Regex visualized as 3D marble run(regexmarblerun.com) |
Regex visualized as 3D marble run(regexmarblerun.com) |
Let's be honest, regex can be hard to understand even for technical people. (At least it's hard for me.)
So coworker built this to help anyone understand arbitrary regex commands.
AI disclosure: this was built using Agent Duel, a local coding agent arena system (https://github.com/bottomless/agent-duel). Promotion disclosure: our company is building agent duel. To test it and find bugs we are building passion projects through the system. I nonetheless thought HN would find this interesting.
But regex is also syntactically designed by Satan himself.
Most programming languages use commands that are semantically understandable, like "for" and "let" and "return" and mostly symbols we already know like "+" and "=". They use newlines and indentation for organization. And they put multiple commands on multiple lines and you can add comments and everything.
Regex is exclusively punctuation, with its own idiosyncratic meanings, all compressed into a single line, zero organization, zero comments, and impossible to remember what each symbol does if you don't use it daily. Not to mention the nightmare of escaping regexes when expressed as strings, on top of escaping regex symbols within the regex itself.
I swear it's high time we come up with a regex replacement that looks like normal Python code or HTML or something. So instead of:
^(\+\d{1,3}-?)?\d{3}-\d{3}-\d{4}$
<start>
<optional> # Optional country code
"+"
<digit>[1-3]
"-"
</optional>
<digit>[3] # Area code
"-"
<digit>[3]
"-"
<digit>[4]
<end>
^(?P<country_code>\+[0-9]{1,3}-?)?[0-9]{3}-[0-9]{3}-[0-9]{4}$
^
(
\+
[0-9]{1,3}
-?
)? # optional country code
[0-9]{3}
-
[0-9]{3}
-
[0-9]{4}
$
Ultimately it is a dsl. Should equations in math also use full words and comments?
No, they should not. Maybe a nice syntax for grammars like raku is a better approach.
Personally, I like regexes, in the same way that I like shell string manipulation: it looks utterly inscrutable, and performs magic. If I write one in code meant for others, I usually use extended mode with each line commented.
The problem IMO is that a lot of the traditional teaching material starts with the complexity (and impressive possibilities) of regex, when the best way to start learning it is probably just thinking about it as an extension to simple text matching.
Getting to know regex fully is in fact complicated, getting know enough regex to filter/search/replace 90% of everything you will always need is not too complicated.
.
|
?
*
+
()
??
*?
+?
So while I think it's a worthwhile suggestion not to show people the whole thing the first time round, I doubt that the whole thing is really that complicated.
"|", which means "or"
".", which means "any symbol"
"?", which means "at most once",
"*", which means "however many times"
"+", which means "at least once"
The foundation is in theoretical CS with deterministic and nondeterministic finite automata (DFAs and NFAs), and I found it easiest to teach regexes using DFAs since you can then just draw circles and arrows. Regex notation is just a different notation. It's a bit likeif you know piano and then learn another instrument, your brain can always refer back to the piano and it's all much easier.
Backreferences are not really "controversial" but just an extension which does not map to regular languages (those recognized by finite automata). That is, they make regexes "non-regular", so they are more a hack. Regex engines that want to support them need a fundamentally different approach, that's why some don't support them and in principle will never be able to.
Also, it's important for people not to confuse backreferences with capture groups. They look a bit similar, but capture groups are actually fine.
In fact, backreferencing is such a footgun that I don't see it as a possible regex feature. It's a PCRE feature - perhaps even the core distinguishing feature. While all regexes are PCREs, not all PCREs are regexes. It's simply not possible to create a consistently performant implementation of PCRE.