It seems as if the values inside the second and third pair of brackets are indexing into the list defined inside the first pair. The '+' operator converts the characters '0' and '1' into their integer representations.

Please help me understand the replacer function used in the decodeBits function. This syntax is really tripping my mind. I've never seen anything like this so I would like to understand it. For example, it looks to me to be a 3D array: s => [...][...][...].

It looks like the:

• first dimension is simply defining an array with 2 objects, one for the replacement spaces and the second the replacement dot and dash.
• second dimension appears to simply be getting the first character of the matched group, so either a 0 or a 1. But I don't understand what the + symbol is doing there.
• third dimension is dividing the matched group by the time unit.

Can you tie all this together for me, or point me in the direction of some reading material so I can wrap my head around this? I don't even know what to search for to google it!

This is my favorite solution I've seen thus far. Very nice and understandable implementation. Clever!

Nice usage of a tail recursive function. Beautiful solution.

Very nice solution!