LucianU/fromIndex.hs

Last active August 9, 2018 10:50

Star 0 You must be signed in to star a gist
Fork 0 You must be signed in to fork a gist

Learn more about clone URLs
Clone this repository at <script src="https://gist.github.com/LucianU/1be522cba081617e3a37813bdd754812.js"></script>
Save LucianU/1be522cba081617e3a37813bdd754812 to your computer and use it in GitHub Desktop.

Download ZIP

Raw

fromIndex.hs

	fromIndex :: Int -> [a] -> Maybe a
	fromIndex 0 (x:xs) =
	Just x
	fromIndex index [] =
	Nothing
	fromIndex index (x:xs) =
	fromIndex (index - 1) xs

sshine commented Aug 9, 2018 •

edited

You don't need the [x] special case. (This doesn't work as a base case, since [] is not caught. Use [] instead.)
Your fromIndex' is only necessary to keep track of currIndex, but you could use index recursively and subtract from it.

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment