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3 points by sjs 2473 days ago | link | parent

Both nil and (len str) work. I see both sides of the argument as counting from -1 eliminates the 0 corner case.

I like indices that are intuitive with literal numbers. Counting from 0 at one end and from 1 at the other is jarring. When -1 points to the end of string rather than before the last char (cut str 0 (- (len str))) returns the first char instead of the empty string.

With -1 -> before last char:

  (def chop ((o str "abcdef"))
    (pr "Chop how many chars off the end of \"" str "\"? ")
    (= n (coerce (cut (readline) 1) 'int)) ; bug in readline prepends #\newline
    (prn "Chopped: \"" (if (is n 0) str (cut str 0 (- n))) "\"")) ; handle corner case
With -1 -> end of string:

  (def chop ((o str "abcdef"))
    (pr "Chop how many chars off the end of \"" str "\"? ")
    (= n (coerce (cut (readline) 1) 'int)) ; bug in readline prepends #\newline
    (prn "Chopped: \"" (cut str 0 (- -1 n)) "\"")) ; no corner case, but there's this -1 there
I probably made a stronger argument for -1 pointing to the end of string as it leads to shorter code.