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Commitd3a049c

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ReaderT#fmap and StateT#fmap don't unnecessarily rely on pure
1 parent3f23529 commitd3a049c

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5 files changed

+36
-3
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5 files changed

+36
-3
lines changed

‎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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###Changed
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-`IterateT#unfold` now only computes a single`Pure` for the given input
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-`ReaderT#fmap` and`StateT#fmap` avoid unnecessary calls to`pure`
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###Added
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-`$`, function application represented as a higher-order`Fn2`

‎src/main/java/com/jnape/palatable/lambda/monad/transformer/builtin/ReaderT.java‎

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@@ -120,7 +120,7 @@ public <B> ReaderT<R, M, B> pure(B b) {
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*/
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@Override
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public <B>ReaderT<R,M,B>fmap(Fn1<?superA, ?extendsB>fn) {
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returnMonadT.super.<B>fmap(fn).coerce();
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returnreaderT(r ->runReaderT(r).fmap(fn));
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}
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/**

‎src/main/java/com/jnape/palatable/lambda/monad/transformer/builtin/StateT.java‎

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@@ -144,7 +144,7 @@ public <B> StateT<S, M, B> pure(B b) {
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*/
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@Override
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public <B>StateT<S,M,B>fmap(Fn1<?superA, ?extendsB>fn) {
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returnMonadT.super.<B>fmap(fn).coerce();
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returnstateT(s ->runStateT(s).fmap(t ->t.biMapL(fn)));
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}
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/**
@@ -292,7 +292,7 @@ public static <S, M extends MonadRec<?, M>, A> StateT<S, M, A> stateT(
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publicstatic <S,MextendsMonadRec<?,M>>Pure<StateT<S,M, ?>>pureStateT(Pure<M>pureM) {
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returnnewPure<StateT<S,M, ?>>() {
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@Override
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public <A>StateT<S,M,A>checkedApply(Aa)throwsThrowable{
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public <A>StateT<S,M,A>checkedApply(Aa) {
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returnstateT(pureM.<A,MonadRec<A,M>>apply(a));
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}
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};

‎src/test/java/com/jnape/palatable/lambda/monad/transformer/builtin/ReaderTTest.java‎

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@@ -2,6 +2,7 @@
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importcom.jnape.palatable.lambda.adt.Maybe;
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importcom.jnape.palatable.lambda.adt.Unit;
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importcom.jnape.palatable.lambda.functions.Fn1;
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importcom.jnape.palatable.lambda.functor.builtin.Identity;
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importcom.jnape.palatable.lambda.io.IO;
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importcom.jnape.palatable.traitor.annotations.TestTraits;
@@ -12,6 +13,7 @@
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importjava.util.concurrent.CountDownLatch;
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importjava.util.concurrent.Executors;
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importjava.util.concurrent.atomic.AtomicInteger;
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importstaticcom.jnape.palatable.lambda.adt.Maybe.just;
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importstaticcom.jnape.palatable.lambda.adt.Unit.UNIT;
@@ -82,4 +84,17 @@ public void composedZip() {
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.unsafePerformAsyncIO(Executors.newFixedThreadPool(2))
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.join();
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}
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@Test
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publicvoidfmapInteractions() {
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AtomicIntegerinvocations =newAtomicInteger(0);
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ReaderT<Integer,Identity<?>,Integer>readerT =readerT(i -> {
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invocations.incrementAndGet();
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returnnewIdentity<>(i);
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});
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Fn1<Integer,Integer>plusOne =x ->x +1;
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readerT.fmap(plusOne).fmap(plusOne).fmap(plusOne).runReaderT(0);
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assertEquals(1,invocations.get());
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}
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}

‎src/test/java/com/jnape/palatable/lambda/monad/transformer/builtin/StateTTest.java‎

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@@ -16,15 +16,18 @@
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importjava.util.ArrayList;
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importjava.util.List;
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importjava.util.concurrent.atomic.AtomicInteger;
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importstaticcom.jnape.palatable.lambda.adt.Maybe.just;
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importstaticcom.jnape.palatable.lambda.adt.Unit.UNIT;
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importstaticcom.jnape.palatable.lambda.adt.hlist.HList.tuple;
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importstaticcom.jnape.palatable.lambda.functions.builtin.fn1.Id.id;
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importstaticcom.jnape.palatable.lambda.functor.builtin.Identity.pureIdentity;
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importstaticcom.jnape.palatable.lambda.optics.functions.Set.set;
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importstaticcom.jnape.palatable.lambda.optics.lenses.ListLens.elementAt;
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importstaticjava.util.Arrays.asList;
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importstaticorg.hamcrest.MatcherAssert.assertThat;
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importstaticorg.junit.Assert.assertEquals;
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importstatictestsupport.matchers.StateTMatcher.whenEvaluated;
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importstatictestsupport.matchers.StateTMatcher.whenExecuted;
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importstatictestsupport.matchers.StateTMatcher.whenRun;
@@ -119,4 +122,18 @@ public void staticLift() {
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assertThat(StateT.<String>liftStateT().apply(newIdentity<>(1)),
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whenRun("foo",newIdentity<>(tuple(1,"foo"))));
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}
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126+
@Test
127+
publicvoidfmapInteractions() {
128+
AtomicIntegerinvocations =newAtomicInteger(0);
129+
StateT.<Integer,Identity<?>,Integer>gets(x -> {
130+
invocations.incrementAndGet();
131+
returnnewIdentity<>(x);
132+
})
133+
.fmap(id())
134+
.fmap(id())
135+
.fmap(id())
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.<Identity<Tuple2<Integer,Integer>>>runStateT(0);
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assertEquals(1,invocations.get());
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}
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}

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