laike9m / python-type-challenges

Master Python typing (type hints) with interactive online exercises!

Python Type Challenges

Master Python typing (type hints) with interactive online exercises!

Click 👉👉 HERE to start

Happy typing!

How to Run Locally

You can also run the challenge locally. To do that, clone the project and install necessary dependencies, using either PDM or requirements.txt.

PDM is recommended. After installing PDM, you can install needed dependencies with the following steps:

pdm install
pdm dev  # This will run a local Flask server

Alternatively, you can install dependencies with requirements.txt:

pip install -r requirements.txt
flask run

How to Contribute

• Add new challenges

  Adding a new challenge is pretty simple: you only need to create a new folder, add a question.py and a solution.py, and that's it. See here for a detailed guidance.

• New features & bug fixes

  If you want to fix a bug or add a new feature, follow the guidance.

Got Questions?

For general questions, you can post them in Discussions.

If you met issues or want to suggest a new feature/improvement, feel free to open a new issue.

Sponsor

Credits

This project is inspired Type Exercise in Rust by @skyzh, and type-challenges by @antfu.

Social graph images come from Christin Hume.

python-type-challenges's Issues

The first run after each new Zeabur deployment is always quite slow (takes 10+ secs)

It seems pretty reproducible, but I'm not sure if this is our problem or theirs

Two challenges can't pass under mypy (and maybe more)

https://github.com/RF-Tar-Railt/Python-Type-Challenges/blob/main/challenges/advanced-overload-generic/question.py

https://github.com/RF-Tar-Railt/Python-Type-Challenges/blob/main/challenges/extreme-constructor-parameter/question.py

mypy

pyright only reports errors in test code, which is what we expected

This issue should be fixed once we migrate to pyright (#9)

cc @RF-Tar-Railt @frostming

The ellipsis in the function parameters of challenge intermediate/literalstring causes challenge failed

In challenge intermediate/literalstring, function execute_query has a parament accepted Iterable[str]，and set default value .... The same pattern is observed in the provided solution.

def execute_query(sql, parameters: Iterable[str] = ...):
    """No need to implement it"""

This will cause a type check error by pyright

error: Expression of type "ellipsis" cannot be assigned to parameter of type "Iterable[str]"

It seems like I must access type check by changing Iterable[str] to Iterable[str] | EllipsisType , like

from typing import Iterable, LiteralString
from types import EllipsisType


def execute_query(sql: LiteralString, parameters: Iterable[str] | EllipsisType = ...):
    """No need to implement it"""

or change ... to () for type check.

from typing import Iterable, LiteralString
from types import EllipsisType


def execute_query(sql: LiteralString, parameters: Iterable[str] = ()):
    """No need to implement it"""

I don't think either of the above solutions to be the best way for this issue, but I don't know any better way to use ellipsis for default parameter with type hint.

Show challenges in 4 columns on homepage

something like

basic       intermediate      advanced     extreme
basic-1    intermediate-1    advanced-1   extreme-1
basic-2    intermediate-2    advanced-2   extreme-2
   ...

Right now it's a single column, which doesn't look good

For implementation, we won't be reusing the whole challenge_list component, but we perhaps can make a component to represent challenges belonging to a single level, and reuse it.

Add newline in `typealias` challenge

The following fails to work on the typealias challenge:

"""
TODO:

Create a new type called Vector, which is a list of float.
"""

type Vector = list[float]

with the error:

Error:
7:error: Statements must be separated by newlines or semicolons

This took me a second, and the solution that's accepted is in fact:

"""
TODO:

Create a new type called Vector, which is a list of float.
"""

type Vector = list[float]
 

Note the trailing newline (I had to add a space as well because the GH markdown parser seems to swallow it otherwise).
I haven't looked at the code, but I suspect it's concatenating the left and right code samples without adding a newline, so this could come as a surprise to some.

It would in general maybe be better to just strip both the LHS and the RHS of any trailing whitespace, and concatenate them with a newline in the middle, just to avoid issues with indentation and newlines.

Challenge should include Python target version

Python version will affect the challenge test, such as:

Challenge - dict

type custom = dict[str, str]

def foo(x: custom):
    pass

it's ok in python 3.12, but could not pass the test.

Feature request: allow resetting user code to its original form

Scenario:
I write some codes, it does not work so I want to start over again. I want to remove all my code quickly and start from the original codes.

Feature: provide python version switch

pyright supports switch python version with command line option --pythonversion

Make sure `question.py` doesn't type check

Show type checker info on UI

@100gle How did you get the Python svg logo? I assume you used https://icon-sets.iconify.design/logos/python/ ?

Provide solutions to existing challenges

Example

https://github.com/laike9m/Python-Type-Challenges/blob/main/challenges/advanced-overload-literal/solution.py

Switch to use pyright

[Formatter] Replace `black`

Description

In black 24.1.0, many challenges will be formatted by black

Dummy class and function implementations consisting only of ... are formatted more
compactly

class Undergraduate:
    ...

It will be replaced with

class Undergraduate: ...

In solution.py, user should complete ...

class Undergraduate(Student):
    major: str

Suggestion

Replace black with ruff

Add `from typing import *` to boilerplate

I imagine that imports were left out to avoid giving clues, but it would be nice to have all the type hints imported into the namespace.

[Web] 500 Internal Server Error

Description

When I click the button online, the server return a 500 error.

---

However, I can run locally, it seems not error for python.
Or 84551ad cause?

