) in {a: Integer, b: Integer, **nil} then "matched whole hash" else "unmatched" end "matched whole hash" Hashes Only Voids ✅ alchemists.io alchemists.io/articles/ruby_pattern_matching
103. Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
104. case [1, 2, 3] in Integer, * then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer, ** then "matched" else "unmatched" end Array Hash Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
105. case [1, 2, 3] in Integer, * then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer, ** then "matched" else "unmatched" end Array Hash Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
106. case [1, 2, 3] in Integer, * then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer, ** then "matched" else "unmatched" end "matched" Array Hash Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
107. case [1, 2, 3] in Integer, * then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer, ** then "matched" else "unmatched" end "matched" Array Hash Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
108. case [1, 2, 3] in Integer, * then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in a: Integer, ** then "matched" else "unmatched" end "matched" "matched" Array Hash Remainders alchemists.io alchemists.io/articles/ruby_pattern_matching
109. Variable Binding alchemists.io alchemists.io/articles/ruby_pattern_matching
110. case [1, 2] in Integer => first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: Integer => first then "matched: #{first}" else "unmatched" end Array Variable Binding Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
111. case [1, 2] in Integer => first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: Integer => first then "matched: #{first}" else "unmatched" end Array Variable Binding Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
112. case [1, 2] in Integer => first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: Integer => first then "matched: #{first}" else "unmatched" end "matched: 1" Array Variable Binding Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
113. case [1, 2] in Integer => first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: Integer => first then "matched: #{first}" else "unmatched" end "matched: 1" Array Variable Binding Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
114. case [1, 2] in Integer => first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: Integer => first then "matched: #{first}" else "unmatched" end "matched: 1" "matched: 1" Array Variable Binding Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
115. Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
116. case [1, 2] in first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: first then "matched: #{first}" else "unmatched" end Array Hash Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
117. case [1, 2] in first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: first then "matched: #{first}" else "unmatched" end Array Hash Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
118. case [1, 2] in first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: first then "matched: #{first}" else "unmatched" end "matched: 1" Array Hash Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
119. case [1, 2] in first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: first then "matched: #{first}" else "unmatched" end "matched: 1" Array Hash Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
120. case [1, 2] in first, Integer then "matched: #{first}" else "unmatched" end case {a: 1, b: 2} in a: first then "matched: #{first}" else "unmatched" end "matched: 1" "matched: 1" Array Hash Variable Binding: Simpli fi ed alchemists.io alchemists.io/articles/ruby_pattern_matching
121. Variable Binding: Hash Only alchemists.io alchemists.io/articles/ruby_pattern_matching
122. case {a: 1, b: 2} in a: then "matched: #{a}" else "unmatched" end Variable Binding: Hash Only alchemists.io alchemists.io/articles/ruby_pattern_matching
123. case {a: 1, b: 2} in a: then "matched: #{a}" else "unmatched" end Variable Binding: Hash Only alchemists.io alchemists.io/articles/ruby_pattern_matching
124. case {a: 1, b: 2} in a: then "matched: #{a}" else "unmatched" end "matched: 1" Variable Binding: Hash Only alchemists.io alchemists.io/articles/ruby_pattern_matching
125. Explicit Brackets Variable Binding: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
126. case [%w[Apple Apricot], %w[Blueberry Blackberry]] in [[first, String], *] then "matched: #{first}" else "unmatched" end case {label: "Basket", fruits: [{label: "Apple"}, {label: "Peach"}]} in label:, fruits: [{label: first}, *] then "matched: #{first}" else "unmatched" end Array Hash Explicit Brackets Variable Binding: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
127. case [%w[Apple Apricot], %w[Blueberry Blackberry]] in [[first, String], *] then "matched: #{first}" else "unmatched" end case {label: "Basket", fruits: [{label: "Apple"}, {label: "Peach"}]} in label:, fruits: [{label: first}, *] then "matched: #{first}" else "unmatched" end Array Hash Explicit Brackets Variable Binding: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
128. case [%w[Apple Apricot], %w[Blueberry Blackberry]] in [[first, String], *] then "matched: #{first}" else "unmatched" end case {label: "Basket", fruits: [{label: "Apple"}, {label: "Peach"}]} in label:, fruits: [{label: first}, *] then "matched: #{first}" else "unmatched" end "matched: Apple" "matched: Apple" Array Hash Explicit Brackets Variable Binding: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
129. Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
130. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
131. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
132. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
133. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end "matched: 1, [2, 3]" Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
134. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end "matched: 1, [2, 3]" Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
135. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end "matched: 1, [2, 3]" Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
136. case [1, 2, 3] in first, *remainder then "matched: #{first}, #{remainder}" else "unmatched" end case {a: 1, b: 2, c: 3} in a:, **remainder then "matched: #{a}, #{remainder}" else "unmatched" end "matched: 1, {:b=>2, :c=>3}" "matched: 1, [2, 3]" Array Hash Variable Binding: Remainder alchemists.io alchemists.io/articles/ruby_pattern_matching
137. Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
138. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
139. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
140. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
141. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
142. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end "matched: 1" Variable Pinning alchemists.io alchemists.io/articles/ruby_pattern_matching
143. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end "matched: 1" Variable Pinning `expectation` is pinned to `1` alchemists.io alchemists.io/articles/ruby_pattern_matching
144. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end "matched: 1" "unmatched: 5" Variable Pinning `expectation` is pinned to `1` alchemists.io alchemists.io/articles/ruby_pattern_matching
145. expectation = 5 case [1, 2] in expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end expectation = 5 case [1, 2] in ^expectation, * then "matched: #{expectation}" else "unmatched: #{expectation}" end "matched: 1" "unmatched: 5" Variable Pinning `expectation` is pinned to `1` `expectation` is pinned to `5` alchemists.io alchemists.io/articles/ruby_pattern_matching
146. Variable Pinning: Comparison alchemists.io alchemists.io/articles/ruby_pattern_matching
147. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end Variable Pinning: Comparison alchemists.io alchemists.io/articles/ruby_pattern_matching
148. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" Variable Pinning: Comparison alchemists.io alchemists.io/articles/ruby_pattern_matching
149. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" "values are different" Variable Pinning: Comparison alchemists.io alchemists.io/articles/ruby_pattern_matching
150. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" "values are different" Variable Pinning: Comparison 1 alchemists.io alchemists.io/articles/ruby_pattern_matching
151. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" "values are different" Variable Pinning: Comparison 1 1 alchemists.io alchemists.io/articles/ruby_pattern_matching
152. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" "values are different" Variable Pinning: Comparison 1 1 alchemists.io alchemists.io/articles/ruby_pattern_matching
153. case [1, 1] in value, ^value then "values are identical" else "values are different" end case [1, 2] in value, ^value then "values are identical" else "values are different" end "values are identical" "values are different" Variable Pinning: Comparison 1 1 1 1 alchemists.io alchemists.io/articles/ruby_pattern_matching
154. Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
155. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
156. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
157. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" Key Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
158. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" Pin Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
159. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" Value Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
160. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" Value Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
161. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" ✅ Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
162. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" "unmatched" Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
163. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" "unmatched" Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
164. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" "unmatched" Pin ("high") Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
165. case {school: "high", schools: [{id: 1, level: "middle"}, {id: 2, level: "high"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end case {school: "high", schools: [{id: 1, level: "middle"}]} in school:, schools: [*, {id:, level: ^school}] then "matched: #{id}" else "unmatched" end "matched: 2" "unmatched" Pin ("high") "middle" != "high" Variable Pinning: Nested alchemists.io alchemists.io/articles/ruby_pattern_matching
166. Variable Pinning: Expression alchemists.io alchemists.io/articles/ruby_pattern_matching
167. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end Variable Pinning: Expression alchemists.io alchemists.io/articles/ruby_pattern_matching
168. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end Variable Pinning: Expression alchemists.io alchemists.io/articles/ruby_pattern_matching
169. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end Variable Pinning: Expression alchemists.io alchemists.io/articles/ruby_pattern_matching
170. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end "matched" Variable Pinning: Expression alchemists.io alchemists.io/articles/ruby_pattern_matching
171. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end "matched" Variable Pinning: Expression multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) => expectation then "matched: #{expectation}" else "unmatched: #{expectation}" end alchemists.io alchemists.io/articles/ruby_pattern_matching
172. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end "matched" Variable Pinning: Expression multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) => expectation then "matched: #{expectation}" else "unmatched: #{expectation}" end alchemists.io alchemists.io/articles/ruby_pattern_matching
173. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end "matched" Variable Pinning: Expression multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) => expectation then "matched: #{expectation}" else "unmatched: #{expectation}" end alchemists.io alchemists.io/articles/ruby_pattern_matching
174. multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) then "matched" else "unmatched" end "matched" Variable Pinning: Expression multiplier = 2 case [2, 4] in Integer, ^(2 * multiplier) => expectation then "matched: #{expectation}" else "unmatched: #{expectation}" end "matched: 4" alchemists.io alchemists.io/articles/ruby_pattern_matching
175. Combinations alchemists.io alchemists.io/articles/ruby_pattern_matching
176. Combinations case [:a, 1, 2.0] in String | Symbol, Integer, Float then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in Array | {a: Integer} then "matched" else "unmatched" end Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
177. Combinations case [:a, 1, 2.0] in String | Symbol, Integer, Float then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in Array | {a: Integer} then "matched" else "unmatched" end Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
178. Combinations case [:a, 1, 2.0] in String | Symbol, Integer, Float then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in Array | {a: Integer} then "matched" else "unmatched" end "matched" Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
179. Combinations case [:a, 1, 2.0] in String | Symbol, Integer, Float then "matched" else "unmatched" end case {a: 1, b: 2, c: 3} in Array | {a: Integer} then "matched" else "unmatched" end "matched" "matched" Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
180. Combinations alchemists.io alchemists.io/articles/ruby_pattern_matching
181. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end alchemists.io alchemists.io/articles/ruby_pattern_matching
182. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end illegal variable in alternative pattern (a) (SyntaxError) Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end 🚫 alchemists.io alchemists.io/articles/ruby_pattern_matching
183. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end illegal variable in alternative pattern (a) (SyntaxError) Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end 🚫 alchemists.io alchemists.io/articles/ruby_pattern_matching
184. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end illegal variable in alternative pattern (a) (SyntaxError) Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end matched 🚫 🚫 alchemists.io alchemists.io/articles/ruby_pattern_matching
185. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end illegal variable in alternative pattern (a) (SyntaxError) Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end matched 🚫 🚫 alchemists.io alchemists.io/articles/ruby_pattern_matching
186. Combinations case {a: 1, b: 2, c: 3} in {a:} | Array then "matched" else "unmatched" end illegal variable in alternative pattern (a) (SyntaxError) Hash Only case {a: 1, b: 2, c: 3} in {a: _} | Array then "matched" else "unmatched" end matched 🚫 🚫 Meant to signify discarded values only! alchemists.io alchemists.io/articles/ruby_pattern_matching
187. Guards alchemists.io alchemists.io/articles/ruby_pattern_matching
188. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
189. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end "matched" "matched" Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
190. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end "matched" "matched" Array Hash alchemists.io alchemists.io/articles/ruby_pattern_matching
191. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end "matched" "matched" Array Hash 💡`unless` works too! alchemists.io alchemists.io/articles/ruby_pattern_matching
192. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end "matched" "matched" Array Hash 💡`unless` works too! alchemists.io alchemists.io/articles/ruby_pattern_matching
193. Guards case %w[apple peach blueberry] in String, middle, String if middle == "peach" then "matched" else "unmatched" end case {animal: "bat", vehicle: "tumbler", color: "black"} in {color: String} if color == "black" then "matched" else "unmatched" end "matched" "matched" Array Hash 💡`unless` works too! alchemists.io alchemists.io/articles/ruby_pattern_matching
194. Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
195. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
196. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end Array Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
197. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end Array Hash Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
198. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end Array Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
199. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end # => "matched: 1" Array Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
200. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end # => "matched: 1" Array Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
201. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end # => "matched: 1" case Point.new 1, -2 in x: 0.. then "matched: #{x}" else "unmatched" end Array Pattern Hash Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
202. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end # => "matched: 1" case Point.new 1, -2 in x: 0.. then "matched: #{x}" else "unmatched" end # => "matched: 1" Array Pattern Hash Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
