On: Clojure's Transducers are as fundamental as functi...

[Tuna-Fish]

In languages with more leeway on execution order, this problem can be made to go away. For example, Haskell's stream fusion combines back-to-back calls to list processing functions into a single iteration over the list.

[seanmcdirmid → Tuna-Fish]

Lazy evaluation can also be encoded fairly easily in strict languages using constructs like lazy stream abstractions.

[jeremyjh → seanmcdirmid]

Uh, sure but does any other language have a compiler that actually implements stream fusion?

[gazarsgo → jeremyjh]

Not in the compiler, but enjoy a Microsoft Research paper about Steno, a C# library that claims to be superior to stream fusion (section 8.2): http://research.microsoft.com/pubs/173946/paper-pldi.pdf

In case anyone is unaware, LINQ lets you represent queries as a series of function calls which it represents as a series of Expression objects and an in-memory AST.

[seanmcdirmid → gazarsgo]

There is also the dynamic language run-time (DLR), which as a generalization of LINQ (to support statements) is pretty powerful when writing up these tools on .NET. I use it often in my work.

[DanWaterworth → jeremyjh]

I don't believe GHC actually does implement stream fusion. I think stream fusion happens with rewrite rules.

[riffraff → DanWaterworth]

pardon my ignorance, but what would be the difference between the two? Don't rewrite rules happen in GCH anyway?

[DanWaterworth → riffraff]

Sorry, I should have been clearer. The rewriting happens in GHC, but it's the application programmer who creates the rules. So, stream fusion isn't implemented by the compiler AFAIK.

[riffraff → DanWaterworth]

ah that makes sense, thanks.