This exercise focuses on adding methods to the Array class in Crystal.
To do this you will have to define a class with the name Array(T).
And put the methods inside this class.
class Array(T)
# your solution here
end
The array class is a generic class, it is also indexable and enumerable.
The source code for the Array class can be found here.
Implement the keep and discard operation on collections.
Given a collection and a predicate on the collection's elements, keep returns a new collection containing those elements where the predicate is true, while discard returns a new collection containing those elements where the predicate is false.
For example, given the collection of numbers:
And the predicate:
Then your keep operation should produce:
While your discard operation should produce:
Note that the union of keep and discard is all the elements.
The functions may be called keep and discard, or they may need different names in order to not clash with existing functions or concepts in your language.
Keep your hands off that filter/reject/whatchamacallit functionality provided by your standard library! Solve this one yourself using other basic tools instead.
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