203. class Point attr_reader :x, :y def initialize x, y @x = x @y = y end def deconstruct = [x, y] def deconstruct_keys(keys) = {x: x, y: y} end case Point.new 1, -2 in x, Integer then "matched: #{x}" else "unmatched" end # => "matched: 1" case Point.new 1, -2 in x: 0.. then "matched: #{x}" else "unmatched" end # => "matched: 1" Array Pattern Hash Pattern Classes alchemists.io alchemists.io/articles/ruby_pattern_matching
204. Structs alchemists.io alchemists.io/articles/ruby_pattern_matching
205. Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
206. case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
207. case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
208. case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y Same Type alchemists.io alchemists.io/articles/ruby_pattern_matching
209. case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y Point[..5, ..5] alchemists.io alchemists.io/articles/ruby_pattern_matching
210. case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y Point[..5, ..5] Type[pattern] alchemists.io alchemists.io/articles/ruby_pattern_matching
211. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
212. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y "matched" alchemists.io alchemists.io/articles/ruby_pattern_matching
213. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y "matched" Same Type alchemists.io alchemists.io/articles/ruby_pattern_matching
214. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case [1, 2] in Point[..5, ..5] then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y "matched" alchemists.io alchemists.io/articles/ruby_pattern_matching
215. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case [1, 2] in Point[..5, ..5] then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y "matched" "unmatched" alchemists.io alchemists.io/articles/ruby_pattern_matching
216. case Point[1, 2] in ..5, ..5 then "matched" else "unmatched" end case [1, 2] in Point[..5, ..5] then "matched" else "unmatched" end case Point[1, 2] in Point[..5, ..5] then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y Wrong Type "matched" "unmatched" alchemists.io alchemists.io/articles/ruby_pattern_matching
217. Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
218. case Point[1, 2] in Point(x:, y:) then "matched" else "unmatched" end Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
219. case Point[1, 2] in Point(x:, y:) then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
220. case Point[1, 2] in Point(x:, y:) then "matched" else "unmatched" end "matched" Structs Point = Struct.new :x, :y alchemists.io alchemists.io/articles/ruby_pattern_matching
221. alchemists.io/projects alchemists.io
222. Examples alchemists.io/projects alchemists.io
223. alchemists.io/projects/rubysmith alchemists.io
224. Rubysmith alchemists.io/projects/rubysmith alchemists.io
225. alchemists.io/projects/rubysmith Rubysmith alchemists.io
226. alchemists.io/projects/rubysmith Rubysmith alchemists.io
227. Rubysmith alchemists.io alchemists.io/projects/rubysmith
228. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
229. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
230. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
231. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
232. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
233. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
234. module Rubysmith module CLI # The main Command Line Interface (CLI) object. class Shell # Truncated. def call arguments = [] case parse arguments in action_config: Symbol => action then config.call action in action_build: true then build.call in action_version: true then logger.info { configuration.version } else logger.any { parser.to_s } end end end end end Rubysmith alchemists.io alchemists.io/projects/rubysmith
235. alchemists.io/talks/janus alchemists.io
236. Janus alchemists.io/talks/janus alchemists.io
237. Janus 🎉 Open Sourced (future) alchemists.io/talks/janus alchemists.io
238. Janus alchemists.io alchemists.io/talks/janus
239. Janus alchemists.io alchemists.io/talks/janus
240. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
241. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
242. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
243. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
244. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
245. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
246. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
247. module Janus module Actions class Processor # Trunctated. def call request # Trunctated. text = request.text case text.split in ["help"] then help in "status" => status, String => name then status.call name in "version", String => name, String => version then version.call name, version in "deploy", String => name, String => version then deploy.call name, version else unknown.call text end end end end end Janus alchemists.io alchemists.io/talks/janus
248. alchemists.io
249. Guidelines 💡 alchemists.io
250. Guidelines alchemists.io/articles/ruby_pattern_matching alchemists.io
251. Guidelines • Use sorted arrays. alchemists.io/articles/ruby_pattern_matching alchemists.io
252. Guidelines • Use sorted arrays. • Use limited fi nds: [*, <pattern>, *]. alchemists.io/articles/ruby_pattern_matching alchemists.io
253. Guidelines • Use sorted arrays. • Use limited fi nds: [*, <pattern>, *]. • Avoid unnecessary deconstruction. alchemists.io/articles/ruby_pattern_matching alchemists.io
254. Guidelines • Use sorted arrays. • Use limited fi nds: [*, <pattern>, *]. • Avoid unnecessary deconstruction. • Avoid shadow variables. alchemists.io/articles/ruby_pattern_matching alchemists.io
255. Guidelines • Use sorted arrays. • Use limited fi nds: [*, <pattern>, *]. • Avoid unnecessary deconstruction. • Avoid shadow variables. • Avoid complicated nested patterns. alchemists.io/articles/ruby_pattern_matching alchemists.io
256. Thanks alchemists.io
257. 🙇 Thanks alchemists.io
258. Let's Connect! alchemists.io @bkuhlmann@mastodon.social