Yes, that does not look very nice but it should work. In a private
response, I was also pointed out the alternative solution of using
case together with `seq` to trigger evaluation, which looked like the
default way to me (what else is seq for?):
| case monstrousDS `seq` True of True -> hPutStr stderr "ok."
I first tried to wrap this in a `force' function, thereby proving that
I still haven't grasped the concept entirely. (-:
But maybe it is possible to make a primitive of this in the same way
as has been done with assert?
Anyway thanks for all your help,
Matthias
"Jan de Wit"
Hi,
I want to do something like:
| main = do | monstrousDataStructure <- monstrousComputation | hPutStr stderr "success!" | ...
The important point is that I want to make sure that the computation has terminated and not failed before I go to `...'. If the monstrous data structure has a 'serious' equality (not always returning True), you can try:
| main = do | monstrousDataStructure <- monstrousComputation | if (monstrousDataStructure == monstrousDataStructure) then | hPutStr stderr "success!" | else | hPutStr stderr "failure?"
The idea is that comparing for equality walks over the entire data structure, forcing evaluation because every location has to be inspected.
Hope this helps, Jan de Wit
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