関数潮流(Function Tendency)
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The document shows examples of using lambda functions and functional programming techniques in various languages like JavaScript, Python, C#, and Java. It demonstrates how to define anonymous functions, map, filter and reduce collections, use closures, and more. Key examples include summing a list of integers with reduce, filtering even numbers from a list, mapping string transformations, and converting a list of strings to uppercase.
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関数潮流(Function Tendency)
- 76. js> function add2(x) { return x + 2; } js> add2(5); 7 js> var f = function(x) { return x + 2; } js> f(8); 10 js> (function(x) { return x + 2; })(9) 11
- 77. js> function add2(x) { return x + 2; } js> add2(5); 7 js> var f = function(x) { return x + 2; } js> f(8); 10 js> (function(x) { return x + 2; })(9) 11
- 78. js> function add2(x) { return x + 2; } js> add2(5); 7 js> var f = function(x) { return x + 2; } js> f(8); 10 js> (function(x) { return x + 2; })(9) 11
- 79. js> function add2(x) { return x + 2; } js> add2(5); 7 js> var f = function(x) { return x + 2; } js> f(8); 10 js> (function(x) { return x + 2; })(9) 11
- 80. js> function add2(x) { return x + 2; } js> add2(5); 7 js> var f = function(x) { return x + 2; } js> f(8); 10 js> (function(x) { return x + 2; })(9) 11
- 81. Func<int, int> f = (x) => x + 2; var f = function(x) { return x + 2; } f = lambda x: x + 2; f = x -> x + 2 (fset 'f (lambda (x) (+ x 2)))
- 87. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 88. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 89. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 90. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 91. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 92. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 93. Func<string, string> foo(Func<DateTime, string> f) { return x => x.ToUpper() + " " + f(DateTime.Today); } Func<DateTime, string> d = x => x.Year + "/" + x.Month; Func<string, string> c = foo(d); string result = c("oblove"); “OBLOVE 2011/7”
- 104. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 105. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 106. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 107. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 108. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 109. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 110. int sum(int acc, IEnumerable<int> list) { if (!list.Any()) { return acc; } int head = list.First(); return sum(acc + head, list.Skip(1)); } List<int> ls = new List<int> { 3, 5, 8 }; int result = sum(0, ls);
- 117. >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), s) ['C#', 'JAVA', 'PYTHON'] >>> map(lambda x: len(x), s) [2, 4, 6]
- 118. >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), s) ['C#', 'JAVA', 'PYTHON'] >>> map(lambda x: len(x), s) [2, 4, 6]
- 119. >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), s) ['C#', 'JAVA', 'PYTHON'] >>> map(lambda x: len(x), s) [2, 4, 6]
- 120. >>> s = [1, 2, 3, 4, 5, 6] >>> filter(lambda x: x % 2 == 0, s) [2, 4, 6] >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), filter(lambda x: len(x) > 3, s)) ['JAVA', 'PYTHON']
- 121. >>> s = [1, 2, 3, 4, 5, 6] >>> filter(lambda x: x % 2 == 0, s) [2, 4, 6] >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), filter(lambda x: len(x) > 3, s)) ['JAVA', 'PYTHON']
- 122. >>> s = [1, 2, 3, 4, 5, 6] >>> filter(lambda x: x % 2 == 0, s) [2, 4, 6] >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), filter(lambda x: len(x) > 3, s)) ['JAVA', 'PYTHON']
- 123. >>> s = [1, 2, 3, 4, 5, 6] >>> filter(lambda x: x % 2 == 0, s) [2, 4, 6] >>> s = ['C#', 'Java', 'Python' ] >>> map(lambda x: x.upper(), filter(lambda x: len(x) > 3, s)) ['JAVA', 'PYTHON']
- 124. >>> s = [3, 4, 5, 7, 9] >>> reduce(lambda x, y: x + y, s, 0) 28 >>> reduce( lambda x, y: x + (1 if (y % 2 == 0) else 0), s, 0) 1
- 125. >>> s = [3, 4, 5, 7, 9] >>> reduce(lambda x, y: x + y, s, 0) 28 >>> reduce( lambda x, y: x + (1 if (y % 2 == 0) else 0), s, 0) 1
- 126. >>> s = [3, 4, 5, 7, 9] >>> reduce(lambda x, y: x + y, s, 0) 28 >>> reduce( lambda x, y: x + (1 if (y % 2 == 0) else 0), s, 0) 1
- 127. >>> import itertools >>> s = ['a', 'b', 'c', 'd'] >>> zip(s, itertools.count()) [('a', 0), ('b', 1), ('c', 2), ('d', 3)] >>> filter(lambda x: x[1] != 1, zip(s, itertools.count())) [('a', 0), ('c', 2), ('d', 3)]
