Just the branch predictor gains are probably worth it.
TL;DR in one sentence:
"the loop runs without a branch, and is a candidate for vectorization".
That's it, that's the article. This matters a lot in huge-scale / scientific computing / HPF, where if you can express something as an operation on vectors on matrices, you win big (those ops parallelize well, can be run on GPUs, clusters, what have you).
I have always phrased this as "Never do one of something".
[dead]
Didn’t see it mentioned in the article but isn’t leading with if-statement called a “guard clause”. I like that pattern but it’s just general best practice I thought.
Swift explicitly has a guard statement for this. Rust's let .. else { ... } is also very similar.
https://docs.swift.org/latest/documentation/the-swift-progra...
Guard clauses are things that return early for trivial or problematic cases. Like https://en.wikipedia.org/wiki/Guard_(computer_science)#Flatt...
They're one of those good practices that look like bad practice to everyone who just got a CS degree. Seems ex-students are unsettled by asymmetry or want to minimize the number of return statements.
What is missing here is any benchmarks backing up this argument for code structure.
Of note, as of C#9 (and maybe prior), the dotnet runtime does this automatically whenever it is deemed safe. https://devblogs.microsoft.com/dotnet/performance-improvemen...
The same technique is applied as an optimization, when deemed safe, in all current gen c compilers (gcc, llvm, etc).
I'm very confused why neither measurements nor references to when this is done automatically in most modern languages is included in the article.
At least in JVM land, it's pretty easy to thwart that optimization. Particularly if the condition is on a mutable yet unchanged in the loop value.
For example:
var map = new HashMap<String, String>();
map.put("foo", "bar");
for (var i : items) {
if ("bar".equals(map.get("foo")) {
doStuff(i);
}
}
I like it, but to do fizzbuzz in this way, you'd have to separate what's inside the loop into a reused function.
Or just use lazy list operations with a single if test at the end:
https://github.com/taolson/Admiran/blob/main/examples/fizzBu...
/s
I think it's sort of obvious that the limit to this general rule is when data dependencies between fors and ifs forbid you from pushing things further up/down.
I've done this for years. Not every time of course but where it makes the code easier to understand and maintain.
Speed was almost never the reason.
I take it you never rewrote a Matlab for loop as a vector/matrix op for insane speedups then :)
I am continually impressed by the ability of LLMs to take trivial ideas and turn them into lengthy and obtuse blog posts with unnecessary analogies.
Honestly, this just looks like one of those lingo-heavy-but-surface-level blog posts that used to make functional programming spaces so insufferable to everyone on the outside
These things are so divorced from the reality of programming, even when they involve actual code instead of fancy lingo. Like in Scala, not a pure functional language, tutorials used to find the most convoluted higher-order functional way to do simple things.
Yet another encroachment on traditionally human activity.
I am the
Option<Walrus>I know we’re not supposed to comment just for that, but this might be my single favorite joke comment I’ve ever read here. Good job.