+: set-car! ( obj pair-obj -- )
+ drop dup
+ rot swap car-type-cells + !
+ car-cells + !
+;
+
+: set-cdr! ( obj pair-obj -- )
+ drop dup
+ rot swap cdr-type-cells + !
+ cdr-cells + !
+;
+
+: caar car car ;
+: cadr cdr car ;
+: cdar car cdr ;
+: cddr cdr cdr ;
+
+: nil 0 nil-type ;
+: nil? nil-type istype? ;
+
+: objvar create nil swap , , ;
+
+: value@ ( objvar -- val ) @ ;
+: type@ ( objvar -- type ) 1+ @ ;
+: value! ( newval objvar -- ) ! ;
+: type! ( newtype objvar -- ) 1+ ! ;
+: setobj ( newobj objvar -- ) dup rot swap 1+ ! ! ;
+: fetchobj ( objvar -- obj ) dup @ swap 1+ @ ;
+
+: objeq? ( obj obj -- bool )
+ rot = -rot = and ;
+
+\ ---- Pre-defined symbols ----
+
+objvar symbol-table
+
+: (create-symbol) ( addr n -- symbol-obj )
+ dup 0= if
+ 2drop nil
+ else
+ 2dup drop @ character-type 2swap
+ swap 1+ swap 1-
+ recurse
+
+ cons
+ then
+;
+
+: create-symbol ( -- )
+ bl word
+ count
+
+ (create-symbol)
+ drop symbol-type
+
+ 2dup
+
+ symbol-table fetchobj
+ cons
+ symbol-table setobj
+
+ create swap , ,
+ does> dup @ swap 1+ @
+;
+
+create-symbol quote quote-symbol
+create-symbol define define-symbol
+create-symbol set! set!-symbol
+
+\ ---- Environments ----
+
+objvar global-environment
+
+: enclosing-env ( env -- env )
+ cdr ;
+
+: first-frame ( env -- frame )
+ car ;
+
+: make-frame ( vars vals -- frame )
+ cons ;
+
+: frame-vars ( frame -- vars )
+ car ;
+
+: frame-vals ( frame -- vals )
+ cdr ;
+
+: add-binding ( var val frame -- )
+;
+