本文整理了Java中fj.data.List.foldLeft()方法的一些代码示例，展示了List.foldLeft()的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。List.foldLeft()方法的具体详情如下：
包路径：fj.data.List
类名称：List
方法名：foldLeft

List.foldLeft介绍

[英]Provides a first-class version of foldLeft.
[中]提供foldLeft的一流版本。

代码示例

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Returns the product of a list of doubles.
 *
 * @param doubles A list of doubles to multiply together.
 * @return The product of the doubles in the list.
 */
public static double product(final List<Double> doubles) {
 return doubles.foldLeft((x, y) -> x * y, 1.0);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * If list contains a failure, returns a failure of the reduction of
 * all the failures using the semigroup, otherwise returns the successful list.
 */
public static <E, A> Validation<E, List<A>> sequence(final Semigroup<E> s, final List<Validation<E, A>> list) {
 if (list.exists(Validation::isFail)) {
  return Validation.fail(list.filter(Validation::isFail).map(v -> v.fail()).foldLeft1((F2<E, E, E>) s::sum));
 } else {
  return success(list.foldLeft((List<A> acc, Validation<E, A> v) -> acc.cons(v.success()), List.nil()).reverse());
 }
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Sums a list of doubles.
 *
 * @param doubles A list of doubles to sum.
 * @return The sum of the doubless in the list.
 */
public static double sum(final List<Double> doubles) {
 return doubles.foldLeft((x, y) -> x + y, 0.0);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * The length of this list.
 *
 * @return The length of this list.
 */
public final int length() {
 return foldLeft((i, a) -> i + 1, 0);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Performs a left-fold reduction across this list. This function runs in constant space.
 *
 * @param f The function to apply on each element of the list.
 * @param b The beginning value to start the application from.
 * @return The final result after the left-fold reduction.
 */
public final <B> B foldLeft(final F<B, F<A, B>> f, final B b) {
 return foldLeft(uncurryF2(f), b);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Provides a first-class version of foldLeft.
 *
 * @return The left fold function for lists.
 */
public static <A, B> F<F<B, F<A, B>>, F<B, F<List<A>, B>>> foldLeft() {
 return curry((f, b, as) -> as.foldLeft(f, b));
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Sums the given values with left-fold.
 *
 * @param as The values to sum.
 * @return The sum of the given values.
 */
public A sumLeft(final List<A> as) {
 return as.foldLeft(def::append, def.empty());
}

代码示例来源：origin: no.arktekk.unix/unix-sysv-pkg

public String toString()
{
  String eol = System.getProperty( "line.separator" );
  return toList().foldLeft( joiner.f( eol ), "" ).trim() + eol;
}

代码示例来源：origin: com.stratio.mojo.unix/unix-sysv-pkg

public String toString()
{
  return toList().foldLeft( joiner.f( EOL ), "" ).trim() + EOL;
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Performs a right-fold reduction across this list. This function uses O(length) stack space.
 *
 * @param f The function to apply on each element of the list.
 * @param b The beginning value to start the application from.
 * @return The final result after the right-fold reduction.
 */
public final <B> B foldRight(final F2<A, B, B> f, final B b) {
 return reverse().foldLeft(flip(f), b);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Reverse this list in constant stack space.
 *
 * @return A new list that is the reverse of this one.
 */
public final List<A> reverse() {
 return foldLeft((as, a) -> cons(a, as), nil());
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Adds nodes using the list of products with priority k and value a.  This operation takes O(list.length()).
 */
public PriorityQueue<K, A> enqueue(List<P2<K, A>> list) {
  return list.foldLeft((pq, p) -> pq.enqueue(p._1(), p._2()), this);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Adds the product of key-value (k, v) pairs to the trie.
 */
public HashArrayMappedTrie<K, V> set(final List<P2<K, V>> list) {
  return list.foldLeft(h -> p -> h.set(p._1(), p._2()), this);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Takes the first 2 elements of the list and applies the function to them,
 * then applies the function to the result and the third element and so on.
 *
 * @param f The function to apply on each element of the list.
 * @return The final result after the left-fold reduction.
 */
public final A foldLeft1(final F2<A, A, A> f) {
 if (isEmpty())
  throw error("Undefined: foldLeft1 on empty list");
 return tail().foldLeft(f, head());
}

