Left-Fold in Java

Here’s my take on a left fold in Java. Calling it is somewhat verbose, but it does the job of abstracting iteration so you don’t actually have to write another for loop on Iterable as long as you live.

  public static <A, B> A fold(F<A, F<B, A>> f, A z, Iterable<B> xs)
    { A p = z;
      for (B x : xs)
        { p = f.f(p).f(x); }
      return p; }

In case it’s not obvious, F<A, B> is an interface with one method: B f(A a).

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