Pattern Matching in Python?

Python Enhancement Protocol (PEP) 622 proposes introducing support for structural pattern matching into Python 3.10, much like other functional programming languages like Haskell and ML. It's still a draft, and Python 3.10 is still more than a year away from an official release, but there's a working implementation to try! Here, I take a look at pattern matching in action.

0:00 PEP 622
0:46 Structural Pattern Matching
2:23 Extracting Values from Patterns
5:41 Guards
6:41 Maximum
8:56 Closing

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[edurz]

Incredible, you explain it in an easy to understand and fast way. Congrats

[abhisheksharma]

LOVE From Nepal .You explain so well Brian.

[immanuelsuleiman]

Very cool
Thank you for taking the time to explain this

[yash]

5:35 terminal bug right? the terminal didn't erase the content of the last TUI application. it happens a lot with me while using pagers (like less or info) etc

[khmsalhuas]

Where can i find the working implementation? I want to try it myself. Great video btw.

[alexeygutikov]

Love this! Terminal, vim and python - nothing extra.
Btw anybody knows if Python will optimize tail recursion in this example?

[yepee]

Wow, I didn't realize the robustness of pattern matching in Python. Silly ol me has been using it as a simple switch case.

[kazifaisal-rjjs]

Great video, pattern matching vs regex

[forsyth]

Welcome to the future! Anybody else come here to figure what pattern matching actually was?

[yash]

7:36 oh, it this the asterisk operator? which expands a list into its elements.
it's called spread in javascript, i don't know its name in python.

[GiniLoh]

This is what I really want it, thanks you so much

[deadeyea]

+ the useful use of assignment expression. The structural pattern matching feels very natural, except the case for all, which is a _. I hope it will be replaced with a *.

[kitebeachinnbeachinn]

Your voice sounds like Brian Yu from Harvard CS50, also the way you use Vim.

[allyourcode]

I am pretty skeptical of this feature, especially it's "bells and whistles" that go beyond a simple switch. Switch itself can often be done nicely using a dict literal. E.g.

{404: 'Not found'}.get(status_code)

or if you need something more advanced,

{404:

Combining match with the the walrus operator just makes it more unpleasant to me.

If you want the effect of an if statement, just use an if statement. E.g.

match command:
case ['eat', food]:
if is_animal_product(food):
raise VeganismViolation
deliver_to_mouth(food)
case ['speak', content]:
utter(content)

Don't be breaking animal products into its own case! The purpose of this match statement should be to branch on the type of command, not to handle all branching that the app might do. Again, we are reduced to something that could be handled using the "dict literal as switch" pattern:

op, arg = command
{'eat': handle_eat_command}[op](arg)

[lien]

As always with new features in python, let the opinion war begin...

[jmnunezd]

why is this different than a regular if/elif/else statement?

[deep.space.]

Looks confusing af. Why use bitwise or '|' instead of 'or', and underscore '_' for 'default' when it is typically a variable for unused parameters?

[DotaMobaUnionRu]

Without recursive algebraic data types pattern matching is not that powerfull.

[yash]

8:45 anyone up for writing a tail-call recursive version of this 😋?

[ssds]

To complicated structures, I don't want something like this in my production code. Python was slow but simple, now it became slow and complicated like scala, there should be some differences on market elsewhere what is the reason to choose Python?