Mutability vs Laziness
Carried over form IRC to placeholder the conversation as I saw it: We define the following in S06 as immutable types: ListLazy 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 JunctionSets with additional behaviours PairSeq 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: Mutability: true, false Laziness: true, false Ordered: true, false There are, thus, eight types of containers, but two (unordered, mutable, lazy/eager) don't really work very well, so let's say 6: 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, though we don't have such a type. Basically, this is something like any(a..b). The real question in my mind, though is this: do we need to call something Lazy (as we currently do in S29), or should we just call it List or Array depending on its mutability?
Re: Mutability vs Laziness
Aaron Sherman wrote: It seems to me that there are three core attributes, each of which has two states: Mutability: true, false Laziness: true, false Ordered: true, false I think there's a 4th: exclusivity: whether or not duplicate elements are permitted/exposed (i.e. the difference between a set and a bag). This is orthogonal to orderedness.
Re: Mutability vs Laziness
Aaron Sherman wrote: Carried over form IRC to placeholder the conversation as I saw it: We define the following in S06 as immutable types: ListLazy 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 JunctionSets with additional behaviours PairSeq 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.
