Over the last couple of yorgey lectures, we have seen how the Applicative class allows us to idiomatically handle computations which take place in some sort of "special context" -- for example, taking into account possible failure with Maybe, multiple possible outputs with [], consulting some sort of environment using ((->) e), or construct parsers using a "combinator" approach, as in the homework.

However, so far we have only seen computations with a fixed structure, such as applying a data constructor to a fixed set of arguments. What if we don't know the structure of the computation in advance -- that is, we want to be able to decide what to do based on some intermediate results?

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