diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..6c0071a
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,13 @@
+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+
+sourceCompatibility = 1.5
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile group: 'junit', name: 'junit', version: '4.11'
+}
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
new file mode 100644
index 0000000..ca78035
Binary files /dev/null and b/gradle/wrapper/gradle-wrapper.jar differ
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..a6289bf
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Wed Oct 12 15:32:21 MSK 2016
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.13-bin.zip
diff --git a/gradlew b/gradlew
new file mode 100644
index 0000000..27309d9
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,164 @@
+#!/usr/bin/env bash
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Attempt to set APP_HOME
+# Resolve links: $0 may be a link
+PRG="$0"
+# Need this for relative symlinks.
+while [ -h "$PRG" ] ; do
+    ls=`ls -ld "$PRG"`
+    link=`expr "$ls" : '.*-> \(.*\)$'`
+    if expr "$link" : '/.*' > /dev/null; then
+        PRG="$link"
+    else
+        PRG=`dirname "$PRG"`"/$link"
+    fi
+done
+SAVED="`pwd`"
+cd "`dirname \"$PRG\"`/" >/dev/null
+APP_HOME="`pwd -P`"
+cd "$SAVED" >/dev/null
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+nonstop=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+  NONSTOP* )
+    nonstop=true
+    ;;
+esac
+
+CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar
+
+# Determine the Java command to use to start the JVM.
+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="$JAVA_HOME/jre/sh/java"
+    else
+        JAVACMD="$JAVA_HOME/bin/java"
+    fi
+    if [ ! -x "$JAVACMD" ] ; then
+        die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+    fi
+else
+    JAVACMD="java"
+    which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+
+Please set the JAVA_HOME variable in your environment to match the
+location of your Java installation."
+fi
+
+# Increase the maximum file descriptors if we can.
+if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then
+    MAX_FD_LIMIT=`ulimit -H -n`
+    if [ $? -eq 0 ] ; then
+        if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then
+            MAX_FD="$MAX_FD_LIMIT"
+        fi
+        ulimit -n $MAX_FD
+        if [ $? -ne 0 ] ; then
+            warn "Could not set maximum file descriptor limit: $MAX_FD"
+        fi
+    else
+        warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT"
+    fi
+fi
+
+# For Darwin, add options to specify how the application appears in the dock
+if $darwin; then
+    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
+fi
+
+# For Cygwin, switch paths to Windows format before running java
+if $cygwin ; then
+    APP_HOME=`cygpath --path --mixed "$APP_HOME"`
+    CLASSPATH=`cygpath --path --mixed "$CLASSPATH"`
+    JAVACMD=`cygpath --unix "$JAVACMD"`
+
+    # We build the pattern for arguments to be converted via cygpath
+    ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null`
+    SEP=""
+    for dir in $ROOTDIRSRAW ; do
+        ROOTDIRS="$ROOTDIRS$SEP$dir"
+        SEP="|"
+    done
+    OURCYGPATTERN="(^($ROOTDIRS))"
+    # Add a user-defined pattern to the cygpath arguments
+    if [ "$GRADLE_CYGPATTERN" != "" ] ; then
+        OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)"
+    fi
+    # Now convert the arguments - kludge to limit ourselves to /bin/sh
+    i=0
+    for arg in "$@" ; do
+        CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -`
+        CHECK2=`echo "$arg"|egrep -c "^-"`                                 ### Determine if an option
+
+        if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then                    ### Added a condition
+            eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"`
+        else
+            eval `echo args$i`="\"$arg\""
+        fi
+        i=$((i+1))
+    done
+    case $i in
+        (0) set -- ;;
+        (1) set -- "$args0" ;;
+        (2) set -- "$args0" "$args1" ;;
+        (3) set -- "$args0" "$args1" "$args2" ;;
+        (4) set -- "$args0" "$args1" "$args2" "$args3" ;;
+        (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;;
+        (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;;
+        (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;;
+        (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;;
+        (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;;
+    esac
+fi
+
+# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
+function splitJvmOpts() {
+    JVM_OPTS=("$@")
+}
+eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
+JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+
+exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..f6d5974
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,90 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windows variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+if "%@eval[2+2]" == "4" goto 4NT_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+goto execute
+
+:4NT_args
+@rem Get arguments from the 4NT Shell from JP Software
+set CMD_LINE_ARGS=%$
+
+:execute
+@rem Setup the command line
+
+set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar
+
+@rem Execute Gradle
+"%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS%
+
+:end
+@rem End local scope for the variables with windows NT shell
+if "%ERRORLEVEL%"=="0" goto mainEnd
+
+:fail
+rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of
+rem the _cmd.exe /c_ return code!
