Lesson 33 of 55
9 mins readPython Pattern Matching on Maybe & Either
In Plain English
Learn idiomatic ways to extract wrapped values from Maybe and Either using pattern matching, case expressions, and the catMaybes utility.
Deep Dive: How It Works
Pattern Matching Maybe: handle (Just x) = process x; handle Nothing = fallback.
catMaybes: Filters a list [Maybe a] -> [a], dropping all Nothing elements and keeping only unwrapped Just values.
isJust & isNothing: Boolean query functions in Data.Maybe.
Core Rules to Remember
Exhaustive Unpacking: Pattern matching guarantees all potential failure cases are covered.
catMaybes Filtering: Extract valid values from a collection of optional results cleanly.
Live Interactive Example
Hit Run Code to see it liveFiltering and Processing Maybe Collections
Python 3.12
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Output Console
Click "Run Code" to view the rendered output.
How it works: catMaybes stripped all Nothing elements safely.
Your Turn: Micro Challenge
No pressure! Edit the starter code below and test your solution with instant feedback.
Micro Exercise
Extract with fromMaybe
- Use `fromMaybe 100 (Just 50)` and assign to `val`.
- Print `"Extracted: "` followed by `show val`.
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Sandbox Output
Click "Run & Check" to test your solution.
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