Add snoc to HNil, SingletonHList, and Tuple classes

palatable · Jun 18, 2020 · 7ec5690 · 7ec5690
1 parent 66b0459
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 ### Added
 - `$`, function application represented as a higher-order `Fn2`
 - `Fn1#withSelf`, a static method for constructing a self-referencing `Fn1` 
+- `HNil/SingletonHList/TupleX#snoc`, a method to add a new last element (append to a tuple)
 
 ## [5.2.0] - 2020-02-12
 

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/HList.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/HList.java
@@ -297,5 +297,16 @@ private HNil() {
         public <Head> SingletonHList<Head> cons(Head head) {
             return new SingletonHList<>(head);
         }
+
+        /**
+         * Snoc an element onto the back of this HList.
+         *
+         * @param last   the new last element
+         * @param <Last> the new last element type
+         * @return the updated HList
+         */
+        public <Last> SingletonHList<Last> snoc(Last last) {
+            return new SingletonHList<>(last);
+        }
     }
 }
diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/SingletonHList.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/SingletonHList.java
@@ -39,6 +39,17 @@ public <_0> Tuple2<_0, _1> cons(_0 _0) {
         return new Tuple2<>(_0, this);
     }
 
+
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _2   the new last element
+     * @return the updated HList
+     */
+    public <_2> Tuple2<_1, _2> snoc(_2 _2) {
+        return tuple(head(), _2);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple2.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple2.java
@@ -75,6 +75,16 @@ public <_0> Tuple3<_0, _1, _2> cons(_0 _0) {
         return new Tuple3<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _3   the new last element
+     * @return the updated HList
+     */
+    public <_3> Tuple3<_1, _2, _3> snoc(_3 _3) {
+        return tuple(_1, _2, _3);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple3.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple3.java
@@ -56,6 +56,16 @@ public <_0> Tuple4<_0, _1, _2, _3> cons(_0 _0) {
         return new Tuple4<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _4   the new last element
+     * @return the updated HList
+     */
+    public <_4> Tuple4<_1, _2, _3, _4> snoc(_4 _4) {
+        return tuple(_1, _2, _3, _4);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple4.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple4.java
@@ -59,6 +59,16 @@ public <_0> Tuple5<_0, _1, _2, _3, _4> cons(_0 _0) {
         return new Tuple5<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _5   the new last element
+     * @return the updated HList
+     */
+    public <_5> Tuple5<_1, _2, _3, _4, _5> snoc(_5 _5) {
+        return tuple(_1, _2, _3, _4, _5);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple5.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple5.java
@@ -62,6 +62,16 @@ public <_0> Tuple6<_0, _1, _2, _3, _4, _5> cons(_0 _0) {
         return new Tuple6<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _6   the new last element
+     * @return the updated HList
+     */
+    public <_6> Tuple6<_1, _2, _3, _4, _5, _6> snoc(_6 _6) {
+        return tuple(_1, _2, _3, _4, _5, _6);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple6.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple6.java
@@ -66,6 +66,16 @@ public <_0> Tuple7<_0, _1, _2, _3, _4, _5, _6> cons(_0 _0) {
         return new Tuple7<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _7   the new last element
+     * @return the updated HList
+     */
+    public <_7> Tuple7<_1, _2, _3, _4, _5, _6, _7> snoc(_7 _7) {
+        return tuple(_1, _2, _3, _4, _5, _6, _7);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple7.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple7.java
@@ -70,6 +70,16 @@ public <_0> Tuple8<_0, _1, _2, _3, _4, _5, _6, _7> cons(_0 _0) {
         return new Tuple8<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _8   the new last element
+     * @return the updated HList
+     */
+    public <_8> Tuple8<_1, _2, _3, _4, _5, _6, _7, _8> snoc(_8 _8) {
+        return tuple(_1, _2, _3, _4, _5, _6, _7, _8);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple8.java b/src/main/java/com/jnape/palatable/lambda/adt/hlist/Tuple8.java
@@ -74,6 +74,16 @@ public <_0> HCons<_0, Tuple8<_1, _2, _3, _4, _5, _6, _7, _8>> cons(_0 _0) {
         return new HCons<>(_0, this);
     }
 
+    /**
+     * Snoc an element onto the back of this HList.
+     *
+     * @param _9   the new last element
+     * @return the updated HList
+     */
+    public <_9> HCons<_1, Tuple8<_2, _3, _4, _5, _6, _7, _8, _9>> snoc(_9 _9) {
+        return singletonHList(_9).cons(_8).cons(_7).cons(_6).cons(_5).cons(_4).cons(_3).cons(_2).cons(_1);
+    }
+
     /**
      * {@inheritDoc}
      */

diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/HListTest.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/HListTest.java
@@ -68,4 +68,10 @@ public void hashCodeUsesDecentDistribution() {
         assertNotEquals(nil().cons(1).hashCode(), nil().cons(2).hashCode());
         assertNotEquals(nil().cons(1).cons(2).hashCode(), nil().cons(1).cons(3).hashCode());
     }
+
+    @Test
+    public void snoc() {
+        SingletonHList<Float> tuple = nil().snoc((float) 4.0);
+        assertEquals(4.0, tuple.head(), 0.01);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/SingletonHListTest.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/SingletonHListTest.java
@@ -13,6 +13,7 @@
 
 import static com.jnape.palatable.lambda.adt.hlist.HList.nil;
 import static com.jnape.palatable.lambda.adt.hlist.HList.singletonHList;
+import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
 import static com.jnape.palatable.lambda.adt.hlist.SingletonHList.pureSingletonHList;
 import static org.junit.Assert.assertEquals;
 
