Random seek support

[maoe]

Do you have any plans to support random seek in this library? I've implemented it in https://github.com/maoe/lzma and am moderately interested in integrating it into your library.

[hvr]

That's a bit awkward, I wasn't aware there was already a lzma lib in the works... why didn't you publish yours yet?

I wanted a lzma-library with minimal dependencies similiar to zlib and bzlib providing a common mid-level foundation for implementing adapters for streaming frameworks (I started with lzma-streams, and I was planning to implement lzma-pipes and lzma-machines as well). My motivation is that I'm investigating how to design streaming-framework independent primitives suitable to be used by conduit/pipes/machines/io-streams.

As I see you're already depending on pipes in your code... are you planning or interested in creating a lzma-pipes package?

As to random-seek support; I don't have any concrete plans as my focus has been streaming sequentially, but I'm interested in random seek support. I'll study your code to learn how you approached this problem.

[maoe]

why didn't you publish yours yet?

Because I was aiming to make it streaming-framework independent, but as you found, it's still using pipes.

I initially started with a custom stream type like you did in this library. But as I implemented the random seek support, I felt I was reinventing the pipes library. Also there was an immediate need for the library, so I just decided to use pipes. I wanted to factor out pipes related code to a separate package but I haven't gotten around to it yet.

are you planning or interested in creating a lzma-pipes package?

Yes, I guess. I'm also interested in machines as well but I'm not sure I have time.

Anyways, I think it would be nice to have random-seek support in this streaming-framework independent library. If it sounds fine to you, I'll give it a try.

[hvr]

Anyways, I think it would be nice to have random-seek support in this streaming-framework independent library. If it sounds fine to you, I'll give it a try.

Sounds totally fine to me. I mostly care about a minimal build-depends footprint, so that lzma could be used by cabal or GHC w/o pulling in non-default packages.

[maoe]

I mostly care about a minimal build-depends footprint, so that lzma could be used by cabal or GHC w/o pulling in non-default packages.

Fair enough. I'll give it a try.

[utdemir]

I'm also in need of this feature, since I couldn't find any compression/decompression library with random seek support on Hakcage. I'd love to help, unfortunately I don't have enough knowledge on C FFI or liblzma; so I'm just putting this here just to say that there's some demand for this feature :).

[maoe]

@utdemir You can find working implementation in https://github.com/maoe/lzma. Incidentally I'm working on random seek support in Rust's liblzma binding. I may be able to work on the support in Haskell next.