procgen  Diff

Differences From Artifact [833aa00a5f]:

• File lib/struct.scm — part of check-in [6822b7d006] at 2019-03-30 03:45:34 on branch trunk — add libs (user: lexi, size: 2782) [annotate] [blame] [check-ins using]

To Artifact [06f94eb978]:

• File lib/struct.scm — part of check-in [294d779091] at 2019-04-17 23:45:48 on branch trunk — tidy up headers (user: lexi, size: 2883) [annotate] [blame] [check-ins using]

     1         -; ʞ / struct.scm
            1  +; [ʞ] struct.scm
            2  +;  ~ lexi hale <lexi@hale.su>
            3  +;  © affero general public license
            4  +;  > (load "lib/struct.scm")
     2      5   ;
     3      6   ; generates immutable, relatively efficient structs. declare
     4      7   ; a struct type x with
     5      8   ;	(define x (struct 'field1 'field2) 
     6      9   ; create a record y of that type with
     7     10   ;	(define y (x 123 456))
     8     11   ; access field1 of record y with
     9     12   ;	(y 'field1)
    10     13   ; update field2 of record y with
    11     14   ;	(y 'field2 123) → new record (field1 = 123; field2 = 123)
    12     15   ;
    13         -; this unit also includes a few utility function that chicken
    14         -; scheme conveniently "forgot." i apologize for the implementation
    15         -; of (list-head). i was very tired.
           16  +; this  unit also  includes a  few utility  function that
           17  +; chicken scheme  conveniently "forgot." i  apologize for
           18  +; the implementation of (list-head). i was very tired.
    16     19   
    17     20   ; return a sub-list of lst up to ct (inverse of list-tail)
    18     21   (define (list-head lst ct)
    19     22     (let* ([reverse-lst (reverse lst)]
    20     23   		 [idx (- (length lst) (+ 1 ct))])
    21     24   	(reverse (list-tail reverse-lst idx))))
    22     25   	; i'm not proud of this