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Matt Parsons
17.6K posts
Matt Parsons
@mattoflambda
Haskell jock. Backend Developer UX at @mercury. I wrote @prodhaskell so you can get a Haskell job!
Denver Katılım Şubat 2013
597 Takip Edilen5.3K Takipçiler
the benchmark found that there was very small benefit going over -j16, and both -j8 and -j12 performed pretty damn well with much less memory use
the cool thing here is that we can now effectively have two ghci sessions on separate branches- big win with an AI agent!!
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ran a matrix of `-j` and `-A` values with ghc and ghci builds of the codebase
bigger -A values always improve perf substantially, but you increase resident memory: effectively, `-j * -A` nursery size.
-j32 * -A2GB causes OOM even on my 128GB RAM laptop
fortunately...
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weekend project: tuning the RTS parameters for GHC on our build.
result? 20% speedup and 20% less memory use
tl;dr:
* `-j` is probably wasteful on modern hardware - I see little benefit over -j16 and significant memory cost
* bigger -A values make a huge difference
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Matt Parsons retweetledi
Memory Palace@GreenBeans80277
@chrislakin idk if this is familiar, but I have tracked when techniques fail/succeed, and when they do succeed they only succeed once. Self-CBT fixed my depression for years once, but it never worked when it came back. “Just one more day” worked for 3 months, but never again after 1 fail.
ZXX
counterintuitively effective upgrades:
- coffee grinder cost more than espresso machine
- fancy wheels cost more than bike frame
- bow cost more than cello
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need more laptop stands throughout my house so i can multitask more effectively
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grew up kinda poor and have always clocked "International Travel" as impossibly expensive
and i mean it isn't *cheap*, still, but a round trip flight from Denver to Rome starts at $1,200
tix for classical music are like half price too
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@nosilverv Way too much exploring to be done to be exploiting yet
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far too little metis around vibecoding etc. tools are insane, AND NEW! We're in a global scientific project together of figuring out wtf they can do ("tools", lol) but we're not sharing research notes!!
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Matt Parsons retweetledi
Friends, I'm opening a spiritual center in Boulder!
It's called Nameless Mountain, and it's focused on spiritual maturity rather than enlightenment.
We're trying to raise $50,000 to cover this year's expenses. Please help build this with us by donating or becoming a member:
givebutter.com/nameless-mount…
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@marunarh @haskellfound What LLMs have you tried with Haskell?
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@mattoflambda @haskellfound I see, thank you! I haven’t tried them yet (with tooling enabled) for coding capabilities and “agentic” experience
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@haskellfound have you considered training LLM on the entire Hackage by yourself? How much disk space is taking Hackage?
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@marunarh @haskellfound Claude/ChatGPT/Gemini - the big commercial labs doing training. Open source code repositories are just an obviously fantastic resource for training, and I imagine that a lab is going to be going after any source of training tokens they can find.
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@mattoflambda @haskellfound Ah, what do you mean by “any major LLM”?
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some people use AI as a therapist
the AI uses me as a therapist
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Matt Parsons retweetledi
One of the cool thing about the AI revolution is that spending a lot of effort on error messages is cool again, because the agents actually read the error messages!
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Matt Parsons retweetledi
New blog post: "A sufficiently detailed spec is code"
I wrote this because I was tired of people claiming that the future of agentic coding is thoughtful specification work. As I show in the post, the reality devolves into slop pseudocode
haskellforall.com/2026/03/a-suff…
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"let's check out a new branch and pwn those nubs" what the fuck am i saying
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Matt Parsons retweetledi
NixCI is getting a cool suite profile view that lets you see why your CI is as fast/slow as it is.
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coloradomusicfestival.org/calendar/ Holy shit this is a good lineup
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Colorado Ballet rendition of Midsummer Nights Dream is fantastic
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