try-monad

About

Inspired by scala.util.Try, this is small library that provides an abstraction of result of a function application.

API Docs

https://jecklgamis.github.io/try-monad/apidocs/

Getting Started

Maven

<dependency>
    <groupId>com.jecklgamis</groupId>
    <artifactId>try-monad</artifactId>
    <version>1.0</version>
</dependency>

Gradle

compile 'com.jecklgamis:try-monad:1.0'

Apache Buildr

'com.jecklgamis:try-monad:jar:1.0'

Groovy Grapes

@Grapes(
@Grab(group='com.jecklgamis', module='try-monad', version='1.0')
)

Leiningen

[com.jecklgamis/try-monad "1.0"]

A Primer On Using Try

Below is an example util function to check socket connection to a specified host.

import java.io.IOException;
import java.net.Socket;

import static com.jecklgamis.util.TryFactory.attempt;

public class ExampleUsage {

    public static boolean canConnect(String host, int port) {
        return attempt(() -> new Socket(host, port)).map((s) -> s.isConnected()).getOrElse(false);
    }

    public static void main(String[] args) {
        System.out.println(canConnect("localhost", 80));
    }
}

The canConnect function uses TryFactory.attempt (similar to try) to invoke a function that returns a socket instance (() → new Socket). It will then return an instance of Try , specifically a Success if there is no exception thrown, or Failure otherwise.

If the call is successful, the function passed to map (i.e. (s) → s.isConnected()) will be invoked. The s parameter in the expression is the result of function in attempt (a socket instance). If attempt fails (attempt returned a Failure), map will not be invoked and simply returns the Failure returned by attempt.

The last call in the chain is getOrElse(false), which will return a boolean depending on the output of map. If the map returns a Success (no exception thrown in (s)→ s.isConnected), `getOrElse will simply return the value of the function passed to map. Otherwise, getOrElse will return the given value, which in this case false.