On 11 June 2012 12:37, David Kastrup <d...@gnu.org> wrote: > What is a vlist?
vlist is a data type introduced around guile 2.0. You will find it documented in the Guile Reference under Compound Data Types. They are growable and provide vector-like access performances and memory locality. >>> Now it would be possible when the type lattice gets extended to store >>> the new entries in a hashtable and go from there. >> >> Why not use a hash for everything? Unless your initial lattice is >> very large there would be relatively small loss in performance. > > About double the memory impact (vector->1 cell, hash table->1 cell per > hash bucket+1 additional cons cell per element) and much slower copying. > And quite slower access. > With these concerns your only options are really vlist or implementing growable vector. >>> Or put them into a >>> list, and reallocate on first access beyond the existing element. That >>> seems rather contorted. >> >> You mean “put them into a /vector/”? > > No, since a vector can't be grown. This would basically switch the data > structure between "write" and "read" mode, where "write mode" grows the > list of additions, and "read mode" accesses the vector. Switching from > write to read entails creating a newly allocated vector and copying the > new additions from the list as well as the old vector into it. I see, that is rather contorted :-)
