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mathspp.com
Rodrigo Girão Serrão 🐍🚀
@mathspp.com
1.1K followers 310 following 1.2K posts
I'll help you take your Python skills to the next level!

Python deep dive every Monday 🐍🚀 -> https://mathspp.com/insider

Short daily drop of Python knowledge 🐍💧 -> https://mathspp.com/drops
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mathspp.com
FINALLY had technical issues while delivering a remote talk.

Today I got all of it!

First, my computer froze and I couldn't even share my screen.

Then, at some point my internet connection went POOF and I dropped off the call... 🤦

Hopefully now I'm good again for a dozen more talks.
February 12, 2026 at 7:35 PM
mathspp.com
Catch you there?
February 12, 2026 at 10:49 AM
Reposted by Rodrigo Girão Serrão 🐍🚀
savannah.dev
Stoked to share that the Steering Council has accepted PEP 814. frozendict is coming to Python 3.15!

discuss.python.org/t/pep-814-ad...
PEP 814: Add frozendict built-in type
After careful deliberation, the Python Steering Council is pleased to accept PEP 814 – Add frozendict built-in type. The absence of an immutable dict counterpart has been a long-standing gap in Pytho...
discuss.python.org
February 11, 2026 at 5:13 PM
Reposted by Rodrigo Girão Serrão 🐍🚀
python.org
Introducing the PSF Community Partner Program! The PSF is very excited to announce this new in-kind offering that expands how we support Python community events and initiatives around the world, now and alongside future community support programs 💝🐍
Introducing the PSF Community Partner Program
The Python Software Foundation (PSF) is excited to announce the introduction of the PSF Community Partner Program. This new program is designed as an “in-kind” way for us to support Python events and initiatives with non-financial assistance through the use of the PSF logo and name, as well as promotional support via sharing qualified posts on PSF official social media accounts. The PSF looks forward to supporting Python community events and initiatives through this new program!The introduction of the PSF Community Partner Program grew out of our desire to find alternative ways to support the community during the pause of our Grants Program (read more about the resulting process below). Even so, we intend to continue offering this in-kind support program after the Grants Program reopens. Our big picture hope is that, over the long term, some community events and initiatives will continue to partner with the PSF while being financially dependent on sponsors and individual donors alone. The PSF is also working on the future of our Grants Program, including when and how we can reopen it in a way that ensures the program’s long-term sustainability while balancing the needs of the Python community. In light of the truly staggering outpouring of support from our community during the 2025 year-end fundraiser, we are now in a stronger position to reopen the Grants Program and are eager to give back in a thoughtful and sustainable way. More updates to come!As with the rollout of any new program, we anticipate small adjustments will need to be made for processes to flow smoothly and to ensure the program serves the Python community well. The PSF welcomes your comments, feedback, and suggestions regarding the new Community Partner Program on the corresponding Discuss thread. We also invite you to join our upcoming PSF Board or Grants Program Office Hour sessions to talk with the PSF Board and Staff synchronously. If you wish to send your feedback privately, please email grants@python.org. 
pyfound.blogspot.com
February 10, 2026 at 2:13 PM
mathspp.com
This list is missing the soft keywords.

How many are there, and what are they?
teachmepython.bsky.social teachmepython.bsky.social @teachmepython.bsky.social · 3d
Here's a list of the #Python keywords

It's nice that the number is so small that you can actually probably remember all of them fairly easily.
February 9, 2026 at 5:30 PM
mathspp.com
I've written this Python function so many times I should no longer be confused by it...

But I never know if it's

def clamp(v):
return min(max(v, low), high)

or

def clamp(v):
return min(max(v, high), low)

Always need to stop and think about it for a minute.
February 9, 2026 at 4:48 PM
mathspp.com
If they had used the built-in `range` this wouldn’t happen.
Photo of a set of buttons inside an elevator. From the bottom up, the numbers go 2, 0, 4, 5, 6, …
February 3, 2026 at 12:13 PM
mathspp.com
It's pretty cool how much you can get done in Python with so little code if you leverage the standard library.
Python code snippet with the following code: from collections import deque from itertools import islice, tee def nwise(iterable, n): iterators = tee(iterable, n) for offset, it in enumerate(iterators): deque(islice(it, offset), maxlen=0) yield from zip(*iterators)
February 2, 2026 at 5:54 PM
mathspp.com
One of my students today made this mistake.

If you have a project and want to test it, your tests will import your project.

So, you need to install pytest as a dependency INSIDE your project.

If you install it globally, when you run it, it can't see your own project.
Diagram showing how using uv to install pytest globally will isolate it from everything else, as it should. But if you're testing a package, you want to have pytest as a dependency of that package since it'll be able to find your own package code.
January 30, 2026 at 9:28 PM
mathspp.com
Dump JSON and make it Human-readable.
Diagram showing how using the parameters `indent` and `sort_keys` can make the output of dumping JSON much better in Python.
January 30, 2026 at 4:40 PM
mathspp.com
Parse JSON from a string with a single function call.

Don't use this if you have JSON in a file. Use `load` for that.

This is for when the data comes in a payload, for example.
Simple diagram showing how to use `json.loads` to parse a native Python object from a JSON string.
January 29, 2026 at 4:19 PM
mathspp.com
When writing CLIs and scripts for the terminal, use `sys.exit` to set the exit code of your program.

✅ An exit code of 0 means success; your program terminated without any issues.