+if  not "" == "%GRADLE_EXIT_CONSOLE%" exit 1
+exit /b 1
+
+:mainEnd
+if "%OS%"=="Windows_NT" endlocal
+
+:omega
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..88a2644
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'FunctionalJava'
+
diff --git a/src/main/java/Collections.java b/src/main/java/Collections.java
new file mode 100644
index 0000000..4de4b51
--- /dev/null
+++ b/src/main/java/Collections.java
@@ -0,0 +1,68 @@
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+public class Collections {
+    public static <SourceType, DestType> List < DestType > map (Iterable<SourceType> iterable,
+                                                                Function1<? super SourceType, DestType> function) throws Exception {
+        List<DestType> resList = new LinkedList<DestType>();
+        for (SourceType curElement: iterable) {
+            resList.add(function.apply(curElement));
+        }
+        return resList;
+    }
+
+    public static <T> List<T> filter(Iterable<T> iterable,
+                                     Predicate<? super T> predicate) throws Exception{
+        List<T> trueList = new LinkedList<T>();
+        for (T curElement : iterable) {
+            if (predicate.apply(curElement)) {
+                trueList.add(curElement);
+            }
+        }
+        return trueList;
+    }
+
+    public static <T> List<T> takeWhile(Iterable<T> iterable,
+                                        Predicate<? super T> predicate) throws Exception {
+        List<T> resList = new LinkedList<T>();
+        Iterator<T> it = iterable.iterator();
+        while (it.hasNext()) {
+            T curElem = it.next();
+            if (!predicate.apply(curElem)) {
+                break;
+            }
+            resList.add(curElem);
+        }
+        return resList;
+    }
+
+    public static <T> List<T> takeUnless(Iterable<T> iterable, Predicate<? super T>
+            predicate) throws Exception {
+        return takeWhile(iterable, predicate.not());
+    }
+
+    public static <SourceType, DestType> DestType foldl(
+            Function2<? super DestType,? super SourceType,DestType> function,
+            DestType init, Iterable<SourceType> iterable) throws Exception {
+        DestType res = init;
+        for (SourceType elem : iterable) {
+            res = function.apply(res, elem);
+        }
+        return res;
+    }
+
+    public static <SourceType, DestType> DestType foldr(Function2<? super SourceType, ?super DestType, DestType> function,
+                                                        DestType init, Iterable<SourceType> iterable) throws Exception {
+        return foldrImpl(function, init, iterable.iterator());
+    }
+
+    private static <SourceType, DestType> DestType foldrImpl(Function2<? super SourceType, ? super DestType, DestType> function,
+                                                             DestType init, Iterator<SourceType> iterator) throws Exception {
+        if (iterator.hasNext()) {
+            SourceType curElem = iterator.next();
+            return function.apply(curElem, foldrImpl(function, init, iterator));
+        }
+        return init;
+    }
+}
diff --git a/src/main/java/Function1.java b/src/main/java/Function1.java
new file mode 100644
index 0000000..6ee796b
--- /dev/null
+++ b/src/main/java/Function1.java
@@ -0,0 +1,12 @@
+public abstract class Function1 < ArgType, ValueType > {
+    public abstract ValueType apply(ArgType x) throws Exception;
+
+    public < GValue > Function1 < ArgType, GValue > compose(final Function1 < ? super ValueType, GValue > g) {
+        return new Function1<ArgType, GValue>() {
+            @Override
+            public GValue apply(ArgType x) throws Exception{
+                return g.apply(Function1.this.apply(x));
+            }
+        };
+    }
+}
diff --git a/src/main/java/Function2.java b/src/main/java/Function2.java
new file mode 100644
index 0000000..07d4f9b
--- /dev/null
+++ b/src/main/java/Function2.java
@@ -0,0 +1,44 @@
+public abstract class Function2<ArgOneType, ArgTwoType, ValueType> {
+    public abstract ValueType apply(ArgOneType x, ArgTwoType y) throws Exception;
+
