funcy

Description:

funcy

Utility classes and functions for comfortable and "safe" functional programming.
Usage #
A simple usage example:
import 'package:funcy/funcy.dart';
import 'package:meta/meta.dart';

void main() {
final employeeJson = retrieveEmployeeJson();
final maybeEmployee =
Employee.tryFromJson(employeeJson) | tryFallbackEmployee();
maybeEmployee.option(
() => print('Something really bad is happening '
'even fallback employee does not work.'),
(employee) => print('${employee.name} is ${employee.age}.'),
);
}

Map<String, dynamic> retrieveEmployeeJson() => <String, dynamic>{
'name': 'Bob',
'position': 'boss',
'age': 42,
};

Option<Employee> tryFallbackEmployee() => Some(
Employee(
name: 'Fallback Employee',
position: Position.subsubboss,
age: -1,
),
);

enum Position {
boss,
subboss,
subsubboss,
}

Option<Position> tryParsePosition(String positionStr) {
switch (positionStr) {
case 'boss':
return const Some(Position.boss);
case 'subboss':
return const Some(Position.subboss);
case 'subsubboss':
return const Some(Position.subsubboss);
default:
return const None();
}
}

class Employee {
Employee({
@required this.name,
@required this.position,
@required this.age,
});

final String name;
final Position position;
final int age;

static Option<Employee> tryFromJson(Map<String, dynamic> json) {
return json.tryGet<String>('name').bind(
(name) {
return json.tryGet<String>('position').bind(tryParsePosition).bind(
(position) {
return json.tryGet<int>('age').guard(_ageTest).map(
(age) {
return Employee(
name: name,
position: position,
age: age,
);
},
);
},
);
},
);
}

static bool _ageTest(int age) => age >= 18;
}
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