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15-212: Principles of Programming |
Continuations act as "functional accumulators." The basic idea of
the technique is to implement a function f by defining a
tail-recursive function f' that takes an additional
argument, called the continuation. This continuation is a
function; it encapsulates the computation that should be done on the
result of f. In the base case, instead of returning a
result, we call the continuation. In the recursive case we augment
the given continuation with whatever computation should be done on the
result.
Continuations can be used to advantage for programming solutions to a variety of problems. In today's lecture we'll look at a simple example where continuations are used to efficiently manage a certain pattern of control. We'll see a related and more significant example in an upcoming lecture when we look at regular expressions.
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