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Schema, for representing TSK schemas in HMaps
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‎CHANGELOG.md

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@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
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### Added
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- `Lens#toIso`, for converting a lens to an iso
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- `HMap#hMap` overloads up to 8 bindings deep
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- `Schema`, schemas for extracting multiple values from `HMap`s by aggregating `TypeSafeKey`s
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### Fixed
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- Deforested iterables execute in intended nesting order, where essential

‎src/main/java/com/jnape/palatable/lambda/adt/hmap/Schema.java

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package com.jnape.palatable.lambda.adt.hmap;
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import com.jnape.palatable.lambda.adt.Maybe;
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import com.jnape.palatable.lambda.adt.hlist.HList;
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import com.jnape.palatable.lambda.adt.hlist.HList.HCons;
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import com.jnape.palatable.lambda.adt.hlist.SingletonHList;
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import com.jnape.palatable.lambda.adt.hlist.Tuple2;
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import com.jnape.palatable.lambda.adt.hlist.Tuple3;
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import com.jnape.palatable.lambda.adt.hlist.Tuple4;
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import com.jnape.palatable.lambda.adt.hlist.Tuple5;
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import com.jnape.palatable.lambda.adt.hlist.Tuple6;
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import com.jnape.palatable.lambda.adt.hlist.Tuple7;
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import com.jnape.palatable.lambda.adt.hlist.Tuple8;
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import com.jnape.palatable.lambda.functions.builtin.fn2.Both;
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import com.jnape.palatable.lambda.lens.Lens;
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import static com.jnape.palatable.lambda.functions.builtin.fn2.Into.into;
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import static com.jnape.palatable.lambda.lens.lenses.HMapLens.valueAt;
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public interface Schema<Values extends HCons<?, ?>> extends Lens.Simple<HMap, Maybe<Values>> {
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@SuppressWarnings("unchecked")
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default <A, NewValues extends HCons<A, Values>> Schema<NewValues> add(TypeSafeKey<?, A> key) {
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return Lens.both(this, valueAt(key))
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.<Maybe<NewValues>>mapA(into((maybeValues, maybeA) -> maybeValues.zip(maybeA.fmap(a -> values -> (NewValues) values.cons(a)))))
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.<Maybe<NewValues>>mapB(Both.both(maybeNewValues -> maybeNewValues.fmap(HCons::tail),
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maybeNewValues -> maybeNewValues.fmap(HCons::head)))
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::apply;
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}
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static <A> Schema<SingletonHList<A>> schema(TypeSafeKey<?, A> key) {
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return valueAt(key)
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.mapA(ma -> ma.fmap(HList::singletonHList))
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.<Maybe<SingletonHList<A>>>mapB(maybeSingletonA -> maybeSingletonA.fmap(HCons::head))
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::apply;
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}
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static <A, B> Schema<Tuple2<A, B>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey) {
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return schema(bKey).add(aKey);
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}
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static <A, B, C> Schema<Tuple3<A, B, C>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey) {
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return schema(bKey, cKey).add(aKey);
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}
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static <A, B, C, D> Schema<Tuple4<A, B, C, D>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey,
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TypeSafeKey<?, D> dKey) {
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return schema(bKey, cKey, dKey).add(aKey);
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}
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static <A, B, C, D, E> Schema<Tuple5<A, B, C, D, E>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey,
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TypeSafeKey<?, D> dKey,
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TypeSafeKey<?, E> eKey) {
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return schema(bKey, cKey, dKey, eKey).add(aKey);
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}
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static <A, B, C, D, E, F> Schema<Tuple6<A, B, C, D, E, F>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey,
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TypeSafeKey<?, D> dKey,
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TypeSafeKey<?, E> eKey,
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TypeSafeKey<?, F> fKey) {
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return schema(bKey, cKey, dKey, eKey, fKey).add(aKey);
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}
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static <A, B, C, D, E, F, G> Schema<Tuple7<A, B, C, D, E, F, G>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey,
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TypeSafeKey<?, D> dKey,
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TypeSafeKey<?, E> eKey,
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TypeSafeKey<?, F> fKey,
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TypeSafeKey<?, G> gKey) {
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return schema(bKey, cKey, dKey, eKey, fKey, gKey).add(aKey);
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}
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static <A, B, C, D, E, F, G, H> Schema<Tuple8<A, B, C, D, E, F, G, H>> schema(TypeSafeKey<?, A> aKey,
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TypeSafeKey<?, B> bKey,
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TypeSafeKey<?, C> cKey,
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TypeSafeKey<?, D> dKey,
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TypeSafeKey<?, E> eKey,
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TypeSafeKey<?, F> fKey,
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TypeSafeKey<?, G> gKey,
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TypeSafeKey<?, H> hKey) {
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return schema(bKey, cKey, dKey, eKey, fKey, gKey, hKey).add(aKey);
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}
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}

