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null? and pair?
Learn null? and pair? in Scheme with a construct-specific explanation, unique example, engineering boundary, and mastery check.
null? and pair? is a focused Scheme topic inside Core Syntax. 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 null? and pair?, then change one input and predict the result before running it.
Topic-specific example
(list (null? '()) (pair? '(1 2)))
null? and pair? 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.