November 1, 2025
Regex drama, served hot
The Impossible Optimization, and the Metaprogramming to Achieve It
Dev touts “impossible” speed boost — commenters argue Mojo, C++, or just check Gmail
TLDR: A post touts huge speedups by auto-generating code for email checks, but commenters fire back: prior art in C++, unclear that it’s written in Mojo, and plenty of “just keep it simple” tips like checking for Gmail. It matters because it spotlights clever compilers versus practical shortcuts.
A dev claims a wild “impossible optimization”: use metaprogramming (code that writes code) to turn a slow, general regex for email checks into super-specific code — and it flies. Sounds epic, right? The comments immediately split into camps. One camp flexed receipts: “we’ve done this,” pointing to C++’s compile-time regex magic via this library. Another camp asked, um, what language is this? Turns out it’s Mojo, but the post barely says so, which had readers rolling their eyes at the mid-article reveal.
Then the pragmatists crashed the party. One commenter joked that the fastest fix is just to check if an email ends in “@gmail.com,” and even suggested splitting the email at the “@” and scanning both sides in parallel. Meanwhile, a math warrior dropped a tale about deleting “two transposes in a row” and unlocking ridiculous speed — the vibe: big wins come from killing pointless work. Nostalgia also hit: someone cheered a Lisp shout-out, while others argued a JIT (a just-in-time optimizer) could do similar tricks—so why all the ceremony?
The mood? Half awe, half “seen it,” with a sprinkle of “Mojo-dojo mystery language.” It’s the classic internet brawl: fancy compiler sorcery versus “keep it simple, please,” and the memes write themselves: optimize all the things… or just whitelist Gmail and go home.
Key Points
- •The article argues metaprogramming can deliver large performance gains, beyond typical template-based expectations.
- •It uses an email validation regex to demonstrate common matching behavior and correctness across inputs.
- •Regex is characterized as slow due to interpreter overhead; precompiled regex using AST or DFA still adds interpretation costs.
- •A hand-written matcher example shows explicit character-class checks and manual control for speed.
- •The piece sets up metaprogramming as a way to generate specialized code that achieves significant optimizations.