On 30 March 2011 09:37, Simon Meier
Probably some more filtering of this sequence is required to cater for repeated calls to GHC. I guess that, as long as progress never goes from 100% to something below, the user will be happy about the progress estimate. Moreover, the chance that such a pattern occurs where it doesn't indicate some interesting progress is reasonably low.
An coworker of mine back in the day had a great hack for reporting the progress of loading up a GUI application written in his framework. Basically, he watched what logging calls were made by the app. He also kept a record of the strings that got logged *last* time the app started up, as well, and maintained a pointer into it during app startup. If he saw a match (to within some edit distance) between a newly-logged message and previously-logged one occurring **after the pointer** then he moved the pointer forward to that previously-logged entry. He could then get a % estimate of how started the program was by looking at how far the pointer had gone along the log from last time. The really cute thing about this is that as the user of his GUI framework you didn't have to worry about progress reporting at all - just write a few logging calls as you would normally and it just magically worked :-) Unfortunately I can't see a way to apply this to Cabal without a lot of engineering (e.g. Hackage could record the build output stderr/stdout for a package and then transmit it down to a new client building a package). Probably not worth it! Cheers, Max