loda

Description:

loda

Features #
Functional programming in Dart and Flutter.
Getting started #
The loda module is a combination of the two Lodash and Ramda modules. It promotes a more functional programming (FP) friendly style by exporting an instance of loda with its methods wrapped to produce immutable auto-curried iteratee-first data-last methods.
Usage #
install
# pubspec.yaml
dependencies:
loda: ^1.0.2
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Ex 1:
import 'package:loda/loda.dart';

const _ = LodaConstants.placeholder;

final profiles = [
{
"name": "John",
"age": 19,
"address": {
"country": "DN",
},
},
{
"name": "Michel",
"age": 18,
"address": {
"country": "QN",
},
},
{
"name": "Cel",
"age": 17,
"address": {
"country": 'ĐL',
},
},
];
final bool Function(dynamic) isEligible = and([
has('name'),
has('age'),
flow([
select('age'),
gte(_, 18),
]),
]);
final getCountriesOfEligibleProfiles = flow([
filter(isEligible),
map(select('address.country')),
distinct,
]);
final countries = getCountriesOfEligibleProfiles(profiles);
print(countries); // [DN, QN]
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Ex 2:
import 'package:loda/loda.dart';
import 'package:collection/collection.dart';

final profiles = [
{
"id": "1",
"address": {
"city": "DN",
},
"name": "Duy Nguyen",
},
{
"id": "2",
"name": "Minh D",
"address": {
"city": "DL",
}
},
{
"id": "3",
"name": 'Monad',
"address": {
"city": null,
}
}
];
Maybe<Map> findMaybe(List<Map>? entries, id) {
final result = entries?.firstWhereOrNull(
(obj) => obj["id"] == id,
);
return (result?.isNotEmpty ?? false)
? Maybe.some(result)
: Maybe.nothing();
}

Function get = curry(
(key, obj) =>
obj.containsKey(key) ? Maybe.some(obj[key]) : Maybe.nothing(),
);

toLowerCase(String str) => str.toLowerCase();

findProfileWithId(id) => findMaybe(profiles, id)
.flatMap(get("address"))
.flatMap(get("city"))
.map(toLowerCase)
.unwrap();

print(findProfileWithId("1")); // dn

print(findProfileWithId("3")); // null
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Additional information #
My article introduces to Functional Programming
LINK