Parallelize all the things -- Deconstructing Haxl, with Clojure macros, topological sorting and Quasar fibers

Parallel Lines

Select, few

Recently, there's been a lot of interest in DSLs to address the so-called N+1 selects problem, which describes the very common situation where you

  1. Do one database query to get a list of things, say user IDs;
  2. for each, call some sort of processing function that happens to
  3. do another query, say for each user's name.

It can be even worse than that, as in this example, where (for some reason) we want to append the last name of every person in a group to the first name of their best friend. (Maybe they're ...

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Scala Partial Functions Are Disgusting and Unnecessary

Thou whoreson zed! thou unnecessary letter!

- King Lear, 2.2.61

Partial functions are great in theory. By "great in theory", I mean that the basic idea is pretty simple but with very little additional research you can make weighty pronouncements involving the words "in" and "theory", as in, "in category theory, something something surjective algebra manifold."

The simplest example of a partial function is something like the logarithm, which isn't defined for arguments less than or equal to zero. Of course, it's also not defined for arguments that are strings or colors or egg-laying mammals, a restriction ...

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Notes on Horrible Code

Recently, I came across some horrible, horrible code. I immediately pasted it into a messaging application and quickly received an expression of solidarity. With what though? My indignation? Grief? Amusement? I find it suspicious that code I consider horrible tends to have been written by people I already disliked for some reason.

Here are some things I have complained about recently:

  1. Code that was the source of a bug that was in retrospect obvious.
  2. Code that could be deleted with no change to the behavior of the program other than, possibly, a performance improvement.
  3. Extremely inefficient code, perhaps extravagant in ...
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