1 files changed, 45 insertions, 0 deletions
diff --git a/entity.scm b/entity.scm
new file mode 100644
index 0000000..cd467eb
--- /dev/null
+++ b/entity.scm
@@ -0,0 +1,45 @@
+(module entity
+    *
+  (import scheme
+	  (chicken base)
+	  (chicken keyword)
+	  (only srfi-1 fold))
+
+  ;; Entities = plists with shared keys (#:type, #:x, #:y, #:width, #:height, ...).
+
+  (define (entity-ref entity key #!optional default)
+    (get-keyword key entity (if (procedure? default) default (lambda () default))))
+
+  (define (entity-type entity)
+    (entity-ref entity #:type #f))
+
+  (define (entity-set entity key val)
+    (let ((cleaned (let loop ((lst entity) (acc '()))
+                     (if (null? lst)
+                         (reverse acc)
+                         (let ((k (car lst))
+                               (v (cadr lst)))
+                           (if (eq? k key)
+                               (loop (cddr lst) acc)
+                               (loop (cddr lst) (cons v (cons k acc)))))))))
+      (cons key (cons val cleaned))))
+
+  (define (entity-update entity key proc #!optional default)
+    (entity-set entity key (proc (entity-ref entity key default))))
+
+  (define (make-player-entity x y width height)
+    (list #:type 'player
+	  #:x x
+	  #:y y
+	  #:width width
+	  #:height height
+	  #:vx 0
+	  #:vy 0
+	  #:gravity? #t
+	  #:on-ground? #f
+	  #:tile-id 29
+	  #:input-map '((left  . (-2 .  0))
+	                (right . ( 2 .  0))
+	                (down  . ( 0 .  2)))))
+)
+