Workshop: Type Hints (Optional, Self-Study)¶

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From the lesson

Workshop problems for Section 08 Concepts. Build each yourself first, then expand the solution to check.

Three optional workshop problems, one per concept step, in a car scenario. Self-study: check python-workshop/solutions.

Step-01: Function Parameter and Return Hints¶

Concepts: parameter and return type hints.

Write a function label that takes a car brand and a year and returns the text "<brand> (<year>)", with type hints saying it takes a str and an int and returns a str. Call it with "Mazda" and 2020 and print the result.

Expected output

Mazda (2020)

Need a hint?

Mix the hint types on one def line: def label(brand: str, year: int) -> str:, then return an f-string like f"{brand} ({year})".

Show the solution

s08_workshop01_sol_function_hints.py

def label(brand: str, year: int) -> str:
    return f"{brand} ({year})"
print(label("Mazda", 2020))

View the full solution file on GitHub

Pages for this step: Concept | Practice | Workshop

Python Files for this step: Concept | Practice | Practice Solutions | Workshop | Workshop Solutions

Step-02: Variable Hints and Container Hints¶

Concepts: list[int], dict[str, int].

Write a program that:

Task-1: define a variable mileages holding the list of whole numbers 12000, 8000, 15000, with a variable hint saying it is a list[int], then print the list and print the highest mileage.
Task-2: define a variable prices holding a mapping of car brand to whole-number price, with Mazda at 15000 and Tesla at 42000, and a variable hint saying it is a dict[str, int], then look up Tesla's price and print it.

Expected output

[12000, 8000, 15000]
15000
42000

Need a hint?

Hint each variable at definition: mileages: list[int] = [...] and prices: dict[str, int] = {...}. Use max(mileages) for the highest and prices["Tesla"] for the lookup.

Show the solution

s08_workshop02_sol_variable_and_container_hints.py

# Task-1: typed mileage list, print and highest
mileages: list[int] = [12000, 8000, 15000]
print(mileages)
print(max(mileages))
# Task-2: typed brand-to-price map, look up Tesla
prices: dict[str, int] = {"Mazda": 15000, "Tesla": 42000}
print(prices["Tesla"])

View the full solution file on GitHub

Pages for this step: Concept | Practice | Workshop

Python Files for this step: Concept | Practice | Practice Solutions | Workshop | Workshop Solutions

Step-03: Optional Values, and Hints Are Not Enforced¶

Concepts: int | None (optional), .get().

Write a function find_car_price that takes a car brand and looks it up in a price list (Mazda at 15000 and Tesla at 42000), returning the matching price or nothing when the brand is missing, with type hints saying it takes a str and returns either an int or None. Call it for "Mazda" (known) and "Kia" (unknown) and print each result.

Expected output

15000
None

Need a hint?

Use -> int | None so a missing brand can return None, and prices.get(brand) gives None instead of raising when "Kia" is not a key.

Show the solution

s08_workshop03_sol_optional_and_not_enforced.py

def find_car_price(brand: str) -> int | None:
    prices = {"Mazda": 15000, "Tesla": 42000}
    return prices.get(brand)
print(find_car_price("Mazda"))
print(find_car_price("Kia"))

View the full solution file on GitHub

Pages for this step: Concept | Practice | Workshop

Python Files for this step: Concept | Practice | Practice Solutions | Workshop | Workshop Solutions

Finished this section?

Check your work against the solutions above, then head back to the Section 08 lesson, or try the Section 08 practice for more reps.

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