Added documentation and CI support

.gitea/workflows/LambdaTonic.yml

@@ -0,0 +1,19 @@
+name: LambdaTonic
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-java@v4
+        with:
+          distribution: "corretto"
+          java-version: "22"
+      - name: Execute unit tests with Maven
+        run: |
+          sed -i 's/\r$//' mvnw
+          ./mvnw test

.github/workflows/LambdaTonic.yml

@@ -0,0 +1,19 @@
+name: LambdaTonic
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-java@v4
+        with:
+          distribution: "corretto"
+          java-version: "22"
+      - name: Execute unit tests with Maven
+        run: |
+          sed -i 's/\r$//' mvnw
+          ./mvnw test

.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,19 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+wrapperVersion=3.3.2
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2024 Cetica Marco
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,297 @@
+# λTonic 🥃 ![](https://github.com/ceticamarco/lambdatonic/actions/workflows/LambdaTonic.yml/badge.svg)
+
+**λTonic**(_LambdaTonic_) is functional library designed for modern Java(+21).  
+
+This library introduces a new algebraic data type called `Either<L, R>`; 
+that is, an immutable  sum type that _discriminates_ between two values, `Left<L>` and `Right<R>`, 
+representing the failure and the success values, respectively.
+
+The `Either<L, R>` data type is implemented using a **sealed interface**, while the `Left<LL>`
+and the `Right<R>` are **record classes** that adopt the `Either<L, R>` protocol. Both the `Left<L>`
+and the `Right<R>` data types can be used inside a `switch` statement using Java pattern matching. 
+
+## Overview
+The `Either<L, R>` algebraic data type can be used orthogonally over exceptions to propagate
+an error from a function. Consider the following scenario:
+```java
+public class Main {
+    public static Either<Error, Double> division(double dividend, double divisor) {
+        // Return an error whether the divisor is zero
+        if(divisor == 0) {
+            return new Left<>(new Error("Cannot divide by zero"));
+        }
+
+        // Otherwise return the result of the division
+        return new Right<>(dividend / divisor);
+    }
+
+    public static void main(String[] args) {
+        // Try to divide 15 by 3
+        Either<Error, Double> divResult = division(15, 3);
+        switch (divResult) {
+            case Left<Error, Double> err -> System.err.println(err.value().getMessage());
+            case Right<Error, Double> val -> System.out.printf("15 / 3 = %f\n", val.value());
+        }
+
+        // Try to divide 2 by 0
+        var div2Result = division(2, 0);
+        switch (div2Result) {
+            case Left<Error, Double> err -> System.err.println(err.value().getMessage());
+            case Right<Error, Double> val -> System.out.printf("2 / 0 = %f\n", val.value());
+        }
+    }
+}
+```
+
+In this example we have defined a `division` method that takes two arguments and perform a division
+on them. To handle the case when the `divisor` parameter is equal to zero, we return a new `Left<L>`
+instance of the `Either<L, R>` type, while in any other case, we return a new `Right<R>` instance of the
+`Either<L, R>` type. In the caller method(i.e., the `main`) we can then execute a custom statement using 
+Java's builtin pattern matching.
+
+## API Usage
+The `Either<L, R>` data type supports a broad spectrum of features, below there is a list of all supported
+functionalities.
+
+-  `map`
+
+### Description
+```java
+<T> Either<L, T> map(Function<R, T> fn);
+```
+The `map` method applies a function(`fn`) to the values inside the data type,
+returning a new data type if and only if the `Either<L, R>` type is instantiated
+to the `Right<R>` type. The `map` method adheres to the 
+functor laws(identity and composition of morphisms), which allows the `Either<L, R>` data type
+to be classified as a functor.
+
+### Usage
+The `map` method can be used to apply a computation to the value inside a functor:
+```java
+public class Main {
+    // ...
+    public static void main(String[] args) {
