1 files changed, 38 insertions, 0 deletions
diff --git a/hw05_arith_scanner.scm b/hw05_arith_scanner.scm
new file mode 100644
index 0000000..f15833f
--- /dev/null
+++ b/hw05_arith_scanner.scm
@@ -0,0 +1,38 @@
+#lang eopl
+
+;; <arith-expr> ::== <arith-term> { <add-op> <arith-term> }*
+;; <arith-term> ::== <arith-factor> { <mult-op> <arith-factor> }*
+;; <arith-factor> ::== <number>
+;; <arith-factor> ::== ( <arith-expr> )
+;; <add-op> ::== + | -
+;; <mult-op> ::== * | / 
+
+(define arith-scanner
+  '(
+    (add-op (or "+" "-") symbol)
+    (mult-op (or "*" "/") symbol)
+    (number (digit (arbno digit)) number)
+  ))
+
+(define arith-grammar
+  '(
+    (expression (number) arith-factor)
+    ;(expression (number add-op number) arith-factor)
+    ;(expression (expression add-op expression) arith-factor)
+    ))
+
+(sllgen:make-define-datatypes arith-scanner arith-grammar)
+
+(define list-the-datatypes
+  (lambda ()
+    (sllgen:list-define-datatypes arith-scanner arith-grammar)))
+
+(define just-scan
+  (sllgen:make-string-scanner arith-scanner '()))
+
+(define scan&parse
+  (sllgen:make-string-parser arith-scanner arith-grammar) )
+
+(define read-eval-print
+  (sllgen:make-rep-loop "--> " stmt-evaluator
+                        (sllgen:make-stream-parser arith-scanner arith-grammar) ))
+\ No newline at end of file