Comment by simonw
18 hours ago
I'm not arguing for using LLMs as an abstraction.
I'm saying that a key component of the dependency calculation has changed.
It used to be that one of the most influential facts affecting your decision to add a new library was the cost of writing the subset of code that you needed yourself. If writing that code and the accompanying tests represented more than an hour of work, a library was usually a better investment.
If the code and tests take a few minutes those calculations can look very different.
Making these decisions effectively and responsibly is one of the key characteristics of a senior engineer, which is why it's so interesting that all of those years of intuition are being disrupted.
The code we are producing remains the same. The difference is that a senior developer may have written that function + tests in several hours, at a cost of thousands of dollars. Now that same senior developer can produce exactly the same code at a time cost of less than $100.
React is hundreds of thousands of lines of code (or millions - I haven’t looked in awhile). Sure, you can start by having the LLM create a simple way to sync state across components, but in a serious project you’re going to run into edge-cases that cause the complexity of your LLM-built library to keep growing. There may come a point at which the complexity grows to such a point that the LLM itself can’t maintain the library effectively. I think the same rough argument applies to MomentJS.
If the complexity grows beyond what it makes sense to do without React I'll have the LLM rewrite it all in React!
I did that with an HTML generation project to switch from Python strings to Jinja templates just the other day: https://github.com/simonw/claude-code-transcripts/pull/2
Simon, you're starting to sound super disconnected from reality, this "I hit everything that looks like a nail with my LLM hammer" vibe is new.
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That would go over on any decently sized team like a lead balloon.
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"React is hundreds of thousands of lines of code".
Most of which are irrelevant to my project. It's easier to maintain a few hundred lines of self written code than to carry the react-kitchen-sink around for all eternity.
Not all UIs converge to a React like requirement. For a lot of use cases React is over-engineering but the profession just lacks the balls to use something simpler, like htmx for example.
Sure, and for those cases I’d rather tell the agent to use htmx instead of something hand-rolled.
Core react is fairly simple, I would have no problem using it for almost everything. The overengineering usually comes at a layer on top.
Without commenting if parent is right or wrong. (I suspect it is correct)
If its true, the market will soon reward it. Being able to competently write good code cheaper will be rewarded. People don't employ programmers because they care about them, they are employed to produce output. If someone can use llms to produce more output for less $$ they will quickly make the people that don't understand the technology less competitive in the workplace.
> more output for less $$
That's a trap: it's not obvious for those without experience in both business and engineering on how to estimate or later calculate this $$. The trap is in the cost of changes and fix budget when things will break. And things will break. Often. Also, the requirements will change often, that's normal (our world is not static). So the cost has some tendency to change (guess which direction). The thoughtless copy-paste and rewrite-everything approach is nice, but the cost goes up steep with time soon. Those who don't know it will be trapped dead and lose business.
Predicting costs may be tricky, but measuring them after the fact it's a fair bit easier.
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A major difference is when we have to read and understand it because of a bug. Perhaps the LLM can help us find it! But abstraction provides a mental scaffold
I feel like "abstraction" is overloaded in many conversations.
Personally I love abstraction when it means "generalize these routines to a simple and elegant version". Even if it's harder to understand than a single instance it is worth the investment and gives far better understanding of the code and what it's doing.
But there's also abstraction meaning to make less understandable or more complex and I think LLMs operate this way. It takes a long time to understand code. Not because any single line of code is harder to understand but because they need to be understood in context.
I think part of this is in people misunderstanding elegance. It doesn't mean aesthetically pleasing, but to do something in a simple and efficient way. Yes, write it rough the first round but we should also strive for elegance. It more seems like we are just trying to get the first rough draft and move onto the next thing.
> Making these decisions effectively and responsibly is one of the key characteristics of a senior engineer, which is why it's so interesting that all of those years of intuition are being disrupted.
They're not being disrupted. This is exactly why some people don't trust LLMs to re-invent wheels. It doesn't matter if it can one-shot some code and tests - what matters is that some problems require experience to know what exactly is needed to solve that problem. Libraries enable this experience and knowledge to centralize.
When considering whether inventing something in-house is a good idea vs using a library, "up front dev cost" factors relatively little to me.
Don't forget to include supply chain attacks in your risk assessment.