+        var resDivision = division(15, 3);
+        var resSquared = resDivision.map(x -> x * x);
+
+        switch (resSquared) {
+            case Left<Error, Double> err -> System.err.println(err.value().getMessage());
+            case Right<Error, Double> val -> System.out.println(val.value()); // prints 25.0
+        }
+    }
+}
+```
+
+- `bimap`
+
+### Description
+```java
+<T, K> Either<T, K> bimap(Function<L, T> onLeft, Function<R, K> onRight);
+```
+
+The `bimap` method applies the `onLeft` method to the `Left<L>` subtype or the
+`onRight` to the `Right<R>`.
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input);
+
+        // Apply a function regardless of the type of Either
+        // On the left we uppercase the error message
+        // On the right we square the result
+        var bimapRes = divRes.bimap(
+            err -> new Error(err.toString().toUpperCase()),
+            val -> val * val
+        );
+
+        switch (bimapRes) {
+            case Left<Error, Double> err -> System.err.println(err.value().getMessage());
+            case Right<Error, Double> val -> System.out.println(val.value());
+        }
+    }
+}
+```
+
+- `isLeft`
+
+### Description
+```java
+boolean isLeft();
+```
+
+`isLeft` returns true whether `Either<L, R>` is instantiated to the `Left<L>`, false otherwise
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input);
+        
+        if(divRes.isLeft()) {
+            System.out.println("Cannot divide by zero");
+        } else {
+            System.out.println(divRes.fromRight(-1.0));
+        }
+    }
+}
+```
+
+- `isRight`
+
+### Description
+```java
+boolean isRight();
+```
+
+`isRight` returns true whether `Either<L, R>` is instantiated to the `Right<L>`, false otherwise
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input);
+
+        if(divRes.isRight()) {
+            System.out.println(divRes.fromRight(-1.0));
+        } else {
+            System.out.println("Cannot divide by zero");
+        }
+    }
+}
+```
+
+- `fromLeft`
+
+### Description
+```java
+L fromLeft(L defaultValue);
+```
+
+`fromLeft` returns the content of the `Left<L>` value or a default value
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input);
+        
+        // Prints out the error message or nothing  
+        System.out.println(divRes.fromLeft(new Error("")).getMessage());
+    }
+}
+```
+
+- `fromRight`
+
+### Description
+```java
+L fromLeft(L defaultValue);
+```
+
+`fromRight` returns the content of the `Right<R>` value or a default value
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input);
+
+        // Prints out the actual value or nothing
+        System.out.println(divRes.fromRight(0.0));
+    }
+}
+```
+
+- `toOptional`
+
+### Description
+```java
+Optional<R> toOptional();
+```
+
+`toOptional` converts an `Either<L, R>` data type to a `java.util.Optional`,
+where the `Right<R>` becomes a non-null `Optional<R>` and the `Left<L>`
+becomes a null `Optional`.
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        var sc = new Scanner(System.in);
+
+        // Read from stdin
+        System.out.print("Enter a divisor: ");
+        var input = sc.nextInt();
+
+        // Divide a fixed dividend by user input divisor
+        var divRes = division(15, input).toOptional();
+
+        // Prints out the actual value or nothing
+        divRes.ifPresent(System.out::println);
+    }
+}
+```
+
+- `swap`
+
+### Description
+```java
+Either<R, L> swap();
+```
+
+`swap` returns an `Either<R, L>` type with `Left<R>` and `Right<L>` swapped.
+
+### Usage
+```java
+public class Main {
+    public static void main(String[] args) {
+        Either<String, Integer> val = new Left<>("generic error");
+        Either<Integer, String> res = val.swap();
+
+        System.out.println(res.isLeft()); // Prints false
+        System.out.println(res.isRight()); // Prints true
+    }
+}
+```
+
+## License
+This software is released under the MIT license. 
+You can find a copy of the license with this repository or by visiting 
+the [following page](https://choosealicense.com/licenses/mit/).

