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more examples
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‎src/main/java/com/jnape/palatable/lambda/monad/transformer/interpreter/Example.java

Lines changed: 35 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,7 @@
1010
import com.jnape.palatable.lambda.monad.MonadRec;
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import com.jnape.palatable.lambda.monad.transformer.builtin.*;
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import com.jnape.palatable.lambda.monad.transformer.interpreter.interpreters.Transformers;
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import com.jnape.palatable.lambda.monoid.Monoid;
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import static com.jnape.palatable.lambda.adt.Either.left;
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import static com.jnape.palatable.lambda.adt.Either.right;
@@ -24,6 +25,7 @@
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import static com.jnape.palatable.lambda.monad.transformer.interpreter.InterpreterH.lifting;
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import static com.jnape.palatable.lambda.monad.transformer.interpreter.interpreters.Transformers.*;
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import static com.jnape.palatable.lambda.monad.transformer.interpreter.interpreters.transformers.Construction.eitherT;
28+
import static com.jnape.palatable.lambda.monoid.Monoid.monoid;
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public class Example {
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public static void simpleCase() {
@@ -68,7 +70,7 @@ public static void deeplyNested() {
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Interpreter<EitherT<MaybeT<IdentityT<IO<?>, ?>, ?>, String, ?>, Integer, IO<?>, Integer> interpreter =
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Transformers.<MaybeT<IdentityT<IO<?>, ?>, ?>, String, Integer>interpretEitherT(recoveryFn)
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.andThen(interpretMaybeT(orElseGet))
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.andThenH(interpretIdentityT());
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.andThen(interpretIdentityT());
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interpreter
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.<IO<Integer>>interpret(eitherT(maybeT(identityT(io(() -> new Identity<>(just(right(42))))))))
@@ -85,11 +87,12 @@ public static void readerTCase() {
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// F a
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ReaderT<Boolean, EitherT<IO<?>, String, ?>, ?>, Integer,
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// G b
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IO<?>, Tuple2<Either<String, Integer>, Integer>
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IO<?>, Tuple2<Either<String, Integer>, Integer>
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> massiveInterpreter =
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Transformers.<Boolean, EitherT<IO<?>, String, ?>>runReaderT(true)
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Transformers
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.<Boolean, EitherT<IO<?>, String, ?>>runReaderT(true)
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.<IO<?>, Integer, Either<String, Integer>>andThen(runEitherT())
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.<StateT<Integer, IO<?>, ?>>andThenH(lifting(liftStateT()))
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.<StateT<Integer, IO<?>, ?>>andThen(lifting(liftStateT()))
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.andThen(eitherT())
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.andThen(runEitherT())
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.andThen(runStateT(10));
@@ -105,5 +108,33 @@ public static void main(String[] args) {
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nested();
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deeplyNested();
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readerTCase();
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iterateTCase();
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}
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public static <M extends MonadRec<?, M>, A> Interpreter<IterateT<M, ?>, A, M, A> folding(Monoid<A> monoid) {
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return new Interpreter<IterateT<M, ?>, A, M, A>() {
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@Override
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public <GB extends MonadRec<A, M>> GB interpret(MonadRec<A, IterateT<M, ?>> fa) {
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IterateT<M, A> ma = fa.coerce();
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MonadRec<Maybe<Tuple2<A, IterateT<M, A>>>, M> mmta = ma.runIterateT();
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return ma.fold((a, b) -> mmta.pure(monoid.apply(a, b)),
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mmta.pure(monoid.identity()));
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}
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};
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}
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public static <M extends MonadRec<?, M>, A> Interpreter<IterateT<M, ?>, A, M, Maybe<A>> head() {
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return new Interpreter<IterateT<M, ?>, A, M, Maybe<A>>() {
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@Override
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public <GB extends MonadRec<Maybe<A>, M>> GB interpret(MonadRec<A, IterateT<M, ?>> fa) {
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return fa.<IterateT<M, A>>coerce().runIterateT().fmap(m -> m.fmap(Tuple2::_1)).coerce();
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}
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};
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}
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private static void iterateTCase() {
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Interpreter<ReaderT<Boolean, IterateT<IO<?>, ?>, ?>, Integer, IO<?>, Integer> whoa =
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Example.<IO<?>, Integer>folding(monoid(Integer::sum, 0))
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.compose(runReaderT(true));
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}
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}

‎src/main/java/com/jnape/palatable/lambda/monad/transformer/interpreter/Interpreter.java

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -17,7 +17,7 @@ public <HC extends MonadRec<C, H>> HC interpret(MonadRec<A, F> fa) {
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};
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}
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default <H extends MonadRec<?, H>> Interpreter<F, A, H, B> andThenH(InterpreterH<G, H> gh) {
20+
default <H extends MonadRec<?, H>> Interpreter<F, A, H, B> andThen(InterpreterH<G, H> gh) {
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return new Interpreter<F, A, H, B>() {
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@Override
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public <GB extends MonadRec<B, H>> GB interpret(MonadRec<A, F> fa) {
@@ -30,7 +30,7 @@ default <E extends MonadRec<?, E>, Z> Interpreter<E, Z, G, B> compose(Interprete
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return efza.andThen(this);
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}
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33-
default <E extends MonadRec<?, E>> Interpreter<E, A, G, B> composeH(InterpreterH<E, F> ef) {
33+
default <E extends MonadRec<?, E>> Interpreter<E, A, G, B> compose(InterpreterH<E, F> ef) {
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return new Interpreter<E, A, G, B>() {
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@Override
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public <GB extends MonadRec<B, G>> GB interpret(MonadRec<A, E> ea) {

‎src/main/java/com/jnape/palatable/lambda/monad/transformer/interpreter/InterpreterH.java

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -20,15 +20,15 @@ public <A, HA extends MonadRec<A, H>> HA interpretH(MonadRec<A, F> fa) {
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}
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default <H extends MonadRec<?, H>, A, B> Interpreter<F, A, H, B> andThen(Interpreter<G, A, H, B> gh) {
23-
return gh.composeH(this);
23+
return gh.compose(this);
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}
2525

2626
default <E extends MonadRec<?, E>> InterpreterH<E, G> composeH(InterpreterH<E, F> ef) {
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return ef.andThenH(this);
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}
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3030
default <E extends MonadRec<?, E>, A, B> Interpreter<E, A, G, B> compose(Interpreter<E, A, F, B> gh) {
31-
return gh.andThenH(this);
31+
return gh.andThen(this);
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}
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3434
default <A> Interpreter<F, A, G, A> monomorphize() {

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