tweakage

coerce.rkt

@@ -5,7 +5,7 @@
 
 
 (define (make-coercion-error-handler target-format x)
-  (λ(e) (error (format "Can't convert ~a to ~a" x target-format))))
+  (λ(e) (error (format "Can’t convert ~a to ~a" x target-format))))
 
 ;; general way of coercing to integer
 (define+provide/contract (->int x)

container.rkt

@@ -56,12 +56,12 @@
 ;; put item as first arg so function can use infix notation
 ;; (item . in . container)
 (define/contract (in? item container)
-  (any/c any/c . -> . boolean?)
-  (->boolean (cond
-               [(list? container) (member item container)] ; returns #f or sublist beginning with item
-               [(vector? container) (vector-member item container)] ; returns #f or zero-based item index
-               [(hash? container) 
-                (and (hash-has-key? container item) (get container item))] ; returns #f or hash value
-               [(string? container) ((->string item) . in? . (map ->string (string->list container)))] ; returns #f or substring beginning with item
-               [(symbol? container) ((->string item) . in? . (->string container))] ; returns #f or subsymbol (?!) beginning with item
-               [else #f])))
+  (any/c any/c . -> . coerce/boolean?)
+  (cond
+    [(list? container) (member item container)] ; returns #f or sublist beginning with item
+    [(vector? container) (vector-member item container)] ; returns #f or zero-based item index
+    [(hash? container) 
+     (and (hash-has-key? container item) (get container item))] ; returns #f or hash value
+    [(string? container) (regexp-match (->string item) (->string container))] ; returns #f or substring beginning with item
+    [(symbol? container) ((->string item) . in? . (->string container))] ; returns #f or subsymbol (?!) beginning with item
+    [else #f]))

define.rkt

@@ -4,6 +4,9 @@
 
 (provide define+provide define+provide/contract define/contract+provide)
 
+;; each define macro recursively converts any form of define
+;; into its lambda form (define name body ...) and then operates on that.
+
 (define-syntax (define+provide stx)
   (syntax-case stx ()
     [(_ (proc arg ... . rest-arg) body ...)
@@ -14,6 +17,7 @@
          (provide name)
          (define name body ...))]))
 
+
 (define-syntax (define+provide/contract stx)
   (syntax-case stx ()
     [(_ (proc arg ... . rest-arg) contract body ...)
@@ -25,7 +29,6 @@
          (define name body ...))]))
 
 
-
 (define-syntax (define/contract+provide stx)
   (syntax-case stx ()
     [(_ (proc arg ... . rest-arg) contract body ...)