Effective Haskell

Exercises

traverseDirectoryIO

Write a new function, traverseDirectoryIO, that has the type:

traverseDirectoryIO :: FilePath -> (FilePath -> IO a) -> IO [a]

This function should behave like traverseDirectory’ but should accept a function returning an IO action, rather than a value.

Timing Pure Functions

The timeFunction that you built as you worked through this chapter only supports timing IO actions. Try writing a version of this function that also works for pure values, with the type:

timePureFunction :: Metrics -> String -> a -> IO a

What are the limitations to your implementation function? Are there things that a user of the function could do to ensure that the timing information was better?

Metrics Strictness

Consider the ...