Struggling with trivial command line program

Questions & Answers
2

As I mentioned in another post, you do not need to use cli. Here’s the simplest variant:

#lang racket/base

(displayln (expt (string->number (vector-ref (current-command-line-arguments) 0)) 2))

;; $ racket file.rkt 8
;; 64

If you want to handle command-line parsing in a more principled way, you can use racket/cmdline.

#lang racket/base

(require racket/cmdline)

(define n
  (command-line
   #:args (number)
   (string->number number)))

(displayln (expt n 2))

;; $ racket file.rkt 8
;; 64
;; $ racket file.rkt
;; file.rkt: expects 1 <number> on the command line, given 0 arguments
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