diff --git a/.gitignore b/.gitignore
index 32858aa..162f98c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,6 +3,10 @@
 # Mobile Tools for Java (J2ME)
 .mtj.tmp/
 
+*.iml
+build/*
+.idea/*
+
 # Package Files #
 *.jar
 *.war
diff --git a/build.gradle b/build.gradle
new file mode 100644
index 0000000..1c437fa
--- /dev/null
+++ b/build.gradle
@@ -0,0 +1,12 @@
+group 'org'
+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile group: 'junit', name: 'junit', version: '4.12'
+}
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
new file mode 100644
index 0000000..0c19db4
--- /dev/null
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -0,0 +1,6 @@
+#Sun Feb 14 15:03:16 MSK 2016
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.5-bin.zip
diff --git a/gradlew b/gradlew
new file mode 100755
index 0000000..91a7e26
--- /dev/null
+++ b/gradlew
@@ -0,0 +1,164 @@
+#!/usr/bin/env bash
+
+##############################################################################
+##
+##  Gradle start up script for UN*X
+##
+##############################################################################
+
+# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+DEFAULT_JVM_OPTS=""
+
+APP_NAME="Gradle"
+APP_BASE_NAME=`basename "$0"`
+
+# Use the maximum available, or set MAX_FD != -1 to use that value.
+MAX_FD="maximum"
+
+warn ( ) {
+    echo "$*"
+}
+
+die ( ) {
+    echo
+    echo "$*"
+    echo
+    exit 1
+}
+
+# OS specific support (must be 'true' or 'false').
+cygwin=false
+msys=false
+darwin=false
+case "`uname`" in
+  CYGWIN* )
+    cygwin=true
+    ;;
+  Darwin* )
+    darwin=true
+    ;;
+  MINGW* )
+    msys=true
+    ;;
+esac
+
+# For Cygwin, ensure paths are in UNIX format before anything is touched.
+if $cygwin ; then
+    [ -n "$JAVA_HOME" ] && JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
+fi
+
+# 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\"`/" >&-
+APP_HOME="`pwd -P`"
+cd "$SAVED" >&-
+
+CLASSPATH=$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" ] ; 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"`
+
+    # 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 "$@"
diff --git a/gradlew.bat b/gradlew.bat
new file mode 100644
index 0000000..aec9973
--- /dev/null
+++ b/gradlew.bat
@@ -0,0 +1,90 @@
+@if "%DEBUG%" == "" @echo off
+@rem ##########################################################################
+@rem
+@rem  Gradle startup script for Windows
+@rem
+@rem ##########################################################################
+
+@rem Set local scope for the variables with windows NT shell
+if "%OS%"=="Windows_NT" setlocal
+
+@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script.
+set DEFAULT_JVM_OPTS=
+
+set DIRNAME=%~dp0
+if "%DIRNAME%" == "" set DIRNAME=.
+set APP_BASE_NAME=%~n0
+set APP_HOME=%DIRNAME%
+
+@rem Find java.exe
+if defined JAVA_HOME goto findJavaFromJavaHome
+
+set JAVA_EXE=java.exe
+%JAVA_EXE% -version >NUL 2>&1
+if "%ERRORLEVEL%" == "0" goto init
+
+echo.
+echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH.
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:findJavaFromJavaHome
+set JAVA_HOME=%JAVA_HOME:"=%
+set JAVA_EXE=%JAVA_HOME%/bin/java.exe
+
+if exist "%JAVA_EXE%" goto init
+
+echo.
+echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME%
+echo.
+echo Please set the JAVA_HOME variable in your environment to match the
+echo location of your Java installation.
+
+goto fail
+
+:init
+@rem Get command-line arguments, handling Windowz variants
+
+if not "%OS%" == "Windows_NT" goto win9xME_args
+if "%@eval[2+2]" == "4" goto 4NT_args
+
+:win9xME_args
+@rem Slurp the command line arguments.