mvnw

@@ -0,0 +1,259 @@
+#!/bin/sh
+# ----------------------------------------------------------------------------
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+# ----------------------------------------------------------------------------
+
+# ----------------------------------------------------------------------------
+# Apache Maven Wrapper startup batch script, version 3.3.2
+#
+# Optional ENV vars
+# -----------------
+#   JAVA_HOME - location of a JDK home dir, required when download maven via java source
+#   MVNW_REPOURL - repo url base for downloading maven distribution
+#   MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
+#   MVNW_VERBOSE - true: enable verbose log; debug: trace the mvnw script; others: silence the output
+# ----------------------------------------------------------------------------
+
+set -euf
+[ "${MVNW_VERBOSE-}" != debug ] || set -x
+
+# OS specific support.
+native_path() { printf %s\\n "$1"; }
+case "$(uname)" in
+CYGWIN* | MINGW*)
+  [ -z "${JAVA_HOME-}" ] || JAVA_HOME="$(cygpath --unix "$JAVA_HOME")"
+  native_path() { cygpath --path --windows "$1"; }
+  ;;
+esac
+
+# set JAVACMD and JAVACCMD
+set_java_home() {
+  # For Cygwin and MinGW, ensure paths are in Unix format before anything is touched
+  if [ -n "${JAVA_HOME-}" ]; then
+    if [ -x "$JAVA_HOME/jre/sh/java" ]; then
+      # IBM's JDK on AIX uses strange locations for the executables
+      JAVACMD="$JAVA_HOME/jre/sh/java"
+      JAVACCMD="$JAVA_HOME/jre/sh/javac"
+    else
+      JAVACMD="$JAVA_HOME/bin/java"
+      JAVACCMD="$JAVA_HOME/bin/javac"
+
+      if [ ! -x "$JAVACMD" ] || [ ! -x "$JAVACCMD" ]; then
+        echo "The JAVA_HOME environment variable is not defined correctly, so mvnw cannot run." >&2
+        echo "JAVA_HOME is set to \"$JAVA_HOME\", but \"\$JAVA_HOME/bin/java\" or \"\$JAVA_HOME/bin/javac\" does not exist." >&2
+        return 1
+      fi
+    fi
+  else
+    JAVACMD="$(
+      'set' +e
+      'unset' -f command 2>/dev/null
+      'command' -v java
+    )" || :
+    JAVACCMD="$(
+      'set' +e
+      'unset' -f command 2>/dev/null
+      'command' -v javac
+    )" || :
+
+    if [ ! -x "${JAVACMD-}" ] || [ ! -x "${JAVACCMD-}" ]; then
+      echo "The java/javac command does not exist in PATH nor is JAVA_HOME set, so mvnw cannot run." >&2
+      return 1
+    fi
+  fi
+}
+
+# hash string like Java String::hashCode
+hash_string() {
+  str="${1:-}" h=0
+  while [ -n "$str" ]; do
+    char="${str%"${str#?}"}"
+    h=$(((h * 31 + $(LC_CTYPE=C printf %d "'$char")) % 4294967296))
+    str="${str#?}"
+  done
+  printf %x\\n $h
+}
+
+verbose() { :; }
+[ "${MVNW_VERBOSE-}" != true ] || verbose() { printf %s\\n "${1-}"; }
+
+die() {
+  printf %s\\n "$1" >&2
+  exit 1
+}
+
+trim() {
+  # MWRAPPER-139:
+  #   Trims trailing and leading whitespace, carriage returns, tabs, and linefeeds.
+  #   Needed for removing poorly interpreted newline sequences when running in more
+  #   exotic environments such as mingw bash on Windows.
+  printf "%s" "${1}" | tr -d '[:space:]'
+}
+
+# parse distributionUrl and optional distributionSha256Sum, requires .mvn/wrapper/maven-wrapper.properties
+while IFS="=" read -r key value; do
+  case "${key-}" in
+  distributionUrl) distributionUrl=$(trim "${value-}") ;;
+  distributionSha256Sum) distributionSha256Sum=$(trim "${value-}") ;;
+  esac
