On 11 June 2012 20:20, David Kastrup <d...@gnu.org> wrote: >> P.S.: I still need to look at vlists. They might already address this >> issue, though I can't use them in Guile 1.8. > > No, the "immutable" angle would make them unsuitable again.
Note that vlists are only immutable in the sense that you can not modify the value of a slot already allocated. You can modify the object that a slot points to and you can extend a vlist as much as you like. Multiple vlists can even share tails. For example, this session modifies the object in slot 0 of the vlist: > (use-modules (ice-9 vlist)) > (list->vlist '((a b) (c d) (e f))) $1 = #<vlist ((a b) (c d) (e f))> > (vlist-ref $1 0) $2 = (a b) > (set-cdr! $2 '(boo)) > $1 $3 = #<vlist ((a boo) (c d) (e f))> > Scheme/Guile vectors are fixed size. Now I have a situation where I > have a basic type lattice with records stored in vectors, and this type > lattice may be extended dynamically (which typically happens at the > start of a whole file, for potentially multi-file runs). >From this I gather that your use case only appends to the lattice, if so, vlist is suitable for that task. > Cough, cough. Standard vectors are not growable. Which is the original > problem of this thread, never mind Lua. True, but a growable vector is a tiny step away from the standard vector. > hashtables have additional indirection > through hash buckets and coalescing lists This is fairly standard for a hash table. I would be quite surprised if the hash table part of a Lua table did not also use buckets. > Except that this one isn't. Why not? You take a vector and a hash table, store your values in them, and grow either as needed. This is not a complicated type.
