Aaron Sherman wrote: > Carried over form IRC to placeholder the conversation as I saw it: > > We define the following in S06 as immutable types: > > List Lazy Perl list (composed of Seq and Range parts) > Seq Completely evaluated (hence immutable) sequence > Range Incrementally generated (hence lazy) sequence > Set Unordered Seqs that allow no duplicates > Junction Sets with additional behaviours > Pair Seq of two elements that serves as a one-element Mapping > Mapping Pairs with no duplicate keys > > It seems to me that there are three core attributes, each of which has > two states: > > Laziness: true, false > Mutability: true, false > Ordered: true, false
I don't think "Ordered" is an attribute of a collection other than in the abstract, user-centric sense - it is a type parameter difference (though also there are method differences etc). Things that are not ordered map from items to presence (or themselves, if you prefer). Things that are ordered map from array indices to items. > There are, thus, eight types of containers, but two (unordered, mutable, > lazy/eager) don't really work very well, so let's say 6: Mutable sets don't work? I don't see why not. > Ordered, Immutable, Eager: Seq > Ordered, Immutable, Lazy: Range and/or Seq of Range? > Ordered, Mutable, Eager: ? > Ordered, Mutable, Lazy: Array > Unordered, Immutable, Eager: Set > Unordered, Immutable, Lazy: x and/or Set of x? > > In that last example, x is "an unordered range", Sounds a bit like an iterator. Sam.