+set CMD_LINE_ARGS=
+set _SKIP=2
+
+:win9xME_args_slurp
+if "x%~1" == "x" goto execute
+
+set CMD_LINE_ARGS=%*
+goto execute
+
+:4NT_args
+@rem Get arguments from the 4NT Shell from JP Software
+set CMD_LINE_ARGS=%$
+
+: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..99a2019
--- /dev/null
+++ b/settings.gradle
@@ -0,0 +1,2 @@
+rootProject.name = 'task'
+
diff --git a/src/main/java/task/Collections.java b/src/main/java/task/Collections.java
new file mode 100644
index 0000000..154a45b
--- /dev/null
+++ b/src/main/java/task/Collections.java
@@ -0,0 +1,60 @@
+package task;
+
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+
+
+public class Collections {
+
+    public static <X, Y> List<Y> map(Function1<? super X, Y> f, Iterable<X> a) {
+        List<Y> list = new LinkedList<>();
+        for (X x : a) {
+            list.add(f.apply(x));
+        }
+        return list;
+    }
+
+    public static <X> List<X> filter(Predicate<? super X> p, Iterable<X> a) {
+        List<X> list = new LinkedList<>();
+        for (X x : a) {
+            if (p.apply(x)) {
+                list.add(x);
+            }
+        }
+        return list;
+    }
+
+    public static <X> List<X> takeWhile(Predicate<? super X> p, Iterable<X> a) {
+        List<X> list = new LinkedList<>();
+        for (X x : a) {
+            if (!p.apply(x)) break;
+            list.add(x);
+        }
+        return list;
+    }
+
+    public static <X> List<X> takeUnless(Predicate<? super X> p, Iterable<X> a) {
+        return takeWhile(p.not(), a);
+    }
+
+    public static <X, Y> Y foldr(Function2<? super Y, ? super X, Y> f, Y base, Iterable<X> a) {
+        return myFoldr(f, base, a.iterator());
+    }
+
+    public static <X, Y> Y foldl(Function2<? super Y, ? super X, Y> f, Y base, Iterable<X> a) {
+        for (X x : a) {
+            base = f.apply(base, x);
+        }
+        return base;
+    }
+
+    private static <X, Y> Y myFoldr(Function2<? super Y, ? super X, Y> f, Y base, Iterator<X> a) {
+        if (!a.hasNext()) {
+            return base;
+        } else {
+            X x = a.next();
+            return f.apply(myFoldr(f, base, a), x);
+        }
+    }
+}
diff --git a/src/main/java/task/Function1.java b/src/main/java/task/Function1.java
new file mode 100644
index 0000000..177a9a8
--- /dev/null
+++ b/src/main/java/task/Function1.java
@@ -0,0 +1,21 @@
+package task;
+
+
+public abstract class Function1<X, Y> {
+    public abstract Y apply(X x);
+
+    public <Z> Function1<X, Z> compose(Function1<? super Y, Z> other) {
+        Function1<X, Y> self = this;
+        return new Function1<X, Z>() {
+            private final Function1<X, Y> f = self;
+            private final Function1<? super Y, Z> g = other;
+
+            @Override
+            public Z apply(X x) {
+                return g.apply(f.apply(x));
+            }
+        };
+    }
+
+
+}
diff --git a/src/main/java/task/Function2.java b/src/main/java/task/Function2.java
new file mode 100644
index 0000000..bbf1ccc
--- /dev/null
+++ b/src/main/java/task/Function2.java
@@ -0,0 +1,54 @@
+package task;
+
+
+public abstract class Function2<X, Y, Z> {
+    public abstract Z apply(X x, Y y);
+
+    public <Z1> Function2<X, Y, Z1> compose(Function1<? super Z, Z1> other) {
+        Function2<X, Y, Z> self = this;
+        return new Function2<X, Y, Z1>() {
+            private Function1<? super Z, Z1> f = other;
+            private Function2<X, Y, Z> g = self;
+
+            @Override
+            public Z1 apply(X x, Y y) {
+                return f.apply(g.apply(x, y));
