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Update README with more examples for Result and updated badges

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Paul Campbell 2018-06-22 23:17:42 +01:00
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README.md
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@ -1,13 +1,19 @@
Mon Mon
=== ===
TypeAlias for Java TypeAlias, Maybe and Result for Java
[![GitHub release](https://img.shields.io/github/release/kemitix/mon.svg)]() [![Sonatype Nexus (Releases)](https://img.shields.io/nexus/r/https/oss.sonatype.org/net.kemitix/mon.svg?style=for-the-badge)](https://oss.sonatype.org/content/repositories/releases/net/kemitix/mon/)
[![Codacy Badge](https://api.codacy.com/project/badge/Grade/d57096b0639d496aba9a7e43e7cf5b4c)](https://www.codacy.com/app/kemitix/mon?utm_source=github.com&utm_medium=referral&utm_content=kemitix/mon&utm_campaign=Badge_Grade) [![Maven Central](https://img.shields.io/maven-central/v/net.kemitix/mon.svg?style=for-the-badge)](https://search.maven.org/#search|ga|1|g%3A"net.kemitix"%20AND%20a%3A"mon")
[![Build Status](https://travis-ci.org/kemitix/mon.svg?branch=master)](https://travis-ci.org/kemitix/mon)
[![Coverage Status](https://coveralls.io/repos/github/kemitix/mon/badge.svg?branch=master)](https://coveralls.io/github/kemitix/mon?branch=master) [![SonarQube Coverage](https://img.shields.io/sonar/https/sonarcloud.io/net.kemitix%3Amon/coverage.svg?style=for-the-badge)](https://sonarcloud.io/dashboard?id=net.kemitix%3Amon)
[![codecov](https://codecov.io/gh/kemitix/mon/branch/master/graph/badge.svg)](https://codecov.io/gh/kemitix/mon) [![SonarQube Tech Debt](https://img.shields.io/sonar/https/sonarcloud.io/net.kemitix%3Amon/tech_debt.svg?style=for-the-badge)](https://sonarcloud.io/dashboard?id=net.kemitix%3Amon)
[![Jenkins](https://img.shields.io/jenkins/s/https/jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon.svg?style=for-the-badge)](https://jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon/)
[![Jenkins tests](https://img.shields.io/jenkins/t/https/jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon.svg?style=for-the-badge)](https://jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon/)
[![Jenkins coverage](https://img.shields.io/jenkins/c/https/jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon.svg?style=for-the-badge)](https://jenkins.kemitix.net/job/GitLab/job/kemitix%252Fmon/)
[![Codacy grade](https://img.shields.io/codacy/grade/d57096b0639d496aba9a7e43e7cf5b4c.svg?style=for-the-badge)](https://app.codacy.com/project/kemitix/mon/dashboard)
## Maven ## Maven
@ -15,7 +21,7 @@ TypeAlias for Java
<dependency> <dependency>
<groupId>net.kemitix</groupId> <groupId>net.kemitix</groupId>
<artifactId>mon</artifactId> <artifactId>mon</artifactId>
<version>0.4.0</version> <version>0.6.0</version>
</dependency> </dependency>
``` ```
@ -23,6 +29,8 @@ TypeAlias for Java
### TypeAlias ### TypeAlias
More of a type-wrapper really. It's as close as I could get to a Haskell type alias in Java.
```java ```java
class Goal extends TypeAlias<String> { class Goal extends TypeAlias<String> {
private Goal(final String goal) { private Goal(final String goal) {
@ -35,34 +43,32 @@ class Goal extends TypeAlias<String> {
``` ```
```java ```java
class Example {}
Goal goal = Goal.of("goal"); Goal goal = Goal.of("goal");
void foo(final Goal goal) { void foo(final Goal goal) {
System.out.println("The goal is " + goal.getValue()); System.out.println("The goal is " + goal.getValue());
} }
}
``` ```
### Maybe (Just & Nothing) ### Maybe
A non-final substitute for Optional with `peek()` and `stream()` methods.
