Introduce threading macro.

parse-map.scm

@@ -42,6 +42,14 @@
   (format #t "~{|~{~[ ~:;#~]~}|~%~}"
           (array->list tilemap)))
 
+(define-syntax ->
+  (syntax-rules ()
+    ((-> obj)
+     obj)
+    ((-> obj (func args ...) rest ...)
+     (-> (func obj args ...) rest ...))
+    ((-> obj func rest ...)
+     (-> (func obj) rest ...))))
 
 (define* (bytevector->c-string
           bv #:key (transcoder (make-transcoder "ASCII")))
@@ -170,9 +178,8 @@ else insert the value as given"
 (define (tile-list->tilemap tile-list)
   (let ((tilemap (make-array 0 64 64)))
     (for-each (lambda (tile coord)
-                (let ((tile (logand tile #xFF)))
-                  (when (< tile AREATILE)
-                    (apply array-set! tilemap tile coord))))
+                (when (< tile AREATILE)
+                  (apply array-set! tilemap tile coord)))
               tile-list
               (cross-product (iota 64) (iota 64)))
     tilemap))
@@ -197,18 +204,17 @@ else insert the value as given"
          (begin
            (seek port pos SEEK_SET)
            (make-maptype
-            (list-head        ; planestart
-             (u32vector->list
-              (get-bytevector-n port (* 3 4)))
-             MAPPLANES)
-            (list-head        ; planelength
-             (u16vector->list
-              (get-bytevector-n port (* 3 2)))
-             MAPPLANES)
-            (u16vector-ref (get-bytevector-n port 2) 0) ; width
-            (u16vector-ref (get-bytevector-n port 2) 0) ; height
-            (bytevector->c-string (get-bytevector-n port 16))
-
+            (-> port                    ; planestart
+                (get-bytevector-n (* 3 4))
+                u32vector->list
+                (list-head MAPPLANES))
+            (-> port                    ; planelength
+                (get-bytevector-n (* 3 2))
+                u16vector->list
+                (list-head MAPPLANES))
+            (-> port (get-bytevector-n  2) (u16vector-ref 0)) ; width
+            (-> port (get-bytevector-n  2) (u16vector-ref 0)) ; height
+            (-> port (get-bytevector-n 16) bytevector->c-string)  ; name
             ;; (bytevector->string (get-bytevector-n port  4) "ASCII") ; "!ID!"
             ))))
    (get-offsets maphead)))
@@ -218,12 +224,13 @@ else insert the value as given"
 (define (parse-map-data map-metadata port)
   (map (lambda (pos compressed)
          (seek port pos SEEK_SET)  ; ID_CA.C, 1454
-         (let* ((len (u16vector-ref (get-bytevector-n port 2) 0))
-                (raw-bytes (get-bytevector-n port (- compressed 2))))
-           (let* ((cexpanded (carmack-expand raw-bytes len))
-                  (uint-list (bytevector->uint-list cexpanded (endianness little) 2)))
-             (assert (= (* 2 64 64) (car uint-list)))
-             (rlew-expand (cdr uint-list)))))
+         (let ((len (u16vector-ref (get-bytevector-n port 2) 0)))
+           (-> port
+               (get-bytevector-n      (- compressed 2))
+               (carmack-expand        len)
+               (bytevector->uint-list (endianness little) 2)
+               cdr                      ; car contains expected size
+               rlew-expand)))
        (get-planestart map-metadata)
        (get-planelength map-metadata)))
 
@@ -251,5 +258,4 @@ else insert the value as given"
 
     (assert (= #xABCD (get-rlew maphead)))
 
-
     (display-tilemap (tile-list->tilemap (car (caddr mapdata))))))