There are a couple of things I see which influence the typographic decisions regarding the code. First is its size - not really big enough to justify a data abstraction for the strings forming regex's. Being standalone, there is a justification for inlining these that would not be there for a similar snippit from part of a larger system.
A second feature appears to be optimizing the layout to display in "forty lines." There are places where the lines could be shorter but aren't. Not abstracting the strings falls somewhat into this category.
Finally, the code snippet does not appear to be the output of a pretty printer. Instead the typography is based on considerations beyond readability.
Comments
There are a couple of things I see which influence the typographic decisions regarding the code. First is its size - not really big enough to justify a data abstraction for the strings forming regex's. Being standalone, there is a justification for inlining these that would not be there for a similar snippit from part of a larger system.
A second feature appears to be optimizing the layout to display in "forty lines." There are places where the lines could be shorter but aren't. Not abstracting the strings falls somewhat into this category.
Finally, the code snippet does not appear to be the output of a pretty printer. Instead the typography is based on considerations beyond readability.