Accumulate

Instructions

Implement the accumulate operation, which, given a collection and an operation to perform on each element of the collection, returns a new collection containing the result of applying that operation to each element of the input collection.

Given the collection of numbers:

• 1, 2, 3, 4, 5

And the operation:

• square a number (x => x * x)

Your code should be able to produce the collection of squares:

• 1, 4, 9, 16, 25

Check out the test suite to see the expected function signature.

Restrictions

Keep your hands off that collect/map/fmap/whatchamacallit functionality provided by your standard library! Solve this one yourself using other basic tools instead.

For this exercise the following F# feature comes in handy:

• Tail recursion Prevent stack overflows with large input by using tail recursion. While there are no test cases checking explicitly for this, using tail recursion leads to a more performant solution. Another good resource on tail recursion is this blog post.
• Type inference The F# compiler can automatically infer types, which means you often don't have to add any types at all. For more information on how this works and its advantages, see this page.

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Source

Conversation with James Edward Gray II