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Sealing ReaderT
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-19
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  • src/main/java/com/jnape/palatable/lambda/monad/transformer/builtin

1 file changed

+27
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‎src/main/java/com/jnape/palatable/lambda/monad/transformer/builtin/ReaderT.java‎

Lines changed: 27 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -19,17 +19,25 @@
1919
* @param <M> the returned {@link Monad}
2020
* @param <A> the embedded output type
2121
*/
22-
public interface ReaderT<R, M extends Monad<?, M>, A> extends
22+
public final class ReaderT<R, M extends Monad<?, M>, A> implements
2323
MonadT<Fn1<R, ?>, M, A, ReaderT<R, M, ?>>,
2424
Cartesian<R, A, ReaderT<?, M, ?>> {
2525

26+
private final Fn1<? super R, ? extends Monad<A, M>> fn;
27+
28+
private ReaderT(Fn1<? super R, ? extends Monad<A, M>> fn) {
29+
this.fn = fn;
30+
}
31+
2632
/**
2733
* Run the computation represented by this {@link ReaderT}.
2834
*
2935
* @param r the input
3036
* @return the {¬@link Monad monadic} embedding {@link Monad}&lt;A, M&gt;
3137
*/
32-
Monad<A, M> runReaderT(R r);
38+
public <MA extends Monad<A, M>> MA runReaderT(R r) {
39+
return fn.apply(r).coerce();
40+
}
3341

3442
/**
3543
* Map the current {@link Monad monadic} embedding to a new one in a potentially different {@link Monad}.
@@ -40,7 +48,7 @@ public interface ReaderT<R, M extends Monad<?, M>, A> extends
4048
* @param <B> the new embedded result
4149
* @return the mapped {@link ReaderT}
4250
*/
43-
default <MA extends Monad<A, M>, N extends Monad<?, N>, B> ReaderT<R, N, B> mapReaderT(
51+
public <MA extends Monad<A, M>, N extends Monad<?, N>, B> ReaderT<R, N, B> mapReaderT(
4452
Fn1<? super MA, ? extends Monad<B, N>> fn) {
4553
return readerT(r -> fn.apply(runReaderT(r).coerce()));
4654
}
@@ -49,47 +57,47 @@ default <MA extends Monad<A, M>, N extends Monad<?, N>, B> ReaderT<R, N, B> mapR
4957
* {@inheritDoc}
5058
*/
5159
@Override
52-
default <GA extends Monad<A, M>, FGA extends Monad<GA, Fn1<R, ?>>> FGA run() {
60+
public <GA extends Monad<A, M>, FGA extends Monad<GA, Fn1<R, ?>>> FGA run() {
5361
return Fn1.<R, GA>fn1(r -> runReaderT(r).coerce()).coerce();
5462
}
5563

5664
/**
5765
* {@inheritDoc}
5866
*/
5967
@Override
60-
default <B> ReaderT<R, M, B> flatMap(Fn1<? super A, ? extends Monad<B, ReaderT<R, M, ?>>> f) {
68+
public <B> ReaderT<R, M, B> flatMap(Fn1<? super A, ? extends Monad<B, ReaderT<R, M, ?>>> f) {
6169
return readerT(r -> runReaderT(r).flatMap(a -> f.apply(a).<ReaderT<R, M, B>>coerce().runReaderT(r)));
6270
}
6371

6472
/**
6573
* {@inheritDoc}
6674
*/
6775
@Override
68-
default <B> ReaderT<R, M, B> pure(B b) {
76+
public <B> ReaderT<R, M, B> pure(B b) {
6977
return readerT(r -> runReaderT(r).pure(b));
7078
}
7179

7280
/**
7381
* {@inheritDoc}
7482
*/
7583
@Override
76-
default <B> ReaderT<R, M, B> fmap(Fn1<? super A, ? extends B> fn) {
84+
public <B> ReaderT<R, M, B> fmap(Fn1<? super A, ? extends B> fn) {
7785
return MonadT.super.<B>fmap(fn).coerce();
7886
}
7987

8088
/**
8189
* {@inheritDoc}
8290
*/
8391
@Override
84-
default <B> ReaderT<R, M, B> zip(Applicative<Fn1<? super A, ? extends B>, ReaderT<R, M, ?>> appFn) {
92+
public <B> ReaderT<R, M, B> zip(Applicative<Fn1<? super A, ? extends B>, ReaderT<R, M, ?>> appFn) {
8593
return readerT(r -> runReaderT(r).zip(appFn.<ReaderT<R, M, Fn1<? super A, ? extends B>>>coerce().runReaderT(r)));
8694
}
8795

