文件列表:

CHANGELOG.md (449, 2022-03-20)
LICENSE (1069, 2022-03-20)
analysis_options.yaml (47, 2022-03-20)
example/ (0, 2022-03-20)
example/CHANGELOG.md (29, 2022-03-20)
example/analysis_options.yaml (438, 2022-03-20)
example/bin/ (0, 2022-03-20)
example/bin/example.dart (854, 2022-03-20)
example/lib/ (0, 2022-03-20)
example/lib/example.dart (1851, 2022-03-20)
example/pubspec.lock (401, 2022-03-20)
example/pubspec.yaml (263, 2022-03-20)
lib/ (0, 2022-03-20)
lib/pure.dart (933, 2022-03-20)
lib/src/ (0, 2022-03-20)
lib/src/common/ (0, 2022-03-20)
lib/src/common/curried_function_types.dart (1852, 2022-03-20)
lib/src/common/function_types.dart (1481, 2022-03-20)
lib/src/composition/ (0, 2022-03-20)
lib/src/composition/dot.dart (269, 2022-03-20)
lib/src/composition/pipe.dart (367, 2022-03-20)
lib/src/constant/ (0, 2022-03-20)
lib/src/constant/extensions.dart (263, 2022-03-20)
lib/src/curry/ (0, 2022-03-20)
lib/src/curry/extensions.dart (2275, 2022-03-20)
lib/src/flip/ (0, 2022-03-20)
lib/src/flip/extensions.dart (1693, 2022-03-20)
lib/src/functions/ (0, 2022-03-20)
lib/src/functions/functions.dart (918, 2022-03-20)
lib/src/memoization/ (0, 2022-03-20)
lib/src/memoization/extensions.dart (3247, 2022-03-20)
lib/src/memoization/helpers.dart (410, 2022-03-20)
lib/src/nullable/ (0, 2022-03-20)
lib/src/nullable/extensions.dart (3055, 2022-03-20)
lib/src/partial_application/ (0, 2022-03-20)
lib/src/partial_application/extensions.dart (2205, 2022-03-20)
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# Pure Pure is a Dart package that brings functional programming essentials through extension methods. It offers function composition/pipes, function memoization, partial application, and recursion trampolines. ## Extensions Down are listed extensions included in the `pure` package. Every extension is valid from 0/1 arguments up to 9 arguments. ### Composition Provides function composition functionality. Substituting function application with composition or pipes helps to make code more readable and reduces nesting. ```dart double intToDouble(int x) => x.toDouble(); String doubleToString(double x) => x.toString(); /// Traditional application String intToStringApplication(int x) => doubleToString(intToDouble(x)); /// Composition final intToStringComposition = doubleToString.dot(intToDouble); /// Pipes String intToStringPipe1(int x) => x.pipe(intToDouble).pipe(doubleToString); // or String intToStringPipe2(int x) => intToDouble(x).pipe(doubleToString); ``` ### Constant Allows to create a function from a single value that discards its only argument and returns the value. For example, can be used to map a list of numbers to a single number. ```dart const numbers = [1, 2, 3]; final zeros = numbers.map(0.constant); /// Equivalent to `numbers.map((number) => 0);` ``` ### Curry and Uncurry Allows to curry an uncurried function and uncurry a curried function. Currying is a process of transforming a function that takes multiple arguments into a chain of functions that take a single argument and returns another function, as many times as there were arguments in the original function. ```dart String createPerson(String country, int age, String name) => "$country, $name, $age"; final createTwin = createPerson.curry("Canada")(12); final tim = createTwin("Tim"); final jim = createTwin("Jim"); ``` ### Flipping Allows to flip the arguments, reversing their order. ```dart String createPerson(String firstName, String lastName) => "$firstName, $lastName"; final createFormalPerson = createPerson.flip; print(createFormalPerson('John', 'Doe')); /// Prints "Doe, John". ``` ### Nullable invocation Allows to call a function that normally takes non-nullable arguments with nullable ones and runs it only when all arguments are not null indeed. ```dart int sum(int first, int second) => first + second; final sumNullable = sum.nullable; print(sumNullable(2, 2)); /// Prints "4" print(sumNullable(2, null)); /// Prints "null" ``` ### Recursion Trampolines Provides stack-safe recursion functionality. Trampolines essentially do the same work as compiler's tail call optimization – flatten the stack of calls, making function never exceeding stack and never resulting in Stack Overflow. ```dart /// Regular int regularSum(int number, int sum) => number == 0 ? sum : regularSum(number - 1, sum + number); /// Trampolined Tram tramSum(int number, int sum) => number == 0 ? Tram.done(sum) : Tram.call(() => tramSum(number - 1, sum + number)); final n = 99999999; final trampolined1 = tramSum.bounce(n, 0); // 4999999950000000 // or final trampolined12 = tramSum(n, 0).bounce(); // 4999999950000000 final regular = regularSum(n, 0); // Unhandled exception: Stack Overflow ``` ### Memoization Provides hash-based memoization functionality. Allows to perform optimization and perform actual computations only when inputs given to the function are given for the first time. It is highly discouraged to use memoization on impure functions, mainly because it does not make very much sense. Below, memoization is used on an impure function only for demonstrational purposes. ```dart int Function(int base) newCounter() { var counter = 0; return (base) => base + counter++; } final counter = newCounter().memoize(); counter(0); // Returns 0, counter becomes 1 counter(10); // Returns 11, counter becomes 2 counter(0); // Returns 0, counter stays 2 counter(11); // Returns 13, counter becomes 3 ``` ### Partial Application Provides non-curried function partial application. Existing ways do so through creating a function buffer or through currying, applying arguments, and uncurrying the function back. This approach eliminates the need for two intermediate steps and allows application arguments directly. ```dart int sumThree(int a, int b, int c) => a + b + c; int buffer(int b, int c) => sumThree(1, b, c); final partial = sumThree.apply(1); ```

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