❌ Any other integer exit code means “error”.
Diagram showing how to use `sys.exit` to set the exit code of a program and how to use the command `echo $?` to check the exit code of the last command in the terminal.
January 28, 2026 at 4:32 PM
Reposted by Rodrigo Girão Serrão 🐍🚀
europython.eu
“Nothing beats the smiles and thank you’s you get when the conference is over. Plus, it is an amazing feeling to be part of something bigger than yourself.”

Check out the interview with @mathspp.com, Programme Team for EuroPython 2025 blog.europython.eu/humans-of-ep...

#europython #conference
January 27, 2026 at 9:02 AM
mathspp.com
Day 2 of my intermediate Python course:

I didn't forget to start the recording.

That's a great start to the day :D
January 27, 2026 at 3:43 PM
mathspp.com
Before being added in Python 3.10, itertools.pairwise was commonly implemented in terms of itertools.tee.

Isn't this elegant?
Diagram showing how to implement pairwise in terms of tee. Code: def my_pairwise(it): it1, it2 = tee(it, 2) next(it2) yield from zip(it1, it2)
January 27, 2026 at 2:44 PM
mathspp.com
`typing.reveal_type` explained:

Runtime vs static type checking time.
The module `typing` provides a debugging aid, the function `reveal_type`. When a static type checker encounters it, the static type checker emits a note with the _inferred_ type of the expression passed into `reveal_type`: ```py def s() -> str: return 3 reveal_type(s()) # Revealed type is "builtins.str" ``` The function `reveal_type` doesn't even need to be imported and the static type checker infers that `s()` is a string because of the return type `-> str`. (The static type checker also complains about the fact that we're returning an integer from inside `s` while the function should return a string, but you'll see why I'm doing that in a second.) At runtime, the function `reveal_type` prints the runtime type of the argument to `sys.stderr` and returns the argument unchanged: ```py from typing import reveal_type def s() -> str: return 3 reveal_type(s()) # Runtime type is 'int' ``` At runtime, the type of `s()` is `int` because the function `s` returns the integer 3.
January 26, 2026 at 2:12 PM
mathspp.com
Python typing pop quiz.

Take a look at the function `choice` shown below.

Note how it's being called as `choice(3, "hey!")`.

Will this type check or not?

If it does, what's the revealed type?

The right answer might surprise you!
It surprised me. 🤷
Code listing with the following Python code: from typing import reveal_type import random def choice[T](left: T, right: T) -> T: if random.random() < 0.5: return left else: return right reveal_type(choice(3, "hey!"))
January 25, 2026 at 2:40 PM
mathspp.com
This is how you learn to write really good code.

In Python, and in any other programming language 👇
January 24, 2026 at 3:26 PM
mathspp.com
Has anyone here, in the data science world, successfully moved from using conda/miniconda/... to using uv?
January 23, 2026 at 10:09 PM
mathspp.com
Python has a flexible mechanism built into `pathlib` to look for files with filenames that follow a given pattern.

You can use `[...-...]` to represent character ranges and `*` to match arbitrary text.

But note that `glob` does NOT support regex syntax!
This is just similar.
Diagram showing how character ranges and the asterisk can be used in `pathlib.Path.glob` to match multiple filenames that follow the same pattern.
January 23, 2026 at 3:28 PM
mathspp.com
These two typing features look similar...

But they're very different.

Here's how to use NewType and TypeAlias in Python 👇
Diagram with code snippets showing how to use TypeAlias and NewType. The content of the post walks through the diagram.
January 21, 2026 at 4:27 PM
mathspp.com
Pandas 3.0.0 is out now!
Screenshot of the pandas 3.0.0 release on GitHub.
January 21, 2026 at 4:24 PM
mathspp.com
In hindsight, if you're seeing this on your phone, the QR code isn't very helpful...

Just go to mathspp . com / drops 🤣
mathspp.com Rodrigo Girão Serrão 🐍🚀 @mathspp.com · 23d
Just finished scheduling 3 tips for today, tomorrow and Friday.

If you want to get smarter about Python in just 3 min/day, follow the QR code to sign-up.
Screenshot of my newsletter scheduled posts showing three upcoming emails: typealias vs newtype, character ranges in glob search, and expanding regex matches. The image also includes a QR code that takes you to mathspp.com/drops where you can sign-up to get these tips.
January 21, 2026 at 1:11 PM
mathspp.com
Just finished scheduling 3 tips for today, tomorrow and Friday.

If you want to get smarter about Python in just 3 min/day, follow the QR code to sign-up.
Screenshot of my newsletter scheduled posts showing three upcoming emails: typealias vs newtype, character ranges in glob search, and expanding regex matches. The image also includes a QR code that takes you to mathspp.com/drops where you can sign-up to get these tips.
January 21, 2026 at 9:52 AM
mathspp.com
Convert data to a JSON string without writing to a file:

Just use `json.dumps`!

(The final S stands for String!)

```py
import json

data = {"k1": True, "k2": [73, 42, 10]}

s = json.dumps(data)
print(type(s), s)
# <class 'str'> {"k1": true, "k2": [73, 42, 10]}
```
Diagram showing how to use `json.dumps` to convert data into a JSON string. Code snippet: ```py import json data = {"key1": True, "key2": [73, 42, 10]} dumped = json.dumps(data) print(type(dumped), dumped) # str {"key1": true, "key2": [73, 42, 10]} ```
January 20, 2026 at 2:31 PM