backup

src/canvas.wast

@@ -74,13 +74,18 @@
   ))
 
   (func $canvas_get_absolute_origin_aux (param $canvas (ref $canvas)) (param $abs_orig (ref $point)) (result (ref $point))
+    (local $parent (ref null $canvas))
+    (local.set $parent (struct.get $canvas $parent (local.get $canvas)))
     ;; if there's no parent, we're the `root` canvas
-    (if (result (ref $point)) (ref.is_null (struct.get $canvas $parent (local.get $canvas))) (then
+    (if (result (ref $point)) (ref.is_null (local.get $parent)) (then
       local.get $abs_orig
     )
-    ;; otherwise, we have a parent, and our absolute origin is the sum of the current absolute origin and the one of our parent, hence the recursive call
+    ;; otherwise, we have a parent, and our absolute origin is the sum of the current absolute origin, our absolute origin and the one of our parent, hence the recursive call
     (else
-      (call $canvas_get_absolute_origin_aux (struct.get $canvas $parent (local.get $canvas)) (call $point_add (local.get $abs_orig) (struct.get $canvas $origin (local.get $canvas))))
+      (call $canvas_get_absolute_origin_aux
+        (ref.cast (local.get $parent) (rtt.canon $canvas))
+        (call $point_add (local.get $abs_orig) (struct.get $canvas $origin (local.get $canvas)))
+      )
     ))
     return
   )

src/list.wast

@@ -0,0 +1,105 @@
+(module $list
+
+  (type $list (struct
+    (field $head i32)
+    (field $tail (ref null $list))
+  ))
+
+  (func $nil (result (ref null $list))
+    (return (ref.null $list))
+  )
+
+  (func $cons (param $head i32) (param $tail (ref null $list)) (result (ref $list))
+    (struct.new $list (local.get $head) (local.get $tail) (rtt.canon $list))
+    return
+  )
+
+  (func $is_nil (param $list (ref null $list)) (result i32)
+    (block $l (result i32)
+      i32.const 1
+      (br_on_null $l (local.get $list))
+      drop
+      drop
+      i32.const 0
+    )
+    return
+  )
+
+  (func $head (param $list (ref $list)) (result i32)
+    (struct.get $list $head (local.get $list))
+    return
+  )
+
+  (func $tail (param $list (ref $list)) (result (ref null $list))
+    (struct.get $list $tail (local.get $list))
+    return
+  )
+
+  (func $length_aux (param $acc i32) (param $list (ref null $list)) (result i32)
+    (if (result i32) (call $is_nil (local.get $list))
+      (then
+        (return (local.get $acc))
+      ) (else
+        (return
+          (call $length_aux
+                (i32.add (local.get $acc) (i32.const 1))
+                (call $tail (ref.as_non_null (local.get $list)))
+          )
+        )
+      )
+    )
+  )
+
+  (func $length (param $list (ref null $list)) (result i32)
+    (return (call $length_aux (i32.const 0) (local.get $list)))
+  )
+
+  (func $nth_aux (param $list (ref null $list)) (param $n i32) (result i32)
+    (if (call $is_nil (local.get $list))
+      (then unreachable)
+    )
+    (if (result i32) (i32.eq (i32.const 0) (local.get $n))
+      (then (call $head (ref.as_non_null (local.get $list))))
+    (else
+      (call $nth_aux
+        (call $tail (ref.as_non_null (local.get $list)))
+        (i32.sub (local.get $n) (i32.const 1))
+      )
+    ))
+    return
+  )
+
+  (func $nth (param $list (ref null $list)) (param $n i32) (result i32)
+    (if (i32.lt_s (local.get $n) (i32.const 0))
+      (then unreachable)
+    )
+    (return (call $nth_aux (local.get $list) (local.get $n)))
+  )
+
+  (type $mapf (func (param i32) (result i32)))
+
+  (func $map (param $f (ref $mapf)) (param $list (ref null $list)) (result (ref null $list))
+    (if (result (ref null $list)) (call $is_nil (local.get $list))
+      (then (call $nil))
+    (else
+      (call $cons
+        (call_ref (call $head (ref.as_non_null (local.get $list))) (local.get $f))
+        (call $map (local.get $f) (call $tail (ref.as_non_null (local.get $list))))
+      )
+    ))
+    return
+  )
+
+  (func (export "test_should_be_nil") (result i32)
+    (return (call $is_nil (call $nil)))
+  )
+
+  (func (export "test_should_not_be_nil") (result i32)
+    (return
+      (call $is_nil
+        (call $cons (i32.const 42) (call $nil))))
+  )
+)
+
+(assert_return (invoke "test_should_be_nil") (i32.const 1))
+(assert_return (invoke "test_should_not_be_nil") (i32.const 0))