```java ```java
class Test {
@Test
public void maybeTests() {
assertThat(Maybe.maybe(null)).isEqualTo(Maybe.nothing()); assertThat(Maybe.maybe(null)).isEqualTo(Maybe.nothing());
assertThat(Maybe.maybe(1)).isEqualTo(Maybe.just(1)); assertThat(Maybe.maybe(1)).isEqualTo(Maybe.just(1));
assertThat(Maybe.nothing() assertThat(Maybe.nothing().orElseGet(() -> 1)).isEqualTo(1);
.orElseGet(() -> 1)).isEqualTo(1); assertThat(Maybe.just(1).orElseGet(() -> 2)).isEqualTo(1);
assertThat(Maybe.just(1) assertThat(Maybe.nothing().orElse(1)).isEqualTo(1);
.orElseGet(() -> 2)).isEqualTo(1); assertThat(Maybe.just(1).orElse(2)).isEqualTo(1);
assertThat(Maybe.nothing() assertThat(Maybe.just(1).filter(v -> v > 2)).isEqualTo(Maybe.nothing());
.orElse(1)).isEqualTo(1); assertThat(Maybe.just(3).filter(v -> v > 2)).isEqualTo(Maybe.just(3));
assertThat(Maybe.just(1) assertThat(Maybe.just(1).toOptional()).isEqualTo(Optional.of(1));
.orElse(2)).isEqualTo(1); assertThat(Maybe.nothing().toOptional()).isEqualTo(Optional.empty());
assertThat(Maybe.just(1)
.filter(v -> v > 2)).isEqualTo(Maybe.nothing());
assertThat(Maybe.just(3)
.filter(v -> v > 2)).isEqualTo(Maybe.just(3));
assertThat(Maybe.just(1)
.toOptional()).isEqualTo(Optional.of(1));
assertThat(Maybe.nothing()
.toOptional()).isEqualTo(Optional.empty());
assertThat(Maybe.fromOptional(Optional.of(1))).isEqualTo(Maybe.just(1)); assertThat(Maybe.fromOptional(Optional.of(1))).isEqualTo(Maybe.just(1));
assertThat(Maybe.fromOptional(Optional.empty())).isEqualTo(Maybe.nothing()); assertThat(Maybe.fromOptional(Optional.empty())).isEqualTo(Maybe.nothing());
final AtomicInteger reference = new AtomicInteger(0); final AtomicInteger reference = new AtomicInteger(0);
@ -70,8 +76,114 @@ assertThat(Maybe.just(1).peek(reference::set)).isEqualTo(Maybe.just(1));
assertThat(reference).hasValue(1); assertThat(reference).hasValue(1);
assertThat(Maybe.nothing().peek(v -> reference.incrementAndGet())).isEqualTo(Maybe.nothing()); assertThat(Maybe.nothing().peek(v -> reference.incrementAndGet())).isEqualTo(Maybe.nothing());
assertThat(reference).hasValue(1); assertThat(reference).hasValue(1);
assertThatCode(() -> Maybe.just(1).orElseThrow(IllegalStateException::new)) assertThatCode(() -> Maybe.just(1).orElseThrow(IllegalStateException::new)).doesNotThrowAnyException();
.doesNotThrowAnyException(); assertThatThrownBy(() -> Maybe.nothing().orElseThrow(IllegalStateException::new)).isInstanceOf(IllegalStateException.class);
assertThatThrownBy(() -> Maybe.nothing().orElseThrow(IllegalStateException::new)) assertThat(Maybe.just(1).stream()).containsExactly(1);
.isInstanceOf(IllegalStateException.class); assertThat(Maybe.nothing().stream()).isEmpty();
}
}
```
### Result
A container for method return values that may raise an Exception. Useful for when a checked exceptions can't be added
to the method signature.
```java
package net.kemitix.mon;
import net.kemitix.mon.result.Result;
import java.io.IOException;
class ResultExample implements Runnable {
public static void main(String[] args) {
new ResultExample().run();
}
@Override
public void run() {
System.out.println("run");
final Result<Integer> goodResult = goodMethod();
if (goodResult.isOkay()) {
doGoodThings();
}
if (goodResult.isError()) {
notCalled(0);
}
goodResult.flatMap(number -> convertToString(number))
.flatMap(str -> stringLength(str))
.match(
success -> System.out.format("Length is %s%n", success),
error -> System.out.println("Count not determine length")
);
final Result<Integer> badResult = badMethod();
badResult.match(
success -> notCalled(success),
error -> handleError(error)
);
}
private Result<Integer> goodMethod() {
System.out.println("goodMethod");
return Result.ok(1);
}
private void doGoodThings() {
System.out.println("doGoodThings");
}
private void notCalled(final Integer success) {
System.out.println("notCalled");
}
private Result<String> convertToString(final Integer number) {
System.out.println("convertToString");
return Result.ok(String.valueOf(number));
}
private Result<Integer> stringLength(final String value) {
System.out.println("stringLength");
if (value == null) {
return Result.error(new NullPointerException("value is null"));
}
return Result.ok(value.length());
}
// doesn't need to declare "throws IOException"
private Result<Integer> badMethod() {
System.out.println("badMethod");
return Result.error(new IOException("error"));
}
private void handleError(final Throwable error) {
System.out.println("handleError");
throw new RuntimeException("Handled exception", error);
}
}
```
Will output:
```text
run
goodMethod
doGoodThings
convertToString
stringLength
Length is 1
badMethod
handleError
Exception in thread "main" java.lang.RuntimeException: Handled exception
at net.kemitix.mon.ResultExample.handleError(ResultExample.java:72)
at net.kemitix.mon.ResultExample.lambda$run$5(ResultExample.java:34)
at net.kemitix.mon.result.Err.match(Err.java:56)
at net.kemitix.mon.ResultExample.run(ResultExample.java:32)
at net.kemitix.mon.ResultExample.main(ResultExample.java:10)
Caused by: java.io.IOException: error
at net.kemitix.mon.ResultExample.badMethod(ResultExample.java:67)
at net.kemitix.mon.ResultExample.run(ResultExample.java:31)
... 1 more
``` ```