+            }
+        };
+    }
+
+    public Function1<Y, Z> bind1(X x) {
+        Function2<X, Y, Z> self = this;
+        return new Function1<Y, Z>() {
+            @Override
+            public Z apply(Y y) {
+                return self.apply(x, y);
+            }
+        };
+    }
+
+    public Function1<X, Z> bind2(Y y) {
+        Function2<X, Y, Z> self = this;
+        return new Function1<X, Z>() {
+            @Override
+            public Z apply(X x) {
+                return self.apply(x, y);
+            }
+        };
+    }
+
+    public Function1<X, Function1<Y, Z>> carry() {
+        Function2<X, Y, Z> self = this;
+        return new Function1<X, Function1<Y, Z>>() {
+            @Override
+            public Function1<Y, Z> apply(X x) {
+                return new Function1<Y, Z>() {
+                    @Override
+                    public Z apply(Y y) {
+                        return self.apply(x, y);
+                    }
+                };
+            }
+        };
+    }
+}
diff --git a/src/main/java/task/Predicate.java b/src/main/java/task/Predicate.java
new file mode 100644
index 0000000..8ebdf92
--- /dev/null
+++ b/src/main/java/task/Predicate.java
@@ -0,0 +1,50 @@
+package task;
+
+
+public abstract class Predicate<X> extends Function1<X, Boolean> {
+
+    public Predicate<X> or(Predicate<? super X> other) {
+        Predicate<X> self = this;
+        return new Predicate<X>() {
+            @Override
+            public Boolean apply(X x) {
+                return self.apply(x) || other.apply(x);
+            }
+        };
+    }
+
+    public Predicate<X> and(Predicate<? super X> other) {
+        Predicate<X> self = this;
+        return new Predicate<X>() {
+            @Override
+            public Boolean apply(X x) {
+                return self.apply(x) && other.apply(x);
+            }
+        };
+    }
+
+    public Predicate<X> not() {
+        Predicate<X> self = this;
+        return new Predicate<X>() {
+            @Override
+            public Boolean apply(X x) {
+                return !self.apply(x);
+            }
+        };
+    }
+
+    public final static Predicate<Object> ALWAYS_TRUE = new Predicate<Object>() {
+        @Override
+        public Boolean apply(Object o) {
+            return true;
+        }
+    };
+
+    public final static Predicate<Object> ALWAYS_FALSE = new Predicate<Object>() {
+        @Override
+        public Boolean apply(Object o) {
+            return false;
+        }
+    };
+
+}
diff --git a/src/test/java/task/CollectionsTest.java b/src/test/java/task/CollectionsTest.java
new file mode 100644
index 0000000..6e60cda
--- /dev/null
+++ b/src/test/java/task/CollectionsTest.java
@@ -0,0 +1,56 @@
+package task;
+
+import java.util.Arrays;
+
+import static org.junit.Assert.assertEquals;
+
+
+public class CollectionsTest {
+
+    public static final Integer[] ARRAY = {-2, -1, 0, 1, 2};
+    public static final Integer[] ARRAY_SQUARED = {4, 1, 0, 1, 4};
+    public static final Integer[] ARRAY_FILTERED = {0, 1, 2};
+    public static final Integer[] ARRAY_TAKEN_WHILE = {-2, -1, 0};
+    public static final Integer[] ARRAY_TAKEN_UNLESS = {-2, -1};
+    public static final Integer[] ARRAY_FOLD = {2, 3};
+    public static final Iterable<Integer> LIST = Arrays.asList(ARRAY);
+    public static final Iterable<Integer> LIST_SQUARED = Arrays.asList(ARRAY_SQUARED);
+    public static final Iterable<Integer> LIST_FILTERED = Arrays.asList(ARRAY_FILTERED);
+    public static final Iterable<Integer> LIST_TAKEN_WHILE = Arrays.asList(ARRAY_TAKEN_WHILE);
+    public static final Iterable<Integer> LIST_TAKEN_UNLESS = Arrays.asList(ARRAY_TAKEN_UNLESS);
+    public static final Iterable<Integer> LIST_FOLD = Arrays.asList(ARRAY_FOLD);
+
+    @org.junit.Test
+    public void testMap() throws Exception {
+        assertEquals(Collections.map(Function1Test.SQUARE, LIST), LIST_SQUARED);
+    }
+
+    @org.junit.Test
+    public void testFilter() throws Exception {
+        assertEquals(Collections.filter(PredicateTest.GE, LIST), LIST_FILTERED);
+    }
+
+    @org.junit.Test
+    public void testTakeWhile() throws Exception {
+        assertEquals(Collections.takeWhile(PredicateTest.LE, LIST), LIST_TAKEN_WHILE);
+    }
+
+    @org.junit.Test
+    public void testTakeUntil() throws Exception {
+        assertEquals(Collections.takeUnless(PredicateTest.GE, LIST), LIST_TAKEN_UNLESS);
+    }
+
+    @org.junit.Test
+    public void testTakeFoldr() throws Exception {
+        Number res = Collections.foldr(Function2Test.SND, 1, LIST_FOLD);
+        assertEquals(res, new Integer(2));
+    }
+
+    @org.junit.Test
+    public void testTakeFoldl() throws Exception {
+        Number res = Collections.foldl(Function2Test.SND, 1, LIST_FOLD);
+        assertEquals(res, new Integer(3));
+    }
+
+
+}
diff --git a/src/test/java/task/Function1Test.java b/src/test/java/task/Function1Test.java
new file mode 100644
index 0000000..417336c
--- /dev/null
+++ b/src/test/java/task/Function1Test.java
@@ -0,0 +1,39 @@
+package task;
+
+
+import static org.junit.Assert.*;
+
+
+public class Function1Test {
+
+    public static final Function1<Object, Integer> SUCC = new Function1<Object, Integer>() {
+        @Override
+        public Integer apply(Object x) {
+            return (Integer) x + 1;
+        }
+    };
+
+    public static final Function1<Object, Integer> SQUARE = new Function1<Object, Integer>() {
+        @Override
+        public Integer apply(Object x) {
+            return (Integer) x * (Integer) x;
+        }
+    };
+
+    @org.junit.Test
+    public void testApply() throws Exception {
+        assertEquals(SUCC.apply(1).intValue(), 2);
+        assertEquals(SQUARE.apply(2).intValue(), 4);
+    }
+
+    @org.junit.Test
+    public void testCompose() throws Exception {
+        Function1<Object, Integer> f = SUCC.compose(SQUARE);
+        Function1<Object, Integer> g = SQUARE.compose(SQUARE);
+        assertEquals(f.apply(1).intValue(), 4);
+        assertEquals(f.apply(2).intValue(), 9);
+        assertEquals(g.apply(2).intValue(), 16);
+    }
+
+
+}
diff --git a/src/test/java/task/Function2Test.java b/src/test/java/task/Function2Test.java
new file mode 100644
index 0000000..fd64bac
--- /dev/null
+++ b/src/test/java/task/Function2Test.java
@@ -0,0 +1,65 @@
+package task;
+
+
+import static org.junit.Assert.assertEquals;
+
+public class Function2Test {
+
+    public static final Function2<Object, Object, Integer> ADD = new Function2<Object, Object, Integer>() {
+        @Override
+        public Integer apply(Object x, Object y) {
+            return (Integer) x + (Integer) y;
+        }
+    };
+
+    public static final Function2<Object, Object, Integer> MUL = new Function2<Object, Object, Integer>() {
+        @Override
+        public Integer apply(Object x, Object y) {
+            return (Integer) x * (Integer) y;
+        }
+    };
+
+    public static final Function2<Object, Object, Integer> SND = new Function2<Object, Object, Integer>() {
+        @Override
+        public Integer apply(Object x, Object y) {
