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Add traverse family of methods to Option #85

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Merged
mperry merged 1 commit into from
Jan 16, 2015
Merged

Add traverse family of methods to Option #85

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43 changes: 43 additions & 0 deletions core/src/main/java/fj/data/Option.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,8 @@
import fj.Unit;
import fj.Show;
import fj.function.Effect1;
import fj.Equal;
import fj.Ord;

import static fj.Function.*;
import static fj.P.p;
Expand Down Expand Up @@ -415,6 +417,47 @@ public final <B> Option<B> sequence(final Option<B> o) {
return bind(c);
}

public <L, B> Either<L, Option<B>> traverseEither(F<A, Either<L, B>> f) {
return map(a -> f.f(a).right().map(b -> some(b))).orSome(Either.right(none()));
}

public <B> IO<Option<B>> traverseIO(F<A, IO<B>> f) {
return map(a -> IOFunctions.map(f.f(a), b -> some(b))).orSome(IOFunctions.lazy(u -> none()));
}

public <B> List<Option<B>> traverseList(F<A, List<B>> f) {
return map(a -> f.f(a).map(b -> some(b))).orSome(List.list());
}

public <B> Option<Option<B>> traverseOption(F<A, Option<B>> f) {
return map(f);
}

public <B> Stream<Option<B>> traverseStream(F<A, Stream<B>> f) {
return map(a -> f.f(a).map(b -> some(b))).orSome(Stream.nil());
}

public <B> P1<Option<B>> traverseP1(F<A, P1<B>> f) {
return map(a -> f.f(a).map(b -> some(b))).orSome(P.p(none()));
}

public <B> Seq<Option<B>> traverseSeq(F<A, Seq<B>> f) {
return map(a -> f.f(a).map(b -> some(b))).orSome(Seq.empty());
}

public <B> Set<Option<B>> traverseSet(Ord<B> ord, F<A, Set<B>> f) {
Ord<Option<B>> optOrd = Ord.optionOrd(ord);
return map(a -> f.f(a).map(optOrd, b -> some(b))).orSome(Set.empty(optOrd));
}

public <B> F2<Ord<B>, F<A, Set<B>>, Set<Option<B>>> traverseSet() {
return (o, f) -> traverseSet(o, f);
}

public <E, B> Validation<E, Option<B>> traverseValidation(F<A, Validation<E, B>> f) {
return map(a -> f.f(a).map(b -> some(b))).orSome(Validation.success(none()));
}

/**
* Performs function application within an optional value (applicative functor pattern).
*
Expand Down
30 changes: 30 additions & 0 deletions core/src/test/java/fj/data/OptionTest.java
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
package fj.data;

import org.junit.Assert;
import org.junit.Test;

import static fj.data.Option.some;
import static org.junit.Assert.assertTrue;

/**
* Created by MarkPerry on 15/01/2015.
*/
public class OptionTest {

@Test
public void equals() {
int max = 4;
assertTrue(some(1).equals(some(1)));
assertTrue(some(List.range(1, max)).equals(some(List.range(1, max))));
}

@Test
public void traverseList() {
int max = 3;
List<Option<Integer>> actual = some(max).traverseList(a -> List.range(1, a + 1));
List<Option<Integer>> expected = List.range(1, max + 1).map(i -> some(i));
System.out.println(String.format("actual: %s, expected: %s", actual.toString(), expected.toString()));
assertTrue(actual.equals(expected));
}

}