+    public < GValueType > Function2<ArgOneType, ArgTwoType, GValueType> compose(final Function1 < ? super ValueType, GValueType > g) {
+        return new Function2<ArgOneType, ArgTwoType, GValueType>() {
+            @Override
+            public GValueType apply(ArgOneType x, ArgTwoType y) throws Exception {
+                return g.apply(Function2.this.apply(x, y));
+            }
+        };
+    }
+
+    public Function1<ArgTwoType, ValueType> bind1(final ArgOneType argOne) {
+        return new Function1 < ArgTwoType, ValueType > () {
+            @Override
+            public ValueType apply(ArgTwoType x) throws Exception {
+                return Function2.this.apply(argOne, x);
+            }
+        };
+    }
+
+    public Function1<ArgOneType,ValueType> bind2(final ArgTwoType argTwo) {
+        return new Function1 < ArgOneType, ValueType > () {
+            @Override
+            public ValueType apply(ArgOneType x) throws Exception {
+                return Function2.this.apply(x, argTwo);
+            }
+        };
+    }
+
+    public Function1<ArgOneType,Function1<ArgTwoType, ValueType>> carry() {
+        return new Function1<ArgOneType, Function1<ArgTwoType, ValueType>> () {
+            @Override
+            public Function1<ArgTwoType, ValueType> apply(final ArgOneType x) {
+                return new Function1<ArgTwoType, ValueType> () {
+                    @Override
+                    public ValueType apply(ArgTwoType y) throws Exception{
+                        return Function2.this.apply(x, y);
+                    }
+                };
+            }
+        };
+    }
+}
\ No newline at end of file
diff --git a/src/main/java/Predicate.java b/src/main/java/Predicate.java
new file mode 100644
index 0000000..25d0c3f
--- /dev/null
+++ b/src/main/java/Predicate.java
@@ -0,0 +1,44 @@
+public abstract class Predicate <ArgType> extends Function1 <ArgType, Boolean> {
+    public abstract Boolean apply(ArgType x) throws Exception;
+
+    public Predicate<ArgType> or(final Predicate <? super ArgType> other) {
+        return new Predicate<ArgType>() {
+            @Override
+            public Boolean apply(ArgType x) throws Exception{
+                return Predicate.this.apply(x) || other.apply(x);
+            }
+        };
+    }
+
+    public Predicate<ArgType> and(final Predicate <? super ArgType> other) {
+        return new Predicate<ArgType>() {
+            @Override
+            public Boolean apply(ArgType x) throws Exception {
+                return Predicate.this.apply(x) && other.apply(x);
+            }
+        };
+    }
+
+    public Predicate<ArgType> not() {
+        return new Predicate<ArgType>() {
+            @Override
+            public Boolean apply(ArgType x) throws Exception {
+                return !Predicate.this.apply(x);
+            }
+        };
+    }
+
+    public static final Predicate<Object> ALWAYS_TRUE = new Predicate<Object>() {
+        @Override
+        public Boolean apply(Object x) {
+            return true;
+        }
+    };
+
+    public static final Predicate<Object> ALWAYS_FALSE = new Predicate<Object>() {
+        @Override
+        public Boolean apply(Object x) {
+            return false;
+        }
+    };
+}
diff --git a/src/test/java/CollectionsTest.java b/src/test/java/CollectionsTest.java
new file mode 100644
index 0000000..e4aded1
--- /dev/null
+++ b/src/test/java/CollectionsTest.java
@@ -0,0 +1,121 @@
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class CollectionsTest {
+    private ArrayList<Integer> numbers = new ArrayList<Integer>();
+    private final int TEST_LENGTH = 10;
+
+    @Before
+    public void initTests() {
+        for (int i = 0; i < TEST_LENGTH; i++) {
+            numbers.add(i);
+        }
+    }
+
+    @Test
+    public void filterTest() throws Exception {
+        List filtered = Collections.filter(numbers, new Predicate<Number>() {
+            @Override
+            public Boolean apply(Number x) {
+                return (Integer)x % 2 == 0;
+            }
+        });
+
+        for (int i = 0; i < TEST_LENGTH / 2; i++) {
+            Assert.assertEquals("Filter doesn't work correctly",
+                    i * 2, filtered.get(i));
+        }
+    }
+