代码示例来源：origin: it.unibz.inf.ontop/ontop-model

/**
 * Folds a list of boolean atoms into one AND(AND(...)) boolean atom.
 */
public static Expression foldBooleanConditions(List<Function> booleanAtoms) {
  if (booleanAtoms.length() == 0)
    return TRUE_EQ;
  Expression firstBooleanAtom = convertOrCastIntoBooleanAtom( booleanAtoms.head());
  return booleanAtoms.tail().foldLeft(new F2<Expression, Function, Expression>() {
    @Override
    public Expression f(Expression previousAtom, Function currentAtom) {
      return TERM_FACTORY.getFunctionAND(previousAtom, currentAtom);
    }
  }, firstBooleanAtom);
}

代码示例来源：origin: ontop/ontop

/**
 * Folds a list of boolean atoms into one AND(AND(...)) boolean atom.
 */
public Expression foldBooleanConditions(List<Function> booleanAtoms) {
  if (booleanAtoms.length() == 0)
    return TRUE_EQ;
  Expression firstBooleanAtom = convertOrCastIntoBooleanAtom( booleanAtoms.head());
  return booleanAtoms.tail().foldLeft(new F2<Expression, Function, Expression>() {
    @Override
    public Expression f(Expression previousAtom, Function currentAtom) {
      return termFactory.getFunctionAND(previousAtom, currentAtom);
    }
  }, firstBooleanAtom);
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Evaluate each action in the sequence from left to right, and collect the results.
 */
public static <S, A> State<S, List<A>> sequence(List<State<S, A>> list) {
 return list
   .foldLeft(
     (acc, ts) -> acc.flatMap(as -> ts.map(a -> cons(a, as))),
     State.<S, List<A>>constant(List.nil()))
   .map(as -> as.reverse());
}

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * If the list contains a failure, returns a Validation of the list of
 * fails in the list, otherwise returns a successful Validation with
 * the list of successful values.  Does not accumulate the failures into a
 * single failure using a semigroup.
 */
 public static <A, E> Validation<List<E>, List<A>> sequenceNonCumulative(List<Validation<E, A>> list) {
  if (list.exists(Validation::isFail)) {
   F2<List<E>, Validation<E, A>, List<E>> f = (acc, v) -> acc.cons(v.fail());
   return fail(list.filter(Validation::isFail).foldLeft(f, List.nil()).reverse());
  } else {
   F2<List<A>, Validation<E, A>, List<A>> f = (acc, v) -> acc.cons(v.success());
   return success(list.filter(Validation::isSuccess).foldLeft(f, List.nil()).reverse());
  }
 }

代码示例来源：origin: org.functionaljava/functionaljava

/**
 * Map each element of a structure to an action, evaluate these actions from left to right
 * and collect the results.
 */
public static <S, A, B> State<S, List<B>> traverse(List<A> list, F<A, State<S, B>> f) {
 return list
   .foldLeft(
     (acc, a) -> acc.flatMap(bs -> f.f(a).map(b -> cons(b, bs))),
     State.<S, List<B>>constant(List.nil()))
   .map(bs -> bs.reverse());
}

代码示例来源：origin: novarto-oss/sane-dbc

@Test
public void foldLeft()
{
  FoldLeftSelectOp<Integer> fold = new FoldLeftSelectOp<>("SELECT * FROM MySqlTest_IDS", NO_BINDER,
      (x, rs) -> x + rs.getInt(1), 0);
  Integer result = DB.submit(fold);
  assertThat(result, is(0));
  DB.submit(insertKeysOp(asList("a", "b", "c", "d")));
  Integer expected = DB.submit(new SelectOp.FjList<>("SELECT ID FROM MySqlTest_IDS", NO_BINDER, x -> x.getInt(1)))
      .foldLeft((x, y) -> x + y, 0);
  result = DB.submit(fold);
  assertThat(result, is(expected));
}