Evan Czaplicki

@evancz

Creator and developer of @elmlang
Reading highlights at @power_studies

elm-lang.org Joined October 2012

68 Following 17K Followers 3.3K Posts

Latest posts 5

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Evan Czaplicki @evancz Jun 23, 2025

Many programmers would love to use "productivity languages" like @elmlang, but what about the business person who often makes the final decision?

How can we rethink our strategies such that authors, developers, and businesses grow stronger together? 🔄

youtu.be/YPAaUFGrlEE

www.youtube.com Keynote: Rethinking our Adoption Strategy - Evan Czaplicki | Lambda Days 2025 ✨ This talk was recorded at Lambda Days in June 2025. If you're cur...

Evan Czaplicki @evancz 7h

Me when I want to avoid unexpected JSON so much that I write a typed functional query language.

"Tony Hoare told me to do it in 1973!"

$A final hint: listen carefully to what language users say they want, until you have an understanding of what they really want. Then find some way of achieving the latter at a small fraction of the cost of the former. This is the test of success in language design, and of progress in programming methodology. Perhaps these two are the same subject anyway.$

Evan Czaplicki @evancz 1d

Dijkstra on testing vs language design:

"For what program structures can we give correctness proofs without undue labor?"

With @elmlang you get:
- no null pointers
- no unhandled exceptions
- no aliasing bugs
- safety from supply chain attacks

AND it's more fun than JS/TS 😅

Dijkstra points out, exhaustive testing of a computer program is virtually impossible, and testing by "sampling" also is pointless. As he says, "Program testing can be used to show the presence of bugs, but never to show their absence!" And, while rigorous mathematical proofs of program correctness are possible, they are difficult to construct, often because the programs themselves are not well suited to such analysis. So, as Dijkstra explains, rather than first writing a program and then worrying about the difficult task of constructing a proof of program correctness, it makes far better sense to ask, "For what program structures can we give correctness proofs without undue labour..." and then, "How do we make, for a given task, such a wellstructured program ?"

Evan Czaplicki @evancz Oct 30

Going to be in NYC in November. Come to my talk at @recursecenter if you are around!

luma.com/rc-acadia

luma.com Evan Czaplicki: Dragging SQL into the 1990s · Luma Come to Localhost at the Recurse Center! Localhost is a series of technical talks in NYC given by members of the Recurse Center community. For every event, we…

Evan Czaplicki @evancz Oct 27

Making progress on the @elmlang 0.19.4 upgrades. Compiler improvements usually touch a high % of modules, so [128 of 153] means it's coming along nicely!