case — Expert Playground

Defines a pattern branch inside a match statement (3.10+)

Python Playground

import dis

def match_types(x):
    match x:
        case int():
            return "int"
        case str():
            return "str"
        case _:
            return "other"

def match_sequence(x):
    match x:
        case [a, b]:
            return a + b
        case [a, b, c]:
            return a + b + c

print("Type matching:")
dis.dis(match_types)
print("\nSequence matching:")
dis.dis(match_sequence)

# Type patterns compile to isinstance() checks
# Sequence patterns check: is sequence? len matches? extract items
# The compiler generates optimized decision trees

Output

Click "Run" to execute your code

case patterns compile to isinstance checks (for type patterns), length checks + indexing (for sequences), and key lookups (for mappings). The compiler orders checks to fail fast.

Challenge

Try modifying the code above to explore different behaviors. Can you extend the example to handle a new use case?

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