Added the (..) function as an alias to range.

[jdantonio]

Page 38 of the Leanpub book (version published on 2014-08-16) defines a (..) function that is an alias for range. The book then uses this function repeatedly in following examples. This PR adds this function to the Data.Array library.

[jdantonio]

I'm new to PureScript so I apologize if this function appears somewhere else in the standard library and I have simply missed it. I've been programming primarily in Ruby for several years now and this is the notation that Ruby uses for creating a Range object. I find the syntax very intuitive and feel it leads to very expressive code.

[garyb]

I suppose the only downside of adding this is it would mean having to change the book to use import Data.Array hiding ((..)), and then redefining it which might be a bit odd.

I'll let @paf31 weigh in though. :)

[jdantonio]

@garyb Thank you for the feedback. That's a very good point, which I hadn't thought of at first. But after reading your comment I went back to the book and discovered that it does something very similar with the length function. On page 35 the book has an example which creates a length function using recursion and null:

import Data.Array (null)
import Data.Array.Unsafe (tail)

length :: forall a. [a] -> Number
length arr =
  if null arr
    then 0
    else 1 + length (tail arr)

This has the same signature as length from the standard library, but a very different implementation. So irrespective of what @paf31 decides about (..), an update to the book regarding redefining and hiding methods may be helpful.

[paf31]

I think this would be useful. I'd just need to change the wording in the book a bit. I'll be doing a release of the book later today, so it's no big deal. Thanks!

[paf31]

We can just say (..) = range since we're in the same module.

[jdantonio]

I've updated the function definition based on the suggestion from @paf31.

[paf31]

Thanks! 👍