+done <"${0%/*}/.mvn/wrapper/maven-wrapper.properties"
+[ -n "${distributionUrl-}" ] || die "cannot read distributionUrl property in ${0%/*}/.mvn/wrapper/maven-wrapper.properties"
+
+case "${distributionUrl##*/}" in
+maven-mvnd-*bin.*)
+  MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/
+  case "${PROCESSOR_ARCHITECTURE-}${PROCESSOR_ARCHITEW6432-}:$(uname -a)" in
+  *AMD64:CYGWIN* | *AMD64:MINGW*) distributionPlatform=windows-amd64 ;;
+  :Darwin*x86_64) distributionPlatform=darwin-amd64 ;;
+  :Darwin*arm64) distributionPlatform=darwin-aarch64 ;;
+  :Linux*x86_64*) distributionPlatform=linux-amd64 ;;
+  *)
+    echo "Cannot detect native platform for mvnd on $(uname)-$(uname -m), use pure java version" >&2
+    distributionPlatform=linux-amd64
+    ;;
+  esac
+  distributionUrl="${distributionUrl%-bin.*}-$distributionPlatform.zip"
+  ;;
+maven-mvnd-*) MVN_CMD=mvnd.sh _MVNW_REPO_PATTERN=/maven/mvnd/ ;;
+*) MVN_CMD="mvn${0##*/mvnw}" _MVNW_REPO_PATTERN=/org/apache/maven/ ;;
+esac
+
+# apply MVNW_REPOURL and calculate MAVEN_HOME
+# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-<version>,maven-mvnd-<version>-<platform>}/<hash>
+[ -z "${MVNW_REPOURL-}" ] || distributionUrl="$MVNW_REPOURL$_MVNW_REPO_PATTERN${distributionUrl#*"$_MVNW_REPO_PATTERN"}"
+distributionUrlName="${distributionUrl##*/}"
+distributionUrlNameMain="${distributionUrlName%.*}"
+distributionUrlNameMain="${distributionUrlNameMain%-bin}"
+MAVEN_USER_HOME="${MAVEN_USER_HOME:-${HOME}/.m2}"
+MAVEN_HOME="${MAVEN_USER_HOME}/wrapper/dists/${distributionUrlNameMain-}/$(hash_string "$distributionUrl")"
+
+exec_maven() {
+  unset MVNW_VERBOSE MVNW_USERNAME MVNW_PASSWORD MVNW_REPOURL || :
+  exec "$MAVEN_HOME/bin/$MVN_CMD" "$@" || die "cannot exec $MAVEN_HOME/bin/$MVN_CMD"
+}
+
+if [ -d "$MAVEN_HOME" ]; then
+  verbose "found existing MAVEN_HOME at $MAVEN_HOME"
+  exec_maven "$@"
+fi
+
+case "${distributionUrl-}" in
+*?-bin.zip | *?maven-mvnd-?*-?*.zip) ;;
+*) die "distributionUrl is not valid, must match *-bin.zip or maven-mvnd-*.zip, but found '${distributionUrl-}'" ;;
+esac
+
+# prepare tmp dir
+if TMP_DOWNLOAD_DIR="$(mktemp -d)" && [ -d "$TMP_DOWNLOAD_DIR" ]; then
+  clean() { rm -rf -- "$TMP_DOWNLOAD_DIR"; }
+  trap clean HUP INT TERM EXIT
+else
+  die "cannot create temp dir"
+fi
+
+mkdir -p -- "${MAVEN_HOME%/*}"
+
+# Download and Install Apache Maven
+verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
+verbose "Downloading from: $distributionUrl"
+verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"
+
+# select .zip or .tar.gz
+if ! command -v unzip >/dev/null; then
+  distributionUrl="${distributionUrl%.zip}.tar.gz"
+  distributionUrlName="${distributionUrl##*/}"
+fi
+
+# verbose opt
+__MVNW_QUIET_WGET=--quiet __MVNW_QUIET_CURL=--silent __MVNW_QUIET_UNZIP=-q __MVNW_QUIET_TAR=''
+[ "${MVNW_VERBOSE-}" != true ] || __MVNW_QUIET_WGET='' __MVNW_QUIET_CURL='' __MVNW_QUIET_UNZIP='' __MVNW_QUIET_TAR=v
+
+# normalize http auth
+case "${MVNW_PASSWORD:+has-password}" in
+'') MVNW_USERNAME='' MVNW_PASSWORD='' ;;
+has-password) [ -n "${MVNW_USERNAME-}" ] || MVNW_USERNAME='' MVNW_PASSWORD='' ;;
+esac
+
+if [ -z "${MVNW_USERNAME-}" ] && command -v wget >/dev/null; then
+  verbose "Found wget ... using wget"
+  wget ${__MVNW_QUIET_WGET:+"$__MVNW_QUIET_WGET"} "$distributionUrl" -O "$TMP_DOWNLOAD_DIR/$distributionUrlName" || die "wget: Failed to fetch $distributionUrl"
