refinement

beautiful-racket-demo/scriptish-demo/expander.rkt

@@ -1,8 +1,7 @@
 #lang br
 (require racket/stxparam)
 (provide (all-defined-out)
-         #%top-interaction #%top #%app
-         (rename-out [my-datum #%datum]))
+         #%app #%top #%datum #%top-interaction)
 
 (define-macro top #'#%module-begin)
 
@@ -18,20 +17,19 @@
   [(_ VAL) #'VAL]
   [(_ L "&&" R) #'(and L R)])
 
-(define-macro (my-datum . VAL)
-  (with-syntax ([NEW-VAL (let ([val (syntax->datum #'VAL)])
-                           (cond
-                             [(and (integer? val) (inexact? val))
-                              (inexact->exact val)]
-                             [(boolean? val) (if val "True" "False")]
-                             [else val]))])
-    #'(#%datum . NEW-VAL)))
+(define-macro (my-app ID ARG ...)
+  #'(error 'boom))
 
-(define-macro (var ID VAL) #'(define ID VAL))
+(define-macro-cases var
+  [(_ ID VAL) #'(define ID VAL)]
+  [(_ ID ... VAL) #'(begin (define ID VAL) ...)])
 
 (define (add/concat . xs)
   (cond
-    [(andmap number? xs) (apply + xs)]
+    [(andmap number? xs) (let ([sum (apply + xs)])
+                           (if (and (integer? sum) (inexact? sum))
+                               (inexact->exact sum)
+                               sum))]
     [(ormap string? xs) (string-join (map ~a xs) "")]))
   
 (define-macro-cases add-or-sub

beautiful-racket-demo/scriptish-demo/grammar.rkt

@@ -2,7 +2,7 @@
 
 top : @statement*
 statement : (var | expr | return | defun) /";" | if-else | while
-var : /"var" varname /"=" expr
+var : /"var" (varname /"=")+ expr
 @expr : reassignment
 reassignment : ID [("+=" | "-=") expr] | ternary
 ternary : expr /"?" expr /":" expr | logical-or

beautiful-racket-demo/scriptish-demo/main.rkt

@@ -4,7 +4,7 @@
 (module+ reader
   (provide read-syntax))
 
-(define-lex-abbrev reserved-terms
+(define-lex-abbrev reserved-toks
   (:or "var" "=" ";" "{" "}" "//" "/*" "*/"
        "+" "*" "/" "-"
        "'" "\""
@@ -20,14 +20,14 @@
   (lexer-srcloc
    [(:or (from/stop-before "//" "\n")
          (from/to "/*" "*/")) (token 'COMMENT #:skip? #t)]
-   [reserved-terms lexeme]
-   [(:+ (:- (:or alphabetic punctuation) "." reserved-terms))
-    (token 'ID (string->symbol lexeme))]
-   [(:+ (:- (:or alphabetic punctuation) reserved-terms))
-    (token 'DEREF (map string->symbol (string-split lexeme ".")))]
+   [reserved-toks lexeme]
    [(:seq (:? "-") (:or (:seq (:? digits) "." digits)
                         (:seq digits (:? "."))))
     (token 'NUMBER (string->number lexeme))]
+   [(:seq (:+ (:- (:or alphabetic punctuation digits) reserved-toks)))
+    (if (string-contains? lexeme ".")
+        (token 'DEREF (map string->symbol (string-split lexeme ".")))
+        (token 'ID (string->symbol lexeme)))]
    [(:or (from/to "\"" "\"") (from/to "'" "'"))
     (token 'STRING (string-trim lexeme (substring lexeme 0 1)))]
    [whitespace (token 'WHITE #:skip? #t)]