flechette
This package includes
- general purpose helper classes such as tuple, result.
- Scala-like collection APIs. e.g.
groupBy,zipWithIndex,sliding(n),fold
flechette/struct
Result: Result<T>
final success = Result.success(1);
final failure = Result<T>.failure('error key','error message');
success.isSuccess // => true;
failure.isSuccess // => false;
success.map((s)=>s*2); // => Result.success(2);
success.flatMap((s) => Result.success('100') )// => Result.success('100');
success.flatMap((s) => Result.failure(...)) // => Result.failure(...);
Tuple: $(a,b)
final tpl = $(1,'a'); // create tuple
tpl.$0 // => 1
tpl.$1 // => 'a'
tpl.swap(); // => $('a',1);
tpl.mapN((l,r) => T ); // => T
flechette/syntax
Collection/Iterable
final l = [1,2,3,4,5];
l.zipWithIndex // => [(1,0),(2,1),(3,2),(4,3),(5,4)]
l.slide // => [(1,2),(2,3),(3,4),(4,5)]
[1,2,3,4,5,6,7].sliding(4) // => [[1,2,3,4],[2,3,4,5],[3,4,5,6],[4,5,6,7]];
l.zip(['a','b','c','d','e']); // => [(1,'a'),(2,'b'),(3,'c'),(4,'d'),(5,'e')]
l.intersect(-1) // => [1,-1,2,-1,3,-1,4,-1,5];
flatmap(iterable)
import 'package:flechette/syntax/flatmap_iterable.dart';
final l = [1,2,3,4,5].flatMap((e) => Iterable<int>.generate(e) ); // => [0,0,1,0,1,2,...];
Collection/Map
final map = {'a':1,'b':2,'c':3};
map.updateWith(key)((v) => v == null ? 'newItem' : '$v already exists');
Optional
final T? t = ???;
t
.map((a)=> b)
.filter((b)=> cond(b) )
.getOrElse(()=>els);
const int? a = 1;
const int? b = null;
a.fold(() => 'none!')((e) => (e * 100).toString()); // => '100'
b.fold(() => 'none!')((e) => (e * 100).toString()); // => 'none!'
import 'package:flechette/syntax/flatmap_optional.dart';
[1,2,3,4,5,6,7,8,9,10].flatMap((e) => e %2 == 0 ? e : null); // [2,4,6,8,10];
dart/core
DateTimeX.attemptParse('...'); // => Result<DateTime>
UriX.attemptParse('...'); // => Result<DateTime>