MAPHASH

; Changes each entry in THE-HASH-TABLE,

; replacing each positive value with its

; square root, and removing negative values.

(maphash ; Steele’84, p285.

#'(lambda (key value)

(if (minusp value)

(remhash key the-hash-table)

(setf (gethash key the-hash-table)

(sqrt value))))

the-hash-table)

; returns NIL

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