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This module contains some easy looping macros. They are implemented in the Design by Contract style, i.e. using the contracts module. A corollary of this is, that the documentation is included in the module. By convention, there is a routine with the module's name, loops, which when called with no argument
returns the list of exported symbols, namely
(do-for do-forever do-list do-times do-until do-while)
which are all macros, while calling loops with one of this symbols, e.g.
shows the documentation of this symbol in all it's glory, i.e. together with admissible forms and documentation
(forms: (do-list i lst xpr xpr1 ...)) "do xpr ... for i in a list lst"
Another way to get the complete documentation is to use print-doclist from the contracts module. Issuing
(import loops (only contracts print-doclist)) (with-output-to-file "loops.docu" (lambda () (print-doclist)))
you'll get the complete documentation written to the file loops.docu, which looks as follows:
do-for ------ (forms: (do-for var (start stop step) xpr xpr1 ...) (do-for var (start stop) xpr . xprs)) "do xpr ... for var in [start stop[ with steps (default 1)" do-forever ---------- (forms: (do-forever . body) "executes body until exit is called") do-list ------- (forms: (do-list i lst xpr xpr1 ...)) "do xpr ... for i in a list lst" do-times -------- (forms: (do-times i upto xpr0 xpr1 ...)) "do xpr ... for i in [0 upto[" do-until -------- (forms: (do-until test? xpr xpr1 ...)) "do xpr ... while test? is false" do-while -------- (forms: (do-while test? xpr xpr1 ...)) "do xpr ... while test? is true"
(import loops) (let ((lst '())) (do-times i (+ 2 3) (set! lst (cons i lst))) lst) ; -> '(4 3 2 1 0) (let ((lst '())) (do-list i '(1 2 3) (set! lst (cons i lst))) lst) ; -> '(3 2 1) (let ((lst '())) (do-for i (1 5) (set! lst (cons i lst))) (reverse lst)) ; -> '(1 2 3 4) (let ((lst '())) (do-for i (1 65 i) (set! lst (cons i lst))) (reverse lst)) ; -> '(1 2 4 8 16 32 64) (let ((n 4) (lst '())) (do-while (<= 0 n) (set! lst (cons n lst)) (set! n (- n 1))) lst) ; -> '(0 1 2 3 4) (let ((n 4) (lst '())) (do-until (> 0 n) (set! lst (cons n lst)) (set! n (- n 1))) lst) ; -> '(0 1 2 3 4) (let ((n 3) (lst '())) (do-forever (if (zero? n) (exit lst)) (set! lst (cons 'a lst)) (set! n (- n 1)))) ; -> '(a a a)
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- initial import