- 128. >>> import itertools >>> s = ['a', 'b', 'c', 'd'] >>> zip(s, itertools.count()) [('a', 0), ('b', 1), ('c', 2), ('d', 3)] >>> filter(lambda x: x[1] != 1, zip(s, itertools.count())) [('a', 0), ('c', 2), ('d', 3)]
- 129. >>> import itertools >>> s = ['a', 'b', 'c', 'd'] >>> zip(s, itertools.count()) [('a', 0), ('b', 1), ('c', 2), ('d', 3)] >>> filter(lambda x: x[1] != 1, zip(s, itertools.count())) [('a', 0), ('c', 2), ('d', 3)]
- 132. >>> [x for x in [1, 2, 3, 4, 5] if (x % 2 != 0)] [1, 3, 5] var l = from x in new List<int> { 1, 2, 3, 4, 5 } where x % 2 != 0 select x;
- 133. >>> [x * 2 for x in [1, 2, 3, 4, 5] if (x % 2 != 0)] [2, 6, 10] var l = from x in new List<int> { 1, 2, 3, 4, 5 } where x % 2 != 0 select x * 2;
- 135. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 136. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 137. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 138. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 139. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 140. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 141. def cor(f): i = 0 while True: i = f(i) yield i l = cor(lambda x: x + 4) [l.next() for x in range(0, 3)] [4, 8, 12]
- 142. IEnumerable<int> cor(Func<int, int> f) { int i = 0; while (true) { i = f(i); yield return i; } } var li = cor(x => x + 4); var ls = from x in li.Take(3) select "<" + x.ToString() + ">"; [“<4>”, “<8>”, “<12>”]
- 154. import static java.util.Arrays.asList; import static ch.lambdaj.Lambda.*; import static org.hamcrest.Matchers.*; selected = filter(greaterThan(3), asList(1, 2, 3, 4, 5)); [4, 5] List<String> fruits = asList("apple", "orange", "banana"); selected = filter(startsWith("a"), fruits); [“apple”]
- 155. import static java.util.Arrays.asList; import static ch.lambdaj.Lambda.*; import static org.hamcrest.Matchers.*; selected = filter(greaterThan(3), asList(1, 2, 3, 4, 5)); [4, 5] List<String> fruits = asList("apple", "orange", "banana"); selected = filter(startsWith("a"), fruits); [“apple”]
- 156. import static java.util.Arrays.asList; import static ch.lambdaj.Lambda.*; import static org.hamcrest.Matchers.*; selected = filter(greaterThan(3), asList(1, 2, 3, 4, 5)); [4, 5] List<String> fruits = asList("apple", "orange", "banana"); selected = filter(startsWith("a"), fruits); [“apple”]
- 157. import static java.util.Arrays.asList; import static ch.lambdaj.Lambda.*; import static org.hamcrest.Matchers.*; selected = filter(greaterThan(3), asList(1, 2, 3, 4, 5)); [4, 5] List<String> fruits = asList("apple", "orange", "banana"); selected = filter(startsWith("a"), fruits); [“apple”]
- 158. import static java.util.Arrays.asList; import static ch.lambdaj.Lambda.*; import static org.hamcrest.Matchers.*; selected = filter(greaterThan(3), asList(1, 2, 3, 4, 5)); [4, 5] List<String> fruits = asList("apple", "orange", "banana"); selected = filter(startsWith("a"), fruits); [“apple”]
- 159. selected = convert(fruits, new Converter<String, String>() { public String convert(String arg0) { return arg0.toUpperCase(); } }); [“APPLE”, “ORANGE”, “BANANA”] Closure c = closure(); { of(System.out).println(var(String.class)); } c.apply("foo"); c.each(fruits);
- 160. selected = convert(fruits, new Converter<String, String>() { public String convert(String arg0) { return arg0.toUpperCase(); } }); [“APPLE”, “ORANGE”, “BANANA”] Closure c = closure(); { of(System.out).println(var(String.class)); } c.apply("foo"); c.each(fruits);
- 161. selected = convert(fruits, new Converter<String, String>() { public String convert(String arg0) { return arg0.toUpperCase(); } }); [“APPLE”, “ORANGE”, “BANANA”] Closure c = closure(); { of(System.out).println(var(String.class)); } c.apply("foo"); c.each(fruits);
- 162. selected = convert(fruits, new Converter<String, String>() { public String convert(String arg0) { return arg0.toUpperCase(); } }); [“APPLE”, “ORANGE”, “BANANA”] Closure c = closure(); { of(System.out).println(var(String.class)); } c.apply("foo"); c.each(fruits);
- 163. selected = convert(fruits, new Converter<String, String>() { public String convert(String arg0) { return arg0.toUpperCase(); } }); [“APPLE”, “ORANGE”, “BANANA”] Closure c = closure(); { of(System.out).println(var(String.class)); } c.apply("foo"); c.each(fruits);
- 165. import static fj.data.Array.*; import static fj.function.Integers.*; import fj.data.Array; Array<Integer> a = array(1, 2, 3, 4, 5, 6); Array<Integer> b = a.filter(even).map(add.f(10)); [12, 14, 16]
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