Fixed some methods that were implemented inefficiently or failed with StackOverflow.

orionll · orionll · commit 1d52ca309ffd · 2015-05-27T19:16:52.000+06:00
diff --git a/core/src/main/java/fj/data/LazyString.java b/core/src/main/java/fj/data/LazyString.java
@@ -1,13 +1,10 @@
 package fj.data;
 
-import fj.Equal;
-import fj.F;
-import fj.F2;
+import fj.*;
+
 import static fj.Function.compose;
 import static fj.Function.curry;
 import static fj.P.p;
-import fj.P1;
-import fj.P2;
 import static fj.data.Option.none;
 import static fj.data.Option.some;
 import static fj.data.Stream.join;
@@ -108,7 +105,9 @@ public CharSequence subSequence(final int start, final int end) {
    * @return The String representation of this lazy string.
    */
   public String toString() {
-    return new StringBuilder(length() + 16).append(this).toString();
+    final StringBuilder builder = new StringBuilder(length() + 16);
+    s.foreachDoEffect(c -> builder.append(c.charValue()));
+    return builder.toString();
   }
 
   /**
diff --git a/core/src/main/java/fj/data/List.java b/core/src/main/java/fj/data/List.java
@@ -159,8 +159,7 @@ public final <X> Either<X, A> toEither(final P1<X> x) {
    * @return A stream projection of this list.
    */
   public final Stream<A> toStream() {
-    final Stream<A> nil = Stream.nil();
-    return foldRight(a -> as -> as.cons(a), nil);
+    return isEmpty() ? Stream.nil() : Stream.cons(head(), P.lazy(() -> tail().toStream()));
   }
 
   /**
@@ -1569,7 +1568,11 @@ public static <A> List<A> replicate(final int n, final A a) {
    *         <code>to</code> value (exclusive).
    */
   public static List<Integer> range(final int from, final int to) {
-    return from >= to ? List.<Integer>nil() : cons(from, range(from + 1, to));
+    final Buffer<Integer> buf = Buffer.empty();
+    for (int i = from; i < to; i++) {
+      buf.snoc(i);
+    }
+    return buf.toList();
   }
 
   /**
diff --git a/core/src/main/java/fj/data/Stream.java b/core/src/main/java/fj/data/Stream.java
@@ -386,13 +386,7 @@ public final <B, C> F<B, Stream<C>> mapM(final F<A, F<B, C>> f) {
    * @return A new stream after performing the map, then final join.
    */
   public final <B> Stream<B> bind(final F<A, Stream<B>> f) {
-    return map(f).foldLeft((accumulator, element) -> {
-        Stream<B> result = accumulator;
-        for (B single : element) {
-            result = result.cons(single);
-        }
-        return result;
-    }, Stream.<B>nil()).reverse();
+    return foldRight(h -> (t -> f.f(h).append(t)), nil());
   }
 
   /**
@@ -1554,9 +1548,7 @@ public static <A> Stream<A> cons(final A head, final P1<Stream<A>> tail) {
    * @param o The stream of streams to join.
    * @return A new stream that is the join of the given streams.
    */
-  public static <A> Stream<A> join(final Stream<Stream<A>> o) {
-    return Monoid.<A>streamMonoid().sumRight(o);
-  }
+  public static <A> Stream<A> join(final Stream<Stream<A>> o) { return o.bind(identity()); }
 
   /**
    * A first-class version of join
diff --git a/core/src/test/java/fj/data/ListTest.java b/core/src/test/java/fj/data/ListTest.java
@@ -4,6 +4,7 @@
 
 import java.util.Arrays;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -39,4 +40,17 @@ public void integration() {
 
     }
 
+    @Test
+    public void convertToString() {
+        final int n = 10000;
+        final StringBuilder expected = new StringBuilder("List(");
+        for (int i = 0; i < n; i++) {
+            expected.append(i);
+            if (i < n - 1) {
+                expected.append(',');
+            }
+        }
+        expected.append(')');
+        assertEquals(expected.toString(), List.range(0, n).toString());
+    }
 }
diff --git a/core/src/test/java/fj/data/SeqTest.java b/core/src/test/java/fj/data/SeqTest.java
@@ -2,6 +2,7 @@
 
 import org.junit.Test;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
@@ -20,4 +21,17 @@ public void objectMethods() {
 
     }
 
+    @Test
+    public void convertToString() {
+        final int n = 10000;
+        final StringBuilder expected = new StringBuilder("Seq(");
+        for (int i = 0; i < n; i++) {
+            expected.append(i);
+            if (i < n - 1) {
+                expected.append(',');
+            }
+        }
+        expected.append(')');
+        assertEquals(expected.toString(), Seq.seq(Array.range(0, 10000).array()).toString());
+    }
 }
diff --git a/core/src/test/java/fj/data/StreamTest.java b/core/src/test/java/fj/data/StreamTest.java
@@ -0,0 +1,17 @@
+package fj.data;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Created by Zheka Kozlov on 27.05.2015.
+ */
+public class StreamTest {
+
+  @Test
+  public void infiniteStream() {
+    Stream<Integer> s = Stream.forever(Enumerator.intEnumerator, 0).bind(Stream::single);
+    assertEquals(List.range(0, 5), s.take(5).toList());
+  }
+}
