Exceptions

[Simon Marlow]

On 11 April 2006 13:35, John Meacham wrote:

> On Tue, Apr 11, 2006 at 01:24:07PM +0100, Simon Marlow wrote:
>> Attached is another variant of the extensible exceptions idea, it
>> improves on the previous designs in a couple of ways:  there's only
>> one catch & throw, regardless of what type you're throwing or
>> catching. There is an extensible hierarchy of exceptions, and you
>> can catch and re-throw subclasses of exceptions.
> 
> I made the catch and throw separate so the decision as to whether to
> include imprecice exceptions and extensible extensions can be made
> independently.
> 
> that and
> 
> throw x /= ioError x
> 
> ioError x >> return ()  -> IO _|_  (only _|_ when IO action executed)
> throw x >> return () -> _|_
> 
> ioError x `seq` ()  -> ()
> throw x `seq` () -> _|_

yes, when I say "one throw" I was referring to the argument type, not
the return type.  We should still have ioError - although it would
probably be better named throwIO:

http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Excep
tion.html#v%3AthrowIO

(the docs for throwIO also mention the strictness property you described
above)

Cheers,
	Simon