[Haskell-beginners] HTTP Download -> Save File - non-strict

[Dan Krol]

Hi,

I'm working on an rss file getter. I was wondering if I could get some help
getting files to download and save without holding the entire file in
memory in between. I chose Conduit's version of SimpleHttp only because it
was recommended, and it was the quickest thing I could get to work
correctly because I was eager to get started on this project, so I'd be
happy to switch.

Here's where I define the download and save functions:

https://github.com/orblivion/feedGetter/blob/master/rss.hs#L107

And here's where I use them, getting multiple at a time with async:

https://github.com/orblivion/feedGetter/blob/master/rss.hs#L208

What happens when I run this is that it outputs that it's "Getting" the
file, waits a while (presumably to download the whole thing), then says
it's "Saving". And I checked the file system, it's not there during the
pause. I'm not entirely sure why. Is it my choice of libraries, or the way
I'm using them? Perhaps something to do with async? I just tried content <-
simpleHttp "http://google.com" in ghci, and it does pause for a second, so
I'm guessing this is strict from the getgo. But I've done almost no I/O
before.

Is there a straightforward, canonical option? It seems like there perhaps
should be. But if it comes down to using pipes or conduit, what the heck
I'll try it out, I'd like to learn pipes eventually.

Thanks a lot,

Dan
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