On Fri, Aug 10, 2007 at 01:32:48PM -0300, Isaac Dupree wrote:
GHC in its RTS already throws Nontermination exception in some cases. I think it would be nice if, when the compiler detected nontermination, to replace it with an exception and emit a warning message (hmm... if GHC Core loses source code information, a warning message might be difficult). Is there any intentional use of certain nontermination?
One possible use for nontermination would be as a workaround for something like Catch (which defines its own workarounds, but if it didnt...). Catch complains if your code calls error, so you could define your own: myerror :: String -> a myerror s = myerror s The type of this function guarantees that it is either non-terminating or generates an exception, so if powerful static checking prevented a programmer from writing an exception-generating code, the desperate programmer always has the fallback of generating non-terminating code (a good reason for allowing error in the language, I suppose). -- David Roundy Department of Physics Oregon State University