+    @Test
+    public void foldlTest() throws Exception {
+        String allNumsFoldl = Collections.foldl(new Function2<String, Integer, String>() {
+            @Override
+            public String apply(String y, Integer x) {
+                return y.concat(x.toString());
+            }
+        }, "", numbers);
+
+        String allNums = "";
+        for (int i = 0; i < TEST_LENGTH; i++) {
+            allNums += String.valueOf(i);
+        }
+
+        Assert.assertEquals("Foldl doesn't work correctly.", allNums, allNumsFoldl);
+    }
+
+    @Test
+    public void foldrTest() throws Exception {
+        String allNumsFoldr = Collections.foldr(new Function2<Number, String, String>() {
+            @Override
+            public String apply(Number x, String y) {
+                return y.concat(x.toString());
+            }
+        }, "", numbers);
+
+        String allNums = "";
+        for (int i = TEST_LENGTH - 1; i >= 0; i--) {
+            allNums += String.valueOf(i);
+        }
+
+        Assert.assertEquals("Foldr doesn't work correctly.", allNums, allNumsFoldr);
+    }
+
+    @Test
+    public void mapTest() throws Exception {
+        List<Character> mapped = Collections.map(numbers, new Function1<Integer, Character>() {
+            @Override
+            public Character apply(Integer x) {
+                return (char)((int)'a' + (int)x);
+            }
+        });
+
+        Character[] answer = new Character[TEST_LENGTH];
+        int letter = (int)'a';
+        for (int i = 0; i < TEST_LENGTH; i++) {
+            answer[i] = (char)(i + (char)'a');
+        }
+        Assert.assertArrayEquals("Map doesn't work correctly.",
+                answer, mapped.toArray());
+    }
+
+    @Test
+    public void takeUnlessTest() throws Exception {
+        List<Integer> taken = Collections.takeUnless(numbers, new Predicate<Integer>() {
+            @Override
+            public Boolean apply(Integer x) {
+                return x >= TEST_LENGTH / 2;
+            }
+        });
+
+        Integer[] answer = new Integer[TEST_LENGTH / 2];
+        for (int i = 0; i < TEST_LENGTH / 2; i++) {
+            answer[i] = i;
+        }
+
+        Assert.assertArrayEquals("TakeUnless works incorrectly.",
+                answer, taken.toArray());
+    }
+
+    @Test
+    public void takeWhileTest() throws Exception {
+        List<Integer> taken = Collections.takeWhile(numbers, new Predicate<Number>() {
+            @Override
+            public Boolean apply(Number x) {
+                return (Integer)x < TEST_LENGTH / 2;
+            }
+        });
+
+        Integer[] answer = new Integer[TEST_LENGTH / 2];
+        for (int i = 0; i < TEST_LENGTH / 2; i++) {
+            answer[i] = i;
+        }
+
+        Assert.assertArrayEquals("TakeWhile works incorrectly.",
+                answer, taken.toArray());
+    }
+}
diff --git a/src/test/java/Function1Test.java b/src/test/java/Function1Test.java
new file mode 100644
index 0000000..627aa58
--- /dev/null
+++ b/src/test/java/Function1Test.java
@@ -0,0 +1,26 @@
+import org.junit.Assert;
+import org.junit.Test;
+
+public class Function1Test {
+    @Test
+    public void composeTest() throws Exception {
+        Function1<Number,Integer> square = new Function1<Number, Integer>() {
+            @Override
+            public Integer apply(Number x) {
+                return (Integer) x * (Integer)x;
+            }
+        };
+
+        Function1<Number,Integer> duplicate = new Function1<Number, Integer>() {
+            @Override
+            public Integer apply(Number x) {
+                return 2 * (Integer)x;
+            }
+        };
+
+        Assert.assertEquals("Compose works incorrectly.", (Integer) 18,
+                square.compose(duplicate).apply(3));
+        Assert.assertEquals("Compose works incorrectly.", (Integer)36,
+                duplicate.compose(square).apply(3));
+    }
+}
diff --git a/src/test/java/Function2Test.java b/src/test/java/Function2Test.java
new file mode 100644
index 0000000..db834e7
--- /dev/null
+++ b/src/test/java/Function2Test.java
@@ -0,0 +1,43 @@
+import org.junit.Assert;
+import org.junit.Test;
+
+public class Function2Test {
