diff options
| -rw-r--r-- | racket.html.markdown | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/racket.html.markdown b/racket.html.markdown index fbd3f76a..90b29d21 100644 --- a/racket.html.markdown +++ b/racket.html.markdown @@ -365,13 +365,16 @@ n ; => 6 (set-box! n* (add1 (unbox n*))) (unbox n*) ; => 6 -;; Many Racket datatypes can be immutable or mutable -;; (Pairs, Lists, Strings, Vectors, Hash Tables, etc...) +;; Many Racket datatypes are immutable (pairs, lists, etc), some come in +;; both mutable and immutable flavors (strings, vectors, hash tables, +;; etc...) -;; Use `vector' to create a mutable vector +;; Use `vector' or `make-vector' to create mutable vectors (define vec (vector 2 2 3 4)) +(define wall (make-vector 100 'bottle-of-beer)) ;; Use vector-set! to update a slot (vector-set! vec 0 1) +(vector-set! wall 99 'down) vec ; => #(1 2 3 4) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; |