Re: [Haskell-cafe] ANNOUNCE: iterIO-0.1 - iteratee-based IO with pipe operators

2011-05-06 Thread Tom Brow 

 At least one thing I've concluded is that it really should be
 presented as two concepts, rather than three.  So we should talk
 about, e.g., producers, consumers, and pipeline stages that do both.


I think that's a great idea.

I'd been thinking about using the terms Source and Sink, but Source is
 very overloaded, and SinkSource doesn't exactly roll off the tongue
 or evoke a particularly helpful intuition.


One good thing I can say for the Enumerator/Iteratee nomenclature is that it
nicely connotes the inversion of control (i.e., the push data flow) that
enumerator is all about. Enumera*tor** *feeds Itera*tee* -- subject, verb,
object. Producer/Consumer connotes the same by allusion to the
producer-consumer pattern of thread synchronization.

Tom

On Fri, May 6, 2011 at 9:47 AM, dm-list-haskell-c...@scs.stanford.eduwrote:

 This is a question I struggled a lot with.  I definitely agree that
 the terms are pretty intimidating to new users.

 At least one thing I've concluded is that it really should be
 presented as two concepts, rather than three.  So we should talk
 about, e.g., producers, consumers, and pipeline stages that do both.

 I'd been thinking about using the terms Source and Sink, but Source is
 very overloaded, and SinkSource doesn't exactly roll off the tongue
 or evoke a particularly helpful intuition.

 In the end, I decided just to come up with new terms that wouldn't
 carry any pre-conceptions (e.g., what's an Inum?), and then build
 the intuition through copious documentation...

 I'm open to suggestion here.  I've already overhauled the naming
 conventions in the library once.  Initially I used the names EnumI and
 EnumO for Inum and Onum.  I think the old names were much worse,
 especially since Enum is a fundamental typeclass that has absolutely
 nothing to do with enumerators.

 David

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[Haskell-cafe] Pattern matching on lazy bytestrings: how does it work?

2011-04-23 Thread Tom Brow 
I noticed today that I can pattern match against lazy bytestrings when using
the OverloadedStrings extension:

import Data.ByteString.Char8 ()

 import Data.ByteString.Lazy.Char8


 f :: ByteString - Bool

 f abc = True

 f _ = False


 main = do

 print $ f $ fromChunks [abc]

 print $ f $ fromChunks [a,bc]


When I run the above, I get:

True

 True


Given that pattern matching is based on data constructors, how is it
possible that (Chunk abc Empty) and (Chunk a (Chunk bc Empty)) match
the same pattern?

Tom
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