## Monday, December 1, 2014

### Readability

I have written before about some of the differences between Ruby and Python and my quirks generally tend to the Ruby approach. I think readability is another dimension between the two languages that highlights this for me - especially as it applies to understanding new code.

I prefer to read code from left-to-right (LTR), top-to-bottom. This is natural for me as it models how I read other text. Code that processes right-to-left (RTL) and, in the severe case, bottom-to-top challenges my ability to easily understand intent. Method chaining highlights this quite nicely. For example, to transform the numbers of a list stored as a string in Python one might write:
','.join(map(lambda x : str(int(x) ** 2), "1,2,3,4".split(',')))

If I am reading that for the first time I need to mentally maintain a stack of operations (join, map, lambda) until I've parsed most of the statement and arrived at the object being operated on: "1,2,3,4". This is due to the RTL application of the code. I've then got to backtrack over each operation on my mental stack to understand what the type and/or result of the overall statement will be. This is complicated by the fact that Python allows for some LTR ("1,2,3,4".split(',')) mixed with the RTL.

For first-time readers of the language this process is even more difficult if the behavior of join or map are not yet well understood.

Ruby makes this significantly easier.
"1,2,3,4".split(',').map { |x| x.to_i ** 2 }.join(',')

When I read code similar to that I can store the type and result as I am parsing the statement. The initial object is immediately available and I can read the expression LTR as: split a string, apply a function to each element of the resulting array, and join that final array with the comma character. The fact that Ruby supports method chaining (on the built-in types) makes for much more readable code.

I've singled out Python above but that was only for the sake of the example. As far as RTL languages go I think Python is middle of the road. Haskell, for example, has a much nicer syntax to deal with function composition (a similar, but not identical situation). On the other end of the spectrum is Lisp which is basically a bottom-to-top, RTL language.

I can (and have) used these languages and many more; RTL vs. LTR in no way prevents one from being proficient over time. Certainly, most RTL code can be written in a way that it flows mostly LTR, top-to-bottom. Even when it isn't, well-written code can read by anyone with enough practice. For newcomers looking to read a new language however, there is less difficulty when the process more closely models how they read in general.