+            return (Integer) y;
+        }
+    };
+
+    public static final Function2<Object, Object, Integer> POW = new Function2<Object, Object, Integer>() {
+        @Override
+        public Integer apply(Object x, Object y) {
+            return (int) Math.round(Math.pow((Integer)x, (Integer)y));
+        }
+    };
+
+    @org.junit.Test
+    public void testApply() throws Exception {
+        assertEquals(ADD.apply(1, 3).intValue(), 4);
+        assertEquals(MUL.apply(2, 5).intValue(), 10);
+    }
+
+    @org.junit.Test
+    public void testCompose() throws Exception {
+        Function2<Object, Object, Integer> f = ADD.compose(Function1Test.SQUARE);
+        Function2<Object, Object, Integer> g = MUL.compose(Function1Test.SUCC);
+        assertEquals(f.apply(1, 2).intValue(), 9);
+        assertEquals(f.apply(2, 3).intValue(), 25);
+        assertEquals(g.apply(2, 4).intValue(), 9);
+    }
+
+    @org.junit.Test
+    public void testBind() throws Exception {
+        Function1<Object, Integer> f = POW.bind1(2);
+        Function1<Object, Integer> g = POW.bind2(2);
+        assertEquals(f.apply(3).intValue(), 8);
+        assertEquals(g.apply(3).intValue(), 9);
+    }
+
+    @org.junit.Test
+    public void testCarry() throws Exception {
+        Function1<Object, Function1<Object, Integer>> carried = POW.carry();
+        assertEquals(carried.apply(2).apply(3).intValue(), 8);
+        assertEquals(carried.apply(3).apply(2).intValue(), 9);
+    }
+}
diff --git a/src/test/java/task/PredicateTest.java b/src/test/java/task/PredicateTest.java
new file mode 100644
index 0000000..a7279a0
--- /dev/null
+++ b/src/test/java/task/PredicateTest.java
@@ -0,0 +1,74 @@
+package task;
+
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class PredicateTest {
+
+    public static final Predicate<Integer> GE = new Predicate<Integer>() {
+        @Override
+        public Boolean apply(Integer x) {
+            return x >= 0;
+        }
+    };
+
+    public static final Predicate<Integer> LE = new Predicate<Integer>() {
+        @Override
+        public Boolean apply(Integer x) {
+            return x <= 0;
+        }
+    };
+
+
+    @org.junit.Test
+    public void testApply() throws Exception {
+        assertTrue(GE.apply(1));
+        assertFalse(LE.apply(1));
+    }
+
+    @org.junit.Test
+    public void testOr() throws Exception {
+        Indicator indicator = new Indicator();
+        assertTrue(GE.or(indicator).apply(1));
+        assertFalse(indicator.wasApplied());
+        assertTrue(LE.or(GE).apply(0));
+    }
+
+    @org.junit.Test
+    public void testAnd() throws Exception {
+        assertTrue(GE.and(LE).apply(0));
+        Indicator indicator = new Indicator();
+        assertFalse(LE.and(indicator).apply(1));
+        assertFalse(indicator.wasApplied());
+    }
+
+    @org.junit.Test
+    public void testNot() throws Exception {
+        assertTrue(GE.not().apply(-1));
+        assertFalse(GE.not().apply(0));
+        assertFalse(GE.not().apply(1));
+    }
+
+    @org.junit.Test
+    public void testAlways() throws Exception {
+        assertTrue(Predicate.ALWAYS_TRUE.apply(1));
+        assertFalse(Predicate.ALWAYS_FALSE.apply(true));
+    }
+
+    private class Indicator extends Predicate<Object> {
+
+        private Boolean applied = false;
+
+        public Boolean wasApplied() {
+            return applied;
+        }
+
+        @Override
+        public Boolean apply(Object o) {
+            applied = true;
+            return true;
+        }
+    }
+
+}