Examples of recursion: string-merge

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Lecture 2 - Page 6 : 35

Programming Paradigms
Recursion and Higher-order Functions

Examples of recursion: string-merge

The function string-merge zips two lists of strings to a single string. The lists are not necessarily of equal lengths

(define (string-merge str-list-1 str-list-2)
 (cond ((null? str-list-1) (apply string-append str-list-2))
       ((null? str-list-2) (apply string-append str-list-1))
       (else (string-append
              (car str-list-1) (car str-list-2)
              (string-merge (cdr str-list-1) (cdr str-list-2))))))

The recursive function string-merge. Notice that this function is a general recursive function. The recursive call, emphasized above, is not in a tail position, because of the embedding in string-append.

A tail recursive version of string-merge.

More about string-merge