# Opinions on SPy?
**URL:** https://discourse.julialang.org/t/opinions-on-spy/137591
**Category:** Offtopic
**Created:** [June 12, 2026, 8:08pm UTC](https://discourse.julialang.org/t/opinions-on-spy/137591 "2026-06-12T20:08:55Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@sylvaticus](https://discourse.julialang.org/u/sylvaticus)
#### Post date: [June 12, 2026, 8:08pm UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/1 "2026-06-12T20:08:55Z")
Had anyone tried [SPy](https://github.com/spylang/spy), yet another python-like interpreter/compiler (motivations [here](https://antocuni.eu/2025/10/29/inside-spy-part-1-motivations-and-goals/)) ?
What’s your thoughts about it ?
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### Author:  [@madppiper](https://discourse.julialang.org/u/madppiper)
#### Post date: [June 12, 2026, 8:20pm UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/2 "2026-06-12T20:20:54Z")
I think it is an interesting take on the language and hope it delivers only a fraction of what it claims. Nowadays I write a lot of Python simply because many dependencies are in that language and it is easier to prototype with it. But performance is a huge drawback. So if the projects succeeds on that, I’d be using it for many of my projects.
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### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [June 13, 2026, 12:06am UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/3 "2026-06-13T00:06:57Z")
Yet another [Mojo](https://mojolang.org/)-like project?
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### Author:  [@heliosdrm](https://discourse.julialang.org/u/heliosdrm)
#### Post date: [June 13, 2026, 7:32am UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/4 "2026-06-13T07:32:09Z")
Some people already made that question:
> **[SPy and Mojo: first impressions vs. deeper reality - My SPy Book](https://fluiddyn.pages.heptapod.net/spy-book/versus-mojo/)**
(By the way, I appreciate the transparency of the author about their using LLM for the creation of the content.)
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### Author:  [@Benny](https://discourse.julialang.org/u/Benny)
#### Post date: [June 13, 2026, 10:56am UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/5 "2026-06-13T10:56:20Z")
Unsurprisingly, the LLM-generated comparison with Mojo uses obsolete information: `let` was gone in 2024, and the increasingly redundant `fn` was deprecated this year at the cost of making `def` require manual opt-in for raising exceptions (though the official release was a week after that comparison was generated). I can appreciate that SPy doesn’t bother to be a Python superset, which Mojo has pivoted away from, and I think SPy being a public-facing derivative of PyPy’s internal RPython is interesting. If a stronger yet intentionally incomplete overlap with Python is of interest, Codon is a fun read.
The only Pythonish “language” I’ve had to use in practice is Numba (in quotes because Numba compiles a Python subset with slightly yet importantly different semantics, in other words there is no diverging syntax), but I get the same takeaway from all of them: optimizing Python semantics is so intractable that people keep tweaking the language or semantics to varying degrees for new front-end compilers with improved Python integration, relative to using established languages like C.
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### Author:  [@JeffersGlass](https://discourse.julialang.org/u/JeffersGlass)
#### Post date: [June 24, 2026, 6:16pm UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/6 "2026-06-24T18:16:24Z")
SPy contributor here (not Antonio, our fearless leader; I mostly work on docs/testing/CLI). Just wanted to note one thing that I think differentiates SPy from other “Python Subset/Superset/close-cousin-but-its-compiled” variants is the interpreter.
SPy is built in such a way that you get identical semantics whether running in the interpreter (currently written in Python, pretty slow) or compiled code. But unlike, say, Numba, where debugging means attaching `gdb`, SPy can just use `breakpoint()`. It has a debugger (`spdb`) that’s similar to Python’s. We’re working on a proper REPL. It’s trying to give the developer experience of an interpreted language with the performance of a compiled one.
A lofty goal for sure! But I find it an exciting idea and it’s been a fun project to work on.
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### Author:  [@stevengj](https://discourse.julialang.org/u/stevengj)
#### Post date: [June 24, 2026, 6:22pm UTC](https://discourse.julialang.org/t/opinions-on-spy/137591/7 "2026-06-24T18:22:10Z")
> [@JeffersGlass](#):
>
> A lofty goal for sure! But I find it an exciting idea and it’s been a fun project to work on.
Thanks for posting! We’re excited to see where things go with SPy.