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https://github.com/ghurtchu/fluentry
:policeman::oncoming_police_car: Manage unchecked exceptions functionally.
https://github.com/ghurtchu/fluentry
abstraction composition declarative-programming functional-programming java monad reflection stack-safe
Last synced: 3 months ago
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:policeman::oncoming_police_car: Manage unchecked exceptions functionally.
- Host: GitHub
- URL: https://github.com/ghurtchu/fluentry
- Owner: Ghurtchu
- Created: 2022-09-17T11:41:04.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2023-04-07T07:50:38.000Z (almost 2 years ago)
- Last Synced: 2023-12-08T00:08:53.057Z (about 1 year ago)
- Topics: abstraction, composition, declarative-programming, functional-programming, java, monad, reflection, stack-safe
- Language: Java
- Homepage:
- Size: 169 KB
- Stars: 10
- Watchers: 3
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
#### An attempt to port `scala.util.Try` to Java.
The main class is called `Try`.
`Try` has a few overloaded static constructors for instantiating lazy computations which is called `Try.of()`.
`Try` instance may be constructed via one of these five arguments:
- `Runnable`
- `Consumer with arg`,
- `Supplier`,
- `Function with arg`,
- `BiFunction with two args`
`Try` has two sub-classes: `Success` which holds the successful value and `Failure` which holds the exception.
`Try` may be used in different ways, so without further ado let's see the examples below:
problem description: try getting the element from the list, if it fails return stringified 0, or else return the stringified square of the success value.
solution with pure java:
```java
public static String getAndThenDoubleAndThenStringify(List list, int index) {
String result;
try {
int number = list.get(index);
result = String.valueOf(number * 2);
} catch (Exception e) {
result = "0";
}
return result;
}
```
solution with `fluenTry`:
```java
public static String getAndThenDoubleAndThenStringify(List list, int index) {
return Try.of(list, index, List::get).map(n -> n * 2).fold(String::valueOf, "0");
}
```
Here is a Failed computation which returns `Failure(ArithmeticException)` instead of blowing up the calling stack by throwing an exception and succeeds with pure value with the help of `fold` combinator:
```java
double result = Try.of(() -> Math.random() * 2 * 5)
.flatMap(n -> Try.of(() -> n + 1))
.flatMap(n -> Try.of(() -> 55 / 0)) // This is where the `Success` turns into `Failure`
.map(Math::sqrt)
.fold(Function.identity(), 0.0); // but with the help of `fold` we turn that into pure value
```
Let's see another example:
problem description: try to parse json string into `Person` instance, if succeeds return true or else return false.
solution with pure java:
```java
public static Optional parseJson(String json) {
var jsonParser = new JsonParser();
Optional result;
try {
result = Optional.of(jsonParser.fromJson(json));
} catch (JsonParsingException jpe) {
result = Optional.empty();
}
return result;
}
```
solution with `fluenTry` - takes a string argument and the `Function` instance as a second argument, finally calles `toOptional()` which converts the `Try` into `Optional`:
```java
public static Optional parseJson(String json) {
var parser = new JsonParser();
return Try.of(json, parser::fromJson).toOptional();
}
```
Let's see something related to java Enums:
problem description: Write a method on Weekend enum which returns true of the passed string is a Weekend day or else return false.
solution with pure java:
```java
public enum Weekend {
SATURDAY,
SUNDAY;
public static boolean isWeekend(String day) {
try {
String normalized = day.trim().toUpperCase();
Weekend.valueOf(normalized);
return true;
} catch (IllegalArgumentException iae) {
return false;
}
}
}
```
with `fluenTry:` - takes a `Supplier` as an argument, then `maps` and finally `folds` to either `true` or `false`:
```java
public enum Weekend {
SATURDAY,
SUNDAY;
public static boolean isWeekend(String day) {
return Try.of(() -> day.trim().toUpperCase()).map(Weekend::valueOf).fold(d -> true, false);
}
}
```