[Haskell-cafe] Re: Handles with their IOMode in their type

Jason Dagit dagit at codersbase.com
Thu Dec 10 02:51:06 EST 2009

On Wed, Dec 9, 2009 at 6:00 PM, Brandon S. Allbery KF8NH <
allbery at ece.cmu.edu> wrote:

> On Dec 9, 2009, at 16:51 , Bas van Dijk wrote:
>> I will change the types to:
>> stdin :: Handle ReadMode
>> stdout :: Handle WriteMode
>> stderr :: Handle WriteMode
>> Or are there scenarios where people want to write to stdin or read
>> from stdout or stderr?
> These situations *do* come up; the controlling terminal for a program is
> open read/write on all 3 file descriptors initially, ands programs like
> more/less/pg rely on this and do their I/O on stdout.  Additionally, on *BSD
> pipes are actually socketpairs and therefore bidirectional, and a small
> number of programs rely on this.

I was surprised to hear this, so I did some fact checking:

Looks like you're telling the truth.  Learn something new every time I read
Haskell-Cafe :)

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.haskell.org/pipermail/haskell-cafe/attachments/20091210/7511dd01/attachment.html

More information about the Haskell-Cafe mailing list