8896
/**
8997
* {@inheritDoc}
9098
*/
9199
@Override
92-
default <B> Lazy<? extends ReaderT<R, M, B>> lazyZip(
100+
public <B> Lazy<ReaderT<R, M, B>> lazyZip(
93101
Lazy<? extends Applicative<Fn1<? super A, ? extends B>, ReaderT<R, M, ?>>> lazyAppFn) {
94102
return lazyAppFn.fmap(this::zip);
95103
}
@@ -98,63 +106,63 @@ default <B> Lazy<? extends ReaderT<R, M, B>> lazyZip(
98106
* {@inheritDoc}
99107
*/
100108
@Override
101-
default <B> ReaderT<R, M, B> discardL(Applicative<B, ReaderT<R, M, ?>> appB) {
109+
public <B> ReaderT<R, M, B> discardL(Applicative<B, ReaderT<R, M, ?>> appB) {
102110
return MonadT.super.discardL(appB).coerce();
103111
}
104112

105113
/**
106114
* {@inheritDoc}
107115
*/
108116
@Override
109-
default <B> ReaderT<R, M, A> discardR(Applicative<B, ReaderT<R, M, ?>> appB) {
117+
public <B> ReaderT<R, M, A> discardR(Applicative<B, ReaderT<R, M, ?>> appB) {
110118
return MonadT.super.discardR(appB).coerce();
111119
}
112120

113121
/**
114122
* {@inheritDoc}
115123
*/
116124
@Override
117-
default <Q, B> ReaderT<Q, M, B> diMap(Fn1<? super Q, ? extends R> lFn, Fn1<? super A, ? extends B> rFn) {
125+
public <Q, B> ReaderT<Q, M, B> diMap(Fn1<? super Q, ? extends R> lFn, Fn1<? super A, ? extends B> rFn) {
118126
return readerT(q -> runReaderT(lFn.apply(q)).fmap(rFn));
119127
}
120128

121129
/**
122130
* {@inheritDoc}
123131
*/
124132
@Override
125-
default <Q> ReaderT<Q, M, A> diMapL(Fn1<? super Q, ? extends R> fn) {
133+
public <Q> ReaderT<Q, M, A> diMapL(Fn1<? super Q, ? extends R> fn) {
126134
return (ReaderT<Q, M, A>) Cartesian.super.<Q>diMapL(fn);
127135
}
128136

129137
/**
130138
* {@inheritDoc}
131139
*/
132140
@Override
133-
default <B> ReaderT<R, M, B> diMapR(Fn1<? super A, ? extends B> fn) {
141+
public <B> ReaderT<R, M, B> diMapR(Fn1<? super A, ? extends B> fn) {
134142
return (ReaderT<R, M, B>) Cartesian.super.<B>diMapR(fn);
135143
}
136144

137145
/**
138146
* {@inheritDoc}
139147
*/
140148
@Override
141-
default <Q> ReaderT<Q, M, A> contraMap(Fn1<? super Q, ? extends R> fn) {
149+
public <Q> ReaderT<Q, M, A> contraMap(Fn1<? super Q, ? extends R> fn) {
142150
return (ReaderT<Q, M, A>) Cartesian.super.<Q>contraMap(fn);
143151
}
144152

145153
/**
146154
* {@inheritDoc}
147155
*/
148156
@Override
149-
default <C> ReaderT<Tuple2<C, R>, M, Tuple2<C, A>> cartesian() {
157+
public <C> ReaderT<Tuple2<C, R>, M, Tuple2<C, A>> cartesian() {
150158
return readerT(into((c, r) -> runReaderT(r).fmap(tupler(c))));
151159
}
152160

153161
/**
154162
* {@inheritDoc}
155163
*/
156164
@Override
157-
default ReaderT<R, M, Tuple2<R, A>> carry() {
165+
public ReaderT<R, M, Tuple2<R, A>> carry() {
158166
return (ReaderT<R, M, Tuple2<R, A>>) Cartesian.super.carry();
159167
}
160168

@@ -167,7 +175,7 @@ default ReaderT<R, M, Tuple2<R, A>> carry() {
167175
* @param <A> the embedded output type
168176
* @return the {@link ReaderT}
169177
*/
170-
static <R, M extends Monad<?, M>, A> ReaderT<R, M, A> readerT(Fn1<? super R, ? extends Monad<A, M>> fn) {
171-
return fn::apply;
178+
public static <R, M extends Monad<?, M>, A> ReaderT<R, M, A> readerT(Fn1<? super R, ? extends Monad<A, M>> fn) {
179+
return new ReaderT<>(fn);
172180
}
173181
}

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