+ ((prim (and lexed-ast (symbolp (car lexed-ast)) (find-prim (car lexed-ast)))))
+ (cond
+ ((and arg-countdown (zerop arg-countdown)) (append (when prev-item (list prev-item)) lexed-ast))
+ ((and prim (prim-is-infix prim))
+ (parse-prim prim lexed-ast prev-item arg-countdown)) ; Special casing infix prims is cleaner
+ (t
+ (append
+ (when prev-item (list prev-item))
+ (cond
+ ((not lexed-ast) nil)
+ ((stringp (car lexed-ast))
+ (parse-internal (cdr lexed-ast)
+ :prev-item (car lexed-ast)
+ :arg-countdown (when arg-countdown (1- arg-countdown))))
+ ((numberp (car lexed-ast))
+ (parse-internal (cdr lexed-ast)
+ :prev-item (coerce (car lexed-ast) 'double-float)
+ :arg-countdown (when arg-countdown (1- arg-countdown))))
+ ((eql (intern "(" :keyword) (car lexed-ast)) (parse-parened-expr (cdr lexed-ast) arg-countdown))
+ ((eql (intern ")" :keyword) (car lexed-ast)) (error "Closing parens has no opening parens"))
+ ((eql :let (car lexed-ast)) (parse-let (cdr lexed-ast) arg-countdown))
+ ((eql :[ (car lexed-ast)) (parse-block (cdr lexed-ast) arg-countdown))
+ (prim
+ (when (prim-structure-prim prim)
+ (error "This doesn't make sense here"))
+ (parse-prim prim lexed-ast nil arg-countdown))
+ (t (error "Couldn't parse ~S" lexed-ast))))))))
+
+(defun parse-let (lexed-ast arg-countdown)
+ (when (not (keywordp (car lexed-ast))) (error "Needed a keyword for let"))
+ (let*
+ ((half-parsed-remainder (parse-internal (cdr lexed-ast) :arg-countdown 1)))
+ (let
+ ((*dynamic-prims* (cons (list :name (car lexed-ast)) *dynamic-prims*)))
+ (parse-internal
+ (cdr half-parsed-remainder)
+ :arg-countdown (when arg-countdown (1- arg-countdown))
+ :prev-item (list :let (car lexed-ast) (car half-parsed-remainder))))))
+
+(defun parse-prim (prim lexed-ast prev-item arg-countdown)
+ (let*
+ ((num-args (- (prim-num-args prim) (if (prim-is-infix prim) 1 0)))
+ (half-parsed-remainder (parse-internal (cdr lexed-ast) :arg-countdown num-args)))
+ (parse-internal
+ (nthcdr num-args half-parsed-remainder)
+ :arg-countdown (when arg-countdown (if (prim-is-infix prim) arg-countdown (1- arg-countdown)))
+ :prev-item