+elif [ -z "${MVNW_USERNAME-}" ] && command -v curl >/dev/null; then
+  verbose "Found curl ... using curl"
+  curl ${__MVNW_QUIET_CURL:+"$__MVNW_QUIET_CURL"} -f -L -o "$TMP_DOWNLOAD_DIR/$distributionUrlName" "$distributionUrl" || die "curl: Failed to fetch $distributionUrl"
+elif set_java_home; then
+  verbose "Falling back to use Java to download"
+  javaSource="$TMP_DOWNLOAD_DIR/Downloader.java"
+  targetZip="$TMP_DOWNLOAD_DIR/$distributionUrlName"
+  cat >"$javaSource" <<-END
+    public class Downloader extends java.net.Authenticator
+    {
+      protected java.net.PasswordAuthentication getPasswordAuthentication()
+      {
+        return new java.net.PasswordAuthentication( System.getenv( "MVNW_USERNAME" ), System.getenv( "MVNW_PASSWORD" ).toCharArray() );
+      }
+      public static void main( String[] args ) throws Exception
+      {
+        setDefault( new Downloader() );
+        java.nio.file.Files.copy( java.net.URI.create( args[0] ).toURL().openStream(), java.nio.file.Paths.get( args[1] ).toAbsolutePath().normalize() );
+      }
+    }
+    END
+  # For Cygwin/MinGW, switch paths to Windows format before running javac and java
+  verbose " - Compiling Downloader.java ..."
+  "$(native_path "$JAVACCMD")" "$(native_path "$javaSource")" || die "Failed to compile Downloader.java"
+  verbose " - Running Downloader.java ..."
+  "$(native_path "$JAVACMD")" -cp "$(native_path "$TMP_DOWNLOAD_DIR")" Downloader "$distributionUrl" "$(native_path "$targetZip")"
+fi
+
+# If specified, validate the SHA-256 sum of the Maven distribution zip file
+if [ -n "${distributionSha256Sum-}" ]; then
+  distributionSha256Result=false
+  if [ "$MVN_CMD" = mvnd.sh ]; then
+    echo "Checksum validation is not supported for maven-mvnd." >&2
+    echo "Please disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
+    exit 1
+  elif command -v sha256sum >/dev/null; then
+    if echo "$distributionSha256Sum  $TMP_DOWNLOAD_DIR/$distributionUrlName" | sha256sum -c >/dev/null 2>&1; then
+      distributionSha256Result=true
+    fi
+  elif command -v shasum >/dev/null; then
+    if echo "$distributionSha256Sum  $TMP_DOWNLOAD_DIR/$distributionUrlName" | shasum -a 256 -c >/dev/null 2>&1; then
+      distributionSha256Result=true
+    fi
+  else
+    echo "Checksum validation was requested but neither 'sha256sum' or 'shasum' are available." >&2
+    echo "Please install either command, or disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties." >&2
+    exit 1
+  fi
+  if [ $distributionSha256Result = false ]; then
+    echo "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised." >&2
+    echo "If you updated your Maven version, you need to update the specified distributionSha256Sum property." >&2
+    exit 1
+  fi
+fi
+
+# unzip and move
+if command -v unzip >/dev/null; then
+  unzip ${__MVNW_QUIET_UNZIP:+"$__MVNW_QUIET_UNZIP"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -d "$TMP_DOWNLOAD_DIR" || die "failed to unzip"
+else
+  tar xzf${__MVNW_QUIET_TAR:+"$__MVNW_QUIET_TAR"} "$TMP_DOWNLOAD_DIR/$distributionUrlName" -C "$TMP_DOWNLOAD_DIR" || die "failed to untar"
+fi
+printf %s\\n "$distributionUrl" >"$TMP_DOWNLOAD_DIR/$distributionUrlNameMain/mvnw.url"
+mv -- "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain" "$MAVEN_HOME" || [ -d "$MAVEN_HOME" ] || die "fail to move MAVEN_HOME"
+
+clean || :
+exec_maven "$@"

