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CHAINING.md

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Chaining:

The most basic picopattern is the fishead operator: chaining the result for a function to another function.

    value val1 = method1(initialValue);
    value val2 = method2(val1);
    value val3 = method3(val2);

Chain start

If you already read the readme page, you probably already known how to start a chain. The chain top-level method does it for you:

    value ch = chain(initialValue);

Chain steps

Once the chain has started, you can chain more functions by using the to method. This method requires the type returned by the previous function (also known as the type returned by the previous chain, or the incomming type) satisfy the type for the new function parameter(s). In other words, the following is accepted:

    Integer(Integer) method1 = Integer.successor;
    String(Integer) method2 = Integer.string;
    chain(1).to(method1).to(method2)

But this is not

    Integer(Integer) method1 = Integer.successor;
    Integer(String) method2 = String.size;
    chain(1).to(method1).to(method2); // ERROR!

Because method2 expects and String, but method1 provides an Integer.

Utility methods

Almost sure, every time you start a chain, you will provide (at least) one method to be applied onto initial values. So probably you will write something like:

    chain(initialValue).to(initialMethod)...

An utility method is provided to save you some strokes: chainTo

    chainTo(initialValue,initialMethod)...

This chain is equivalent to the chain(...).to(...) counterpart, but some people find it clearer. Use the one more appealing to you.

END

And that's all about basic chaining! This is the most basic tool you will use from this library. Next chapter we will talk about how to introduce functions into a chain, without retaining its value.