Create a challenge for PEP 675: `LiteralString`

PEP 675

Add test to cover the end-to-end flow

Test should cover returning challenges from backend, and sending user code to backend and get type check result

[Bug] Old CodeMirrors are not remove

history-bug.mp4

这会提供参考答案吗？到了高级后期的时候，就不怎么会写了

Create a challenge for PEP 692: `Unpack[TypedDict]` for `**kwargs`

PEP 692

Consider adding a hint message with links for each question

Currently, there is no hint message for most questions. For a few questions like callable-protocol, there is a short "HINT: Use Protocol" written in the code, but there is no standard.

We do provide a "Solution" button, but it's very different from a hint. When the user is playing with each challenge, a well-designed hint message can guide him and help him complete the question by learning, but the "solution" button takes him directly to the answer--It's faster but the user may not learn anything at all!

So I'm suggesting that we add a hint message to all questions. The hint messages follow a standard format, like this:

• For basic/any: HINT: Check out Any.
• For intermediate/callable: HINT: Check out Callable.
• For intermediate/generic2: HINT: Check out TypeVar, constraints are needed for this question.
• ...

Implementation

The hint can be added directly in any question.py like this:

## HINT start ##
(message in Markdown format)
## HINT end ##

The server can extracts the message and render it as HTML(to make hyper link works).

Return type for extreme concatenate

In your solution to the extreme concatenate problem you propose:

def transform[T, **P](f: Callable[Concatenate[Any, P], T]):
    def wrapper(value: Person, *args: P.args, **kwargs: P.kwargs) -> T:
        return f(value, *args, **kwargs)

    return wrapper

But if I add the return type of Callable[Concatenate[Person, P], T] to the transform function, the test in line 19 fails.

Is there a better return type or do you recommend skipping it in general?

Define the criterias for determing a challenge's level

Right now there are 4 levels

• basic
• intermediate
• advanced
• extreme

Though there's no predefined criterias for determing a challenge's level.

Line numbers mismatch

Example:

It is a bit difficult to locate which line is incorrect.

Maybe we can split the challenge into source code part and test part.

much simpler solution to `extreme-self-casting`

this one felt a bit too easy -- I'm not sure how to change the problem to ...

spoilers

... require annotating [sic] `self`

from typing import *


class Fn[R, **P]:
    def __init__(self, f: Callable[P, R]):
        self.f = f

    def transform_callable(self) -> Callable[Concatenate[object, P], R]:
        ...

Allow custom challenge order

Currently the challenges appear in alphabetical order, it would be better if we customize the order by prioritizing the easier challenges to the top. For example, the basic challenges could use this order:

# The basic syntax
- parameter
- return
- variable
- any
- kwargs
# Composite data types
- list
- dict
- tuple
# Other
- typealias
- union
- optional
- final

This would make the experience better as people go through the challenges from top to bottom.

TypeAlias is marked as deprecated since 3.12 in docs

solution.py in recursive uses TypeAlias which is deprecated since 3.12.

On mobile devices, click elsewhere on the screen should fold the challenge list

Currently, they have to click the x button which is annoying an counterintuitive

[CI] Fail when pre-commit run

I think it related with #92

The example in `docs/Contribute.md` may be a little wrong

dict[str: str] does not seem to be correct, and it should be dict[str, str].

Create a challenge for PEP 696 (defaults for type variables)

PEP 696 defaults for type variables

Create a challenge for PEP 646: variadic generics and `TypeVarTuple`

PEP 646

Record and show passed challenges

It would be nice to show the status of each challenges (passed, not passed), like Leetcode:

We can store the information in localStorage

Create a challenge for PEP 698 `@override`

PEP 698

Too easy to pass `extreme-variance`

Description

def f(a: list[int | str]):
    pass


def g(a: str | list):
    pass

Suggestion

Maybe we can use definition to make challenge strict.

Optimize server memory usage

Zeabur free plan has a memory limit of 512MB, and it appears that we're running on the edge and (according to their dev team) have OOM'ed

[Web] Use HTMX to random page.

Description

Currently, click random button will reload the page, and all passed-icon will reload.

extreme-concatenate not working? (maybe outdated pyright)

this works locally -- and on the version of pyright stated in requirements.txt

spoilers

from typing import Protocol


class Person:
    pass


class P1[R, **P](Protocol):
    def __call__(self, value: object, *args: P.args, **kwargs: P.kwargs) -> R: ...

class P2[R, **P](Protocol):
    def __call__(self, value: Person, *args: P.args, **kwargs: P.kwargs) -> R: ...

def transform[R, **P](f: P1[R, P]) -> P2[R, P]:
    def wrapper(value: Person, *args: P.args, **kwargs: P.kwargs) -> R:
        return f(value, *args, **kwargs)

    return wrapper

peeked at the stated solution and it feels a little cheeky to rely on the type checker to fill in the return value there

Errors in running "Challenge - concatenate"

Hello,
I was trying to solve the last challenge.
this one

but I was getting strange errors in the output, so
I decided to test out the real solution but again, pasting & running the solution produced errors:

[Bug] Pass challenges with `raise`

Bug description

If # expect-type-error not in test_code, challenge can pass with raise.

Challenges

• advanced-forward
• advanced-never2

Enable UTF-8 mode for python (PEP 686)

Description

After pdm dev, UnicodeDecodeError(gbk: illegal multibyte sequence) caused by string ——

the string is in Python-Type-Challenges/challenges/intermediate-self/hints.md

---

Also, the emoji cannot load successfully

Solution

Python UTF-8 mode

[Docs] Add random challenge entrance to README

As we have random challenge entrance, we can add it to README.

We need explicitly specify the Python version in context

It is also necessary to explicitly specify the Python version in the context, otherwise a lot of the solving will be affected.

Create a Logo

Image size should be 1200 x 630 to fit the requirement of social networks

Add a test to verify the test code in question and solution are identical

In case people accidentally changed on but forget about the other