+    private Function2<Number, Number, Integer> difference = new Function2<Number, Number, Integer>() {
+        @Override
+        public Integer apply(Number x, Number y) {
+            return (Integer)x - (Integer)y;
+        }
+    };
+
+    private Function1<Number, Integer> triple = new Function1<Number, Integer>() {
+        @Override
+        public Integer apply(Number x) {
+            return 3 * (Integer) x;
+        }
+    };
+
+
+    @Test
+    public void composeTest() throws Exception {
+        Assert.assertEquals("Compose works incorrectly.", (Integer)6,
+                difference.<Integer>compose(triple).apply(10, 8));
+    }
+
+    @Test
+    public void bind1Test() throws Exception {
+        Assert.assertEquals("Binding first argument works incorrectly.",
+                (Integer)3, difference.<Integer>bind1(10).apply(7));
+    }
+
+    @Test
+    public void bind2Test() throws Exception {
+        Assert.assertEquals("Binding second argument doesn't work correctly.",
+                (Integer) 4, difference.<Integer>bind2(6).apply(10));
+    }
+
+    @Test
+    public void carryTest() throws Exception {
+        Assert.assertEquals("Carry works incorrectly.",
+                (Integer)5, difference.carry().apply(10).apply(5));
+    }
+}
diff --git a/src/test/java/PredicateTest.java b/src/test/java/PredicateTest.java
new file mode 100644
index 0000000..7b4f9f9
--- /dev/null
+++ b/src/test/java/PredicateTest.java
@@ -0,0 +1,68 @@
+import org.junit.Assert;
+import org.junit.Test;
+
+import static org.junit.Assert.fail;
+
+public class PredicateTest {
+    @Test
+    public void testConstants() throws Exception {
+        Assert.assertTrue("ALWAYS_TRUE should return true for any input.",
+                Predicate.ALWAYS_TRUE.apply(null));
+        Assert.assertFalse("ALWAYS_FALSE should return false for any input",
+                Predicate.ALWAYS_FALSE.apply(null));
+    }
+
+    @Test
+    public void testNot() throws Exception {
+        Assert.assertFalse("Not should invert the predicate value.",
+                Predicate.ALWAYS_TRUE.not().apply(null));
+        Assert.assertTrue("Not should invert the predicate value.",
+                Predicate.ALWAYS_FALSE.not().apply(null));
+    }
+
+    @Test
+    public void testAnd() throws Exception {
+        Assert.assertTrue("And should perform conjunction.",
+                Predicate.ALWAYS_TRUE.and(Predicate.ALWAYS_TRUE).apply(null));
+        Assert.assertFalse("And should perform conjunction.",
+                Predicate.ALWAYS_TRUE.and(Predicate.ALWAYS_FALSE).apply(null));
+        Assert.assertFalse("And should perform conjunction.",
+                Predicate.ALWAYS_FALSE.and(Predicate.ALWAYS_TRUE).apply(null));
+        Assert.assertFalse("And should perform conjunction.",
+                Predicate.ALWAYS_FALSE.and(Predicate.ALWAYS_FALSE).apply(null));
+
+        try {
+            Predicate.ALWAYS_FALSE.and(new Predicate<Object>() {
+                @Override
+                public Boolean apply(Object x) throws Exception {
+                    throw new Exception();
+                }
+        }).apply(new Object());
+        } catch (Exception e) {
+            fail("And should be lazy.");
+        }
+    }
+
+    @Test
+    public void testOr() throws Exception {
+        Assert.assertTrue("Or should perform disjunction.",
+                Predicate.ALWAYS_TRUE.or(Predicate.ALWAYS_TRUE).apply(null));
+        Assert.assertTrue("Or should perform disjunction.",
+                Predicate.ALWAYS_TRUE.or(Predicate.ALWAYS_FALSE).apply(null));
+        Assert.assertTrue("Or should perform disjunction.",
+                Predicate.ALWAYS_FALSE.or(Predicate.ALWAYS_TRUE).apply(null));
+        Assert.assertFalse("Or should perform disjunction.",
+                Predicate.ALWAYS_FALSE.or(Predicate.ALWAYS_FALSE).apply(null));
+
+        try {
+            Predicate.ALWAYS_TRUE.or(new Predicate<Object>() {
+                @Override
+                public Boolean apply(Object x) throws Exception {
+                    throw new Exception();
+                }
+            }).apply(null);
+        } catch (Exception e) {
+            fail("Or should be lazy.");
+        }
+    }
+}