ebus-racket: use define instead of let

1 files changed, 62 insertions, 61 deletions

diff --git a/ebus-racket/layer7.rkt b/ebus-racket/layer7.rkt
index 5cb4477..95739e6 100644
--- a/ebus-racket/layer7.rkt
+++ b/ebus-racket/layer7.rkt
@@ -10,11 +10,11 @@
 
 
 (define (paket ebus-paket)
-  (let ([primaryCommand (layer2-ebus-paket-primaryCommand ebus-paket)]
-        [secondaryCommand (layer2-ebus-paket-secondaryCommand ebus-paket)])
-    ((sxpath (string-append "//packet[@primary=" (number->string primaryCommand)
-                            " and @secondary=" (number->string secondaryCommand) "]"))
-     definition)))
+  (define primaryCommand (layer2-ebus-paket-primaryCommand ebus-paket))
+  (define secondaryCommand (layer2-ebus-paket-secondaryCommand ebus-paket))
+  ((sxpath (string-append "//packet[@primary=" (number->string primaryCommand)
+			  " and @secondary=" (number->string secondaryCommand) "]"))
+   definition))
 
 ;; returns the full device-definition
 (define (device address)
@@ -27,55 +27,55 @@
 
 
 (define (paket-fields ebus-paket)
-  (let ([paket-definition (paket ebus-paket)])
-    (cond ((> (length paket-definition) 0)
-	   (let* 
-	       ([paket-name (first ((sxpath "@name/text()") paket-definition))]
-		[fields ((sxpath "fields/*") paket-definition)]
-		[values 
-		 (for/list ([field fields]) (paket-fields-dispatch-decoder ebus-paket field paket-name))])
-	     ;; filter invalid values
-	     (for/list ([value values] #:when (not (void? value)))
-		       value)))
-	  (else (display (format "Unknown Paket: ~s~n" ebus-paket))
-		(void)))))
+  (define paket-definition (paket ebus-paket))
+  (cond ((> (length paket-definition) 0)
+	 (let* 
+	     ([paket-name (first ((sxpath "@name/text()") paket-definition))]
+	      [fields ((sxpath "fields/*") paket-definition)]
+	      [values 
+	       (for/list ([field fields]) (paket-fields-dispatch-decoder ebus-paket field paket-name))])
+	   ;; filter invalid values
+	   (for/list ([value values] #:when (not (void? value)))
+		     value)))
+	(else (display (format "Unknown Paket: ~s~n" ebus-paket))
+	      (void))))
 
 (define (paket-fields-dispatch-decoder ebus-paket field paket-name)
-  (let ([datatype ((sxpath "name()") field)]
-	[name (string-append paket-name "." (first ((sxpath "@name/text()") field)))]
-	[offset (string->number (first ((sxpath "@offset/text()") field)))]
-	[payload (layer2-ebus-paket-payload ebus-paket)])
-    (cond ((string=? "bit" datatype)
-	   (list name datatype offset
-		 (field-decoder-bit (list-ref payload offset))))
-	  ((string=? "bcd" datatype)
-	   (list name datatype offset
-		 (field-decoder-bcd (list-ref payload offset))))
-	  ((string=? "data1b" datatype)
-	   (list name datatype offset
-		 (field-decoder-data1b (list-ref payload offset))))
-	  ((string=? "data1c" datatype)
-	   (list name datatype offset
-		 (field-decoder-data1c (list-ref (layer2-ebus-paket-payload ebus-paket) offset))))
-	  ((string=? "byte" datatype)
-	   (list name datatype offset (list-ref payload offset)))
-	  ((string=? "data2b" datatype)
-	   (list name datatype offset
-		 (field-decoder-data2b (list-ref payload offset)
-				       (list-ref payload (+ offset 1)))))
-	  ((string=? "data2c" datatype)
-	   (list name datatype offset
-		 (field-decoder-data2c (list-ref payload offset)
-				       (list-ref payload (+ offset 1)))))
-	  ((string=? "word" datatype)
-	   (list name datatype offset
-		 (field-decoder-word (list-ref payload offset)
+  (define datatype ((sxpath "name()") field))
+  (define name (string-append paket-name "." (first ((sxpath "@name/text()") field))))
+  (define offset (string->number (first ((sxpath "@offset/text()") field))))
+  (define payload (layer2-ebus-paket-payload ebus-paket))
+  (cond ((string=? "bit" datatype)
+	 (list name datatype offset
+	       (field-decoder-bit (list-ref payload offset))))
+	((string=? "bcd" datatype)
+	 (list name datatype offset
+	       (field-decoder-bcd (list-ref payload offset))))
+	((string=? "data1b" datatype)
+	 (list name datatype offset
+	       (field-decoder-data1b (list-ref payload offset))))
+	((string=? "data1c" datatype)
+	 (list name datatype offset
+	       (field-decoder-data1c (list-ref (layer2-ebus-paket-payload ebus-paket) offset))))
+	((string=? "byte" datatype)
+	 (list name datatype offset (list-ref payload offset)))
+	((string=? "data2b" datatype)
+	 (list name datatype offset
+	       (field-decoder-data2b (list-ref payload offset)
+				     (list-ref payload (+ offset 1)))))
+	((string=? "data2c" datatype)
+	 (list name datatype offset
+	       (field-decoder-data2c (list-ref payload offset)
 				     (list-ref payload (+ offset 1)))))
-	  ((string=? "byteEnum" datatype)
-	   (list name datatype offset
-		 (field-decoder-byteEnum (list-ref payload offset) field)))
-	  (else (display (string-append "unknown datatype: " datatype "\n"))
-		(void)))))
+	((string=? "word" datatype)
+	 (list name datatype offset
+	       (field-decoder-word (list-ref payload offset)
+				   (list-ref payload (+ offset 1)))))
+	((string=? "byteEnum" datatype)
+	 (list name datatype offset
+	       (field-decoder-byteEnum (list-ref payload offset) field)))
+	(else (display (string-append "unknown datatype: " datatype "\n"))
+	      (void))))
 
 ;; type bit
 (define (field-decoder-bit value)
@@ -119,13 +119,13 @@
 (define (field-decoder-byteEnum value field-definition)
   (define (pred l)
     (= value (list-ref l 0)))
-  (let* ([all-options (for/list ([option ((sxpath "option") field-definition)])
+  (define all-options (for/list ([option ((sxpath "option") field-definition)])
 				(list (string->number (first ((sxpath "@value/text()") option))) ;; value, name
-				      (first ((sxpath "@name/text()") option))))]
-	 [options (filter pred all-options)])
-    (cond ((= (length options) 1)
-	   (list-ref (first options) 1))
-	  (else "<undefined>"))))
+				      (first ((sxpath "@name/text()") option)))))
+  (define options (filter pred all-options))
+  (cond ((= (length options) 1)
+	 (list-ref (first options) 1))
+	(else "<undefined>")))
 
 ;; type word
 (define (field-decoder-word lowByte highByte)
@@ -140,13 +140,14 @@
 ;; read one ebus-paket or eof from input-port
 ;; or return #<eof>
 (define (read-ebus input-port)
-  (let* ([paket (layer2-read-ebus input-port)])
-    (cond ((layer2-ebus-paket? paket)
-	   (paket-fields paket))
-	  (else paket))))
+  (define paket (layer2-read-ebus input-port))
+  (cond ((layer2-ebus-paket? paket)
+	 (paket-fields paket))
+	(else paket)))
 
 (provide (prefix-out layer7- paket)
          (prefix-out layer7- paket-fields)
          (prefix-out layer7- device)
          (prefix-out layer7- device-name)
+	 ;; read ebus from port an return fields from next paket
 	 (prefix-out layer7- read-ebus))
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