Consider:
(deftype int32 (fixint 32 32 #t)
(defunion (list 'a) Nil (Cons 'a))
In order to create a value of type int32-list
(define ilist (Cons 100))
works fine.
If I write:
(deftype i32list (list int32))
(define ilist Nil)
The type if ilist is not very clear, and I think we must pick the most
general (or original) type.
That is,
(define ilist Nil) ;ilist: (list 'a)
(define jlist (Cons 100)) ; ilist: (list int)
(define klist:i32list Nil) ; ilist: i32list
Since deftype really only creates aliases, how about
(if #t ilist klist) ??
Now consider:
(defstruct (llist 'a) payload:'a link:(ref (llist 'a)))
; llist for linked list
(deftype i32llist (llist int))
(define mlist (i32llist 100 nextnode))
works fine.
But,
(define nlist ((llist int32) 100 nextnode))
CANNOT be allowed. This is because, if in-place specialization is
allowed, I should also be able to write:
(define nlist ((llist (fixint 32 32 #t)) 100 nextnode))
and the rule for apply should be changes to
apply : (exprs) | (type types)
This obviously creates an ambiguity in the case of ident for expr vs
type. The main problem here is that apply is doing a little too many things.
Swaroop.
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