Types-First (Typing Stubs for 'first' library)

2.0.5.20260408 · active · verified Fri Apr 17

This package provides PEP 561 compatible type stubs for the `first` library. It enables static type checkers like MyPy to correctly analyze code that uses the `first` function, enhancing code quality and preventing type-related errors. The current version is 2.0.5.20260408, and it's released as part of the `typeshed` project, which updates periodically.

Common errors

```
error: Missing type stubs for "first"
```
cause MyPy or another static type checker cannot find the type definitions for the 'first' library.

fix Install the type stub package: `pip install types-first`.
```
ModuleNotFoundError: No module named 'first'
```
cause The actual 'first' runtime library is not installed in your Python environment. `types-first` only provides type hints, not the executable code.

fix Install the runtime library: `pip install first`.
```
error: Module "first" has no attribute "first" (MyPy error)
```
cause This usually indicates a conflict, a corrupted installation, or a version mismatch where MyPy cannot correctly interpret the 'first' module's structure, even with stubs installed.

fix Ensure both `first` and `types-first` are up-to-date and compatible. Try reinstalling both: `pip uninstall first types-first && pip install first types-first`. Check MyPy configuration for any exclusions or incorrect paths.

Warnings

gotcha Installing `types-first` only provides static type information; it does not include the actual `first` runtime library. Your application will encounter a `ModuleNotFoundError` if `first` is used in code without `pip install first`.
Fix: Always install both `first` and `types-first`: `pip install first types-first`.
gotcha Type stub versions can sometimes lag behind or become out of sync with the runtime library versions. This might lead to incorrect type checking or false positives/negatives from static analysis tools if the API of `first` changes without corresponding stub updates.
Fix: Ensure both `first` and `types-first` are updated regularly. If encountering type errors, check the `typeshed` GitHub repository for the latest status or specific issues related to `first` stubs.
gotcha For stub packages, direct imports like `import types_first` are not used. The `types-first` package simply needs to be installed in the environment for type checkers to find it when processing imports of the `first` library.
Fix: Do not attempt to import `types_first`. Continue to import the actual runtime library: `from first import first`.

Install

pip install types-first Install type stubs
pip install first Install runtime library (required)

Imports

first
```
from first import first
```
This stub package provides type hints for the `first` function from the `first` library. You do not directly import `types-first` in your code; its presence is detected by type checkers.

Quickstart

This quickstart demonstrates how to use the `first` function with type hints. Installing `types-first` allows static analysis tools like MyPy to verify the types, such as ensuring `get_first_even` correctly handles `Optional[int]`.

from typing import List, Optional
from first import first

def get_first_even(numbers: List[int]) -> Optional[int]:
    """Finds the first even number in a list using the 'first' library."""
    # MyPy will use types-first to understand 'first' returns Optional[int]
    return first(numbers, key=lambda x: x % 2 == 0)

# Example usage with type hints
data: List[int] = [1, 3, 4, 5, 6]
result: Optional[int] = get_first_even(data)
print(f"First even number: {result}") # Expected: 4

data_no_even: List[int] = [1, 3, 5]
result_no_even: Optional[int] = get_first_even(data_no_even)
print(f"First even number (none found): {result_no_even}") # Expected: None

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