scheme - If I shadow a buit-in function, how can I recover it? -

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take example:

(define sqrt (lambda (x) (* 2 (sqrt x)))) (sqrt 2) 2.828427 ...

how can call original built-in sqrt procedure without restarting interpreter (or undefine shadowing define)?

actually, happens internally when this? built-in overwritten, or 2 procedures coexist in different namespaces?

your definition of sqrt cause stack overflow, because recurses itself, not built-in sqrt. :-p

anyway, in racket, definition of sqrt affect current module only. possible reimport built-in sqrt under different name, , call module-specific sqrt:

(require (rename-in racket/base [sqrt racket-sqrt])) (define sqrt (lambda (x) (* 2 (racket-sqrt x))))

note code won't affect other modules don't import module's sqrt definition; continue use built-in sqrt.


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