Re: [Isarmathlib-devel] Haskell

[Slawomir Kolodynski]

> How do you debug Haskell programs?

I don't, if they compile, they work...

More seriously, it's a major pain. I don't use hat, although I guess it would 
be useful to learn. My technique is that if there is a problem I run suspected 
functions from GHCi to see if they work as expected. If something fails in 
tiddlyisar, it is usually the parser. Parsec gives the line number, so I know 
more or less the theorem where the problem happens (don't forget to add 30 or 
so to the line Parsec gives, tiddlyisar's parser gets the theory file without 
that initial comment with the license). Then I try to parse that part of the 
text using my knowledge on how it should be parsed. After a couple of hours I 
know what is wrong...
This works only if you know the code and how it is supposed to work very well. 
I don't think I would be able to use this method to debug Haskell code written 
by someone else. But hey, there are lots of people smarter than me, and maybe 
you are one of them... Good luck.

One thing that would help in debugging is adding some <?> combinators to the 
parser. I will do that next.

Slawek