‎src/test/java/com/jnape/palatable/lambda/adt/hmap/SchemaTest.java

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package com.jnape.palatable.lambda.adt.hmap;
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import org.junit.Test;
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import static com.jnape.palatable.lambda.adt.Maybe.just;
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import static com.jnape.palatable.lambda.adt.Maybe.nothing;
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import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
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import static com.jnape.palatable.lambda.adt.hmap.HMap.emptyHMap;
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import static com.jnape.palatable.lambda.adt.hmap.HMap.hMap;
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import static com.jnape.palatable.lambda.adt.hmap.Schema.schema;
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import static com.jnape.palatable.lambda.adt.hmap.TypeSafeKey.typeSafeKey;
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import static com.jnape.palatable.lambda.lens.functions.View.view;
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import static java.util.Arrays.asList;
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import static org.junit.Assert.assertEquals;
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import static testsupport.assertion.LensAssert.assertLensLawfulness;
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public class SchemaTest {
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@Test
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public void extractsValuesAtKeysFromMap() {
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TypeSafeKey.Simple<Byte> byteKey = typeSafeKey();
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TypeSafeKey.Simple<Short> shortKey = typeSafeKey();
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TypeSafeKey.Simple<Integer> intKey = typeSafeKey();
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TypeSafeKey.Simple<Long> longKey = typeSafeKey();
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TypeSafeKey.Simple<Float> floatKey = typeSafeKey();
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TypeSafeKey.Simple<Double> doubleKey = typeSafeKey();
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TypeSafeKey.Simple<Character> charKey = typeSafeKey();
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TypeSafeKey.Simple<Boolean> booleanKey = typeSafeKey();
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HMap m = hMap(byteKey, (byte) 1,
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shortKey, (short) 2,
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intKey, 3,
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longKey, 4L,
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floatKey, 5F,
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doubleKey, 6D,
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charKey, '7',
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booleanKey, true);
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assertLensLawfulness(schema(byteKey, shortKey, intKey, longKey, floatKey, doubleKey, charKey, booleanKey),
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asList(emptyHMap(),
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m),
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asList(nothing(),
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just(tuple((byte) 1, (short) 2, 3, 4L, 5F, 6D, '7', true))));
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}
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@Test
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public void extractsNothingIfAnyKeysMissing() {
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assertEquals(nothing(), view(schema(typeSafeKey()), emptyHMap()));
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}
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}

‎src/test/java/com/jnape/palatable/lambda/functions/recursion/TrampolineTest.java

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package com.jnape.palatable.lambda.functions.recursion;
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import com.jnape.palatable.lambda.adt.hlist.Tuple2;
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import com.jnape.palatable.lambda.functions.recursion.RecursiveResult;
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import org.junit.Test;
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import java.math.BigInteger;
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import java.util.function.Function;
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import static com.jnape.palatable.lambda.adt.hlist.HList.tuple;
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import static com.jnape.palatable.lambda.functions.builtin.fn2.Into.into;
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import static java.math.BigInteger.ONE;
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import static org.junit.Assert.assertEquals;
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import static com.jnape.palatable.lambda.functions.recursion.RecursiveResult.recurse;
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import static com.jnape.palatable.lambda.functions.recursion.RecursiveResult.terminate;
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import static com.jnape.palatable.lambda.functions.recursion.Trampoline.trampoline;
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import static java.math.BigInteger.ONE;
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import static org.junit.Assert.assertEquals;
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public class TrampolineTest {
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