@@ -56,4 +57,10 @@ public void staticPure() {
         SingletonHList<Integer> singletonHList = pureSingletonHList().apply(1);
         assertEquals(singletonHList(1), singletonHList);
     }
+
+    @Test
+    public void snoc() {
+        Tuple2<Byte, Character> tuple = singletonHList((byte) 127).snoc('x');
+        assertEquals(tuple((byte) 127, 'x'), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple2Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple2Test.java
@@ -143,4 +143,10 @@ public void staticPure() {
         Tuple2<Integer, String> tuple = pureTuple(1).apply("two");
         assertEquals(tuple(1, "two"), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple3<Long, Integer, String> tuple = tuple(Long.MAX_VALUE, 123).snoc("hi");
+        assertEquals(tuple(Long.MAX_VALUE, 123, "hi"), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple3Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple3Test.java
@@ -13,11 +13,14 @@
 import testsupport.traits.MonadRecLaws;
 import testsupport.traits.TraversableLaws;
 
+import java.time.Duration;
+
 import static com.jnape.palatable.lambda.adt.Maybe.just;
 import static com.jnape.palatable.lambda.adt.Maybe.nothing;
 import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
 import static com.jnape.palatable.lambda.adt.hlist.Tuple3.pureTuple;
 import static com.jnape.palatable.lambda.functions.builtin.fn1.Repeat.repeat;
+import static java.time.Duration.ofSeconds;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
 import static org.junit.Assert.assertEquals;
@@ -119,4 +122,10 @@ public void staticPure() {
         Tuple3<Integer, String, Character> tuple = pureTuple(1, "2").apply('3');
         assertEquals(tuple(1, "2", '3'), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple4<String, Long, Integer, Duration> tuple = tuple("qux", Long.MIN_VALUE, 7).snoc(ofSeconds(13));
+        assertEquals(tuple("qux", Long.MIN_VALUE, 7, ofSeconds(13)), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple4Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple4Test.java
@@ -122,4 +122,10 @@ public void staticPure() {
         Tuple4<Integer, String, Character, Boolean> tuple = pureTuple(1, "2", '3').apply(true);
         assertEquals(tuple(1, "2", '3', true), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple5<String, Integer, String, Long, Integer> tuple = tuple("qux", 7, "foo", 13L).snoc(17);
+        assertEquals(tuple("qux", 7, "foo", 13L, 17), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple5Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple5Test.java
@@ -128,4 +128,10 @@ public void staticPure() {
         Tuple5<Integer, String, Character, Boolean, Float> tuple = pureTuple(1, "2", '3', true).apply(5f);
         assertEquals(tuple(1, "2", '3', true, 5f), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple6<String, Integer, String, Integer, String, Integer> tuple = tuple("a", 5, "b", 7, "c").snoc(11);
+        assertEquals(tuple("a", 5, "b", 7, "c", 11), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple6Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple6Test.java
@@ -132,4 +132,10 @@ public void staticPure() {
         Tuple6<Integer, String, Character, Boolean, Float, Byte> tuple = pureTuple(1, "2", '3', true, 5f).apply((byte) 6);
         assertEquals(tuple(1, "2", '3', true, 5f, (byte) 6), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple7<Long, String, Integer, String, Integer, String, Integer> tuple = tuple(5L, "a", 7, "b", 11, "c").snoc(13);
+        assertEquals(tuple(5L, "a", 7, "b", 11, "c", 13), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple7Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple7Test.java
@@ -136,4 +136,10 @@ public void staticPure() {
                 pureTuple((byte) 1, (short) 2, 3, 4L, 5F, 6D).apply(true);
         assertEquals(tuple((byte) 1, (short) 2, 3, 4L, 5F, 6D, true), tuple);
     }
+
+    @Test
+    public void snoc() {
+        Tuple8<String, Long, String, Integer, String, Integer, String, Character> tuple = tuple("b", 7L, "c", 11, "d", 13, "e").snoc('f');
+        assertEquals(tuple("b", 7L, "c", 11, "d", 13, "e", 'f'), tuple);
+    }
 }
diff --git a/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple8Test.java b/src/test/java/com/jnape/palatable/lambda/adt/hlist/Tuple8Test.java
@@ -14,6 +14,8 @@
 import testsupport.traits.MonadRecLaws;
 import testsupport.traits.TraversableLaws;
 
+import java.time.LocalDate;
+
 import static com.jnape.palatable.lambda.adt.Maybe.just;
 import static com.jnape.palatable.lambda.adt.Maybe.nothing;
 import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
@@ -147,4 +149,11 @@ public void staticPure() {
                 pureTuple((byte) 1, (short) 2, 3, 4L, 5F, 6D, true).apply('8');
         assertEquals(tuple((byte) 1, (short) 2, 3, 4L, 5F, 6D, true, '8'), tuple);
     }
+
+    @Test
+    public void snoc() {
+        HCons<String, Tuple8<Long, String, Integer, String, Integer, String, Long, LocalDate>> actual = tuple("b", 7L, "c", 11, "d", 13, "e", 15L).snoc(LocalDate.of(2020, 4, 14));
+        assertEquals("b", actual.head());
+        assertEquals(actual.tail(), tuple(7L, "c", 11, "d", 13, "e", 15L, LocalDate.of(2020, 4, 14)));
+    }
 }