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