capabilities of GHC API

[Simon Marlow]

Frederik Eaton wrote:
>>> If you have GHC-6.6 or greater, try: let n = 2 in GHC.Base.breakpoint ()
>> GHC.Base.breakpoint doesn't work in the HEAD at the moment.  We might want to restore it; I'm not sure.  Since 
>> breakpoints are almost everywhere, it didn't seem necessary. 
> 
> I don't understand the last sentence. Breakpoints didn't seem
> necessary since they are almost everywhere?

Sorry, that was a bit unclear.  In the first implementation of breakpoints you 
had to explicitly annotate breakpoints in your code using GHC.Base.breakpoint. 
In the current implementation, the system adds a breakpoint to every 
subexpression, and you enable them individually via GHCi commands.  So there's 
no need to use GHC.Base.breakpoint (and indeed it doesn't work now).  See the 
docs for details.

Cheers,
	Simon