commit 27fc80861aab7e7ba9eea88e3fb3cb309c9c3a2c
parent 2af1256427b78ae8520979866a0fbea6df0d3d6d
Author: Greg Hendershott <greghendershott@gmail.com>
Date: Tue, 21 Apr 2015 14:31:13 -0400
Fix hash.refs example. Fixes #15.
Diffstat:
| M | index.rkt | | | 42 | +++++++++++++++++++----------------------- |
1 file changed, 19 insertions(+), 23 deletions(-)
diff --git a/index.rkt b/index.rkt
@@ -1177,17 +1177,16 @@ like JavaScript?
(require (for-syntax racket/syntax))
(define-syntax (hash.refs stx)
(syntax-case stx ()
- ;; If the optional `default' is missing, assume it's #f.
+ ;; If the optional `default' is missing, use #f.
[(_ chain)
#'(hash.refs chain #f)]
[(_ chain default)
- (let ([xs (map (lambda (x)
- (datum->syntax stx (string->symbol x)))
- (regexp-split #rx"\\."
- (symbol->string (syntax->datum #'chain))))])
- (with-syntax ([h (car xs)]
- [ks (cdr xs)])
- #'(hash-refs h 'ks default)))]))
+ (let* ([chain-str (symbol->string (syntax->datum #'chain))]
+ [ids (for/list ([str (in-list (regexp-split #rx"\\." chain-str))])
+ (format-id #'chain "~a" str))])
+ (with-syntax ([hash-table (car ids)]
+ [keys (cdr ids)])
+ #'(hash-refs hash-table 'keys default)))]))
;; Gives us "sugar" to say this:
(hash.refs js.a.b.c)
;; Try finding a key that doesn't exist:
@@ -1208,26 +1207,23 @@ messages when used in error. Let's try to do that here.
(syntax-case stx ()
;; Check for no args at all
[(_)
- (raise-syntax-error #f "Expected (hash.key0[.key1 ...] [default])"
- stx #'chain)]
+ (raise-syntax-error #f "Expected hash.key0[.key1 ...] [default]" stx #'chain)]
+ ;; If the optional `default' is missing, use #f.
[(_ chain)
#'(hash.refs chain #f)]
[(_ chain default)
- ;; Check that chain is a symbol, not e.g. a number or string
- (unless (symbol? (syntax-e #'chain))
- (raise-syntax-error #f "Expected (hash.key0[.key1 ...] [default])"
- stx #'chain))
- (let ([xs (map (lambda (x)
- (datum->syntax stx (string->symbol x)))
- (regexp-split #rx"\\."
- (symbol->string (syntax->datum #'chain))))])
+ (raise-syntax-error #f "Expected hash.key0[.key1 ...] [default]" stx #'chain)
+ (let* ([chain-str (symbol->string (syntax->datum #'chain))]
+ [ids (for/list ([str (in-list (regexp-split #rx"\\." chain-str))])
+ (format-id #'chain "~a" str))])
;; Check that we have at least hash.key
- (unless (and (>= (length xs) 2)
- (not (eq? (syntax-e (cadr xs)) '||)))
+ (unless (and (>= (length ids) 2)
+ (not (eq? (syntax-e (cadr ids)) '||)))
(raise-syntax-error #f "Expected hash.key" stx #'chain))
- (with-syntax ([h (car xs)]
- [ks (cdr xs)])
- #'(hash-refs h 'ks default)))]))
+ (with-syntax ([hash-table (car ids)]
+ [keys (cdr ids)])
+ #'(hash-refs hash-table 'keys default)))]))
+
;; See if we catch each of the misuses
(hash.refs)
(hash.refs 0)