mvnw.cmd

@@ -0,0 +1,149 @@
+<# : batch portion
+@REM ----------------------------------------------------------------------------
+@REM Licensed to the Apache Software Foundation (ASF) under one
+@REM or more contributor license agreements.  See the NOTICE file
+@REM distributed with this work for additional information
+@REM regarding copyright ownership.  The ASF licenses this file
+@REM to you under the Apache License, Version 2.0 (the
+@REM "License"); you may not use this file except in compliance
+@REM with the License.  You may obtain a copy of the License at
+@REM
+@REM    http://www.apache.org/licenses/LICENSE-2.0
+@REM
+@REM Unless required by applicable law or agreed to in writing,
+@REM software distributed under the License is distributed on an
+@REM "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+@REM KIND, either express or implied.  See the License for the
+@REM specific language governing permissions and limitations
+@REM under the License.
+@REM ----------------------------------------------------------------------------
+
+@REM ----------------------------------------------------------------------------
+@REM Apache Maven Wrapper startup batch script, version 3.3.2
+@REM
+@REM Optional ENV vars
+@REM   MVNW_REPOURL - repo url base for downloading maven distribution
+@REM   MVNW_USERNAME/MVNW_PASSWORD - user and password for downloading maven
+@REM   MVNW_VERBOSE - true: enable verbose log; others: silence the output
+@REM ----------------------------------------------------------------------------
+
+@IF "%__MVNW_ARG0_NAME__%"=="" (SET __MVNW_ARG0_NAME__=%~nx0)
+@SET __MVNW_CMD__=
+@SET __MVNW_ERROR__=
+@SET __MVNW_PSMODULEP_SAVE=%PSModulePath%
+@SET PSModulePath=
+@FOR /F "usebackq tokens=1* delims==" %%A IN (`powershell -noprofile "& {$scriptDir='%~dp0'; $script='%__MVNW_ARG0_NAME__%'; icm -ScriptBlock ([Scriptblock]::Create((Get-Content -Raw '%~f0'))) -NoNewScope}"`) DO @(
+  IF "%%A"=="MVN_CMD" (set __MVNW_CMD__=%%B) ELSE IF "%%B"=="" (echo %%A) ELSE (echo %%A=%%B)
+)
+@SET PSModulePath=%__MVNW_PSMODULEP_SAVE%
+@SET __MVNW_PSMODULEP_SAVE=
+@SET __MVNW_ARG0_NAME__=
+@SET MVNW_USERNAME=
+@SET MVNW_PASSWORD=
+@IF NOT "%__MVNW_CMD__%"=="" (%__MVNW_CMD__% %*)
+@echo Cannot start maven from wrapper >&2 && exit /b 1
+@GOTO :EOF
+: end batch / begin powershell #>
+
+$ErrorActionPreference = "Stop"
+if ($env:MVNW_VERBOSE -eq "true") {
+  $VerbosePreference = "Continue"
+}
+
+# calculate distributionUrl, requires .mvn/wrapper/maven-wrapper.properties
+$distributionUrl = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionUrl
+if (!$distributionUrl) {
+  Write-Error "cannot read distributionUrl property in $scriptDir/.mvn/wrapper/maven-wrapper.properties"
+}
+
+switch -wildcard -casesensitive ( $($distributionUrl -replace '^.*/','') ) {
+  "maven-mvnd-*" {
+    $USE_MVND = $true
+    $distributionUrl = $distributionUrl -replace '-bin\.[^.]*$',"-windows-amd64.zip"
+    $MVN_CMD = "mvnd.cmd"
+    break
+  }
+  default {
+    $USE_MVND = $false
+    $MVN_CMD = $script -replace '^mvnw','mvn'
+    break
+  }
+}
+
+# apply MVNW_REPOURL and calculate MAVEN_HOME
+# maven home pattern: ~/.m2/wrapper/dists/{apache-maven-<version>,maven-mvnd-<version>-<platform>}/<hash>
+if ($env:MVNW_REPOURL) {
+  $MVNW_REPO_PATTERN = if ($USE_MVND) { "/org/apache/maven/" } else { "/maven/mvnd/" }
+  $distributionUrl = "$env:MVNW_REPOURL$MVNW_REPO_PATTERN$($distributionUrl -replace '^.*'+$MVNW_REPO_PATTERN,'')"
+}
+$distributionUrlName = $distributionUrl -replace '^.*/',''
+$distributionUrlNameMain = $distributionUrlName -replace '\.[^.]*$','' -replace '-bin$',''
+$MAVEN_HOME_PARENT = "$HOME/.m2/wrapper/dists/$distributionUrlNameMain"
+if ($env:MAVEN_USER_HOME) {
+  $MAVEN_HOME_PARENT = "$env:MAVEN_USER_HOME/wrapper/dists/$distributionUrlNameMain"
+}
+$MAVEN_HOME_NAME = ([System.Security.Cryptography.MD5]::Create().ComputeHash([byte[]][char[]]$distributionUrl) | ForEach-Object {$_.ToString("x2")}) -join ''
+$MAVEN_HOME = "$MAVEN_HOME_PARENT/$MAVEN_HOME_NAME"
