capabilities of GHC API

Simon Marlow simonmarhaskell at
Tue May 22 03:49:55 EDT 2007

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.


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