add strain

[BNAndras]

No description provided.

[glennj]

First, apologies for taking so long. I wasn't actually watching the repo so I didn't get notified about your PRs

Second, isn't this exercise generally deprecated in favour of list-ops?

Nevertheless, I'll review and merge when ready.

[glennj]

I think this would be more readable like:

Suggested change

	pending 'keeps strings', ->
	result = Strain.keep {'apple', 'zebra', 'banana', 'zombies', 'cherimoya', 'zealot'}, (x) -> starts_with x, 'z'
	expected = {'zebra', 'zombies', 'zealot'}
	assert.are.same expected, result
	pending 'keeps strings', ->
	list = {'apple', 'zebra', 'banana', 'zombies', 'cherimoya', 'zealot'}
	predicate = (x) -> starts_with x, 'z'
	result = Strain.keep list, predicate
	expected = {'zebra', 'zombies', 'zealot'}
	assert.are.same expected, result

and the prediate variable can be more descriptive, like

predicate = (str) -> starts_with str, 'z'
-- or
predicate = (sublist) -> contains sublist, 5
-- or
predicate = (_) -> true -- always true

I'll look at the generator

[BNAndras]

Yeah, I definitely agree. A little deviance from the problem specs names is fine if it improves readability.

[glennj]

First, apologies for taking so long. I wasn't actually watching the repo so I didn't get notified about your PRs

And I was coming here thinking about what new exercises to add, now that I've given you a turn ;)

[BNAndras]

Second, isn't this exercise generally deprecated in favour of list-ops?

You might be thinking of accumulate, which is deprecated in favor of list-ops. Only 17 tracks have that exercise still available while a total of 55 tracks have List Ops. Strain is present on 44 tracks and isn't deprecated. The filter functionality in List Ops is pretty similar to the keep functionality in Strain though, and overall List Ops is more interesting I think. However, Strain might still be useful as a simpler exercise leading into List Ops.