+
+if (Test-Path -Path "$MAVEN_HOME" -PathType Container) {
+  Write-Verbose "found existing MAVEN_HOME at $MAVEN_HOME"
+  Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"
+  exit $?
+}
+
+if (! $distributionUrlNameMain -or ($distributionUrlName -eq $distributionUrlNameMain)) {
+  Write-Error "distributionUrl is not valid, must end with *-bin.zip, but found $distributionUrl"
+}
+
+# prepare tmp dir
+$TMP_DOWNLOAD_DIR_HOLDER = New-TemporaryFile
+$TMP_DOWNLOAD_DIR = New-Item -Itemtype Directory -Path "$TMP_DOWNLOAD_DIR_HOLDER.dir"
+$TMP_DOWNLOAD_DIR_HOLDER.Delete() | Out-Null
+trap {
+  if ($TMP_DOWNLOAD_DIR.Exists) {
+    try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
+    catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
+  }
+}
+
+New-Item -Itemtype Directory -Path "$MAVEN_HOME_PARENT" -Force | Out-Null
+
+# Download and Install Apache Maven
+Write-Verbose "Couldn't find MAVEN_HOME, downloading and installing it ..."
+Write-Verbose "Downloading from: $distributionUrl"
+Write-Verbose "Downloading to: $TMP_DOWNLOAD_DIR/$distributionUrlName"
+
+$webclient = New-Object System.Net.WebClient
+if ($env:MVNW_USERNAME -and $env:MVNW_PASSWORD) {
+  $webclient.Credentials = New-Object System.Net.NetworkCredential($env:MVNW_USERNAME, $env:MVNW_PASSWORD)
+}
+[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
+$webclient.DownloadFile($distributionUrl, "$TMP_DOWNLOAD_DIR/$distributionUrlName") | Out-Null
+
+# If specified, validate the SHA-256 sum of the Maven distribution zip file
+$distributionSha256Sum = (Get-Content -Raw "$scriptDir/.mvn/wrapper/maven-wrapper.properties" | ConvertFrom-StringData).distributionSha256Sum
+if ($distributionSha256Sum) {
+  if ($USE_MVND) {
+    Write-Error "Checksum validation is not supported for maven-mvnd. `nPlease disable validation by removing 'distributionSha256Sum' from your maven-wrapper.properties."
+  }
+  Import-Module $PSHOME\Modules\Microsoft.PowerShell.Utility -Function Get-FileHash
+  if ((Get-FileHash "$TMP_DOWNLOAD_DIR/$distributionUrlName" -Algorithm SHA256).Hash.ToLower() -ne $distributionSha256Sum) {
+    Write-Error "Error: Failed to validate Maven distribution SHA-256, your Maven distribution might be compromised. If you updated your Maven version, you need to update the specified distributionSha256Sum property."
+  }
+}
+
+# unzip and move
+Expand-Archive "$TMP_DOWNLOAD_DIR/$distributionUrlName" -DestinationPath "$TMP_DOWNLOAD_DIR" | Out-Null
+Rename-Item -Path "$TMP_DOWNLOAD_DIR/$distributionUrlNameMain" -NewName $MAVEN_HOME_NAME | Out-Null
+try {
+  Move-Item -Path "$TMP_DOWNLOAD_DIR/$MAVEN_HOME_NAME" -Destination $MAVEN_HOME_PARENT | Out-Null
+} catch {
+  if (! (Test-Path -Path "$MAVEN_HOME" -PathType Container)) {
+    Write-Error "fail to move MAVEN_HOME"
+  }
+} finally {
+  try { Remove-Item $TMP_DOWNLOAD_DIR -Recurse -Force | Out-Null }
+  catch { Write-Warning "Cannot remove $TMP_DOWNLOAD_DIR" }
+}
+
+Write-Output "MVN_CMD=$MAVEN_HOME/bin/$MVN_CMD"

pom.xml

@@ -17,7 +17,7 @@
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter</artifactId>
-            <version>RELEASE</version>
+            <version>5.11.0</version>
             <scope>test</scope>
         </dependency>
     </dependencies>

src/main/java/com/ceticamarco/lambdatonic/Either.java

@@ -39,8 +39,8 @@ public sealed interface Either<L, R> permits Left, Right {
      *     <br /><br />
      *     This method
      *     applies a function(<i>fn</i>) to the values inside the data type,
-     *     returning a new data type(i.e., a new functor) if and only if the the Either
+     *     returning a new data type(i.e., a new functor) if and only if the Either
-     *     type is instantiated with the <i>Right</i> subtype. Otherwise it leaves the functor
+     *     type is instantiated to the <i>Right</i> subtype. Otherwise it leaves the functor
      *     unchanged.
      *     <br /><br />
      *     The type of the resulting functor is the return type specified on the <i>fn</i>