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contract-out
Learn contract-out in Racket with a construct-specific explanation, unique example, engineering boundary, and mastery check.
contract-out is a focused Racket topic inside Contracts and Modules. This lesson explains the construct itself, the state or value it operates on, and the observable result it produces.
Read the example as a small executable experiment. Identify the exact syntax that belongs to contract-out, then change one input and predict the result before running it.
Topic-specific example
(provide (contract-out [double (-> number? number?)]))
(define (double x) (* 2 x))
contract-out has rules that are easy to miss when the example is copied mechanically. Check the feature-specific boundary shown by this construct: scope, mutability, evaluation order, type constraints, lifetime, error behavior, compile-time restrictions, or resource cleanup where applicable.