Update example and CHANGELOG

CHANGELOG.md

@@ -1,3 +1,17 @@
+## [0.3.0] - 03.05.2022
+
+Added new methods to `Option` and `Result`.
+
+Option:
+
+- `flatMap` - returns None or calls `f` with the wrapped value and returns `Some(f(value))`;
+- `filter` - returns None if the option is None or predicate returns false, otherwise returns Some.
+
+Result:
+
+- `flatMap` - calls `f` if the result is `Ok`, otherwise returns the `Err` value of self;
+- `flatMapErr` - Calls `f` if the result is `Err`, otherwise returns the `Ok` value of self.
+
 ## [0.2.1] - 31.05.2022
 
 Restricted the parameterized type E for tryCatch and asyncTryCatch.

example/example.dart

@@ -4,13 +4,12 @@ import 'dart:math';
 import 'package:dfp/dfp.dart';
 
 void main() async {
-  final str = Option.fromNullable(stdin.readLineSync());
-  final number = Option.flatten(
-    str.map((value) => Option.fromNullable(double.tryParse(value))),
-  );
-  final fixed = number
+  final number = fromNullable(stdin.readLineSync())
+      .flatMap((value) => fromNullable(double.tryParse(value)))
       .map(sin)
+      .filter((value) => value >= 0)
       .map((value) => value * 2)
       .map((value) => value.abs().toStringAsFixed(2));
-  print(fixed.toNullable());
+
+  print(number.toNullable());
 }

pubspec.yaml

@@ -1,6 +1,6 @@
 name: dfp
 description: A library for typed functional programming in Dart, inspired by Rust.
-version: 0.2.1
+version: 0.3.0
 repository: https://github.com/san-smith/dfp
 
 environment: