Lesson 15 of 55
9 mins readAnonymous Lambda Expressions (\x -> expr)
In Plain English
Anonymous functions (lambdas) are written with a backslash \ (resembling the Greek letter λ) followed by parameter names and an arrow ->.
Deep Dive: How It Works
Lambda Syntax: \x -> x * 2 is an anonymous function taking x and returning x * 2.
Multi-Parameter Lambdas: \x y -> x + y takes two parameters.
Inline Callbacks: Ideal for one-off callbacks in map, filter, and fold operations.
Core Rules to Remember
Backslash \ Notation: Represents lambda λ in plain ASCII text.
One-Off Transformations: Avoid defining named top-level functions for trivial transformations.
Live Interactive Example
Hit Run Code to see it liveLambdas in Higher-Order Functions
Python 3.12
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Output Console
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How it works: \x -> x^2 maps over numbers. zipWith applies \a b -> a + b*10 to pairs.
Your Turn: Micro Challenge
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Micro Exercise
Filter Elements with Lambda
- Use `filter (\x -> x > 15) [10, 20, 5, 25, 30]` and print the result.
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Sandbox Output
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