An execution environment for functional code may treat application segments as individual programs for memory management. A larger program of application may be segmented into functional blocks that receive an input and return a value, but operate without changing state of other memory objects. The program segments may have memory pages allocated to the segments by the operating system as other full programs, and may deallocate memory pages when the segments finish operating. Functional programming languages and imperative programming languages may define program segments explicitly or implicitly, and the program segments may be identified at compile time or runtime.