> I don't know what to actually do with this after putting it in a *.lhs file.
You can :load *.lhs into ghci the same way you load .hs-files. I'm not sure why you were getting the ambiguous type errors. I didn't: test1 :: StateT Integer Identity (Integer, Integer) test2 :: StateT [Char] Identity ([Char], [Char]) test3 :: StateT Integer (StateT [Char] Identity) (Integer, [Char]) test5 :: StateT Integer IO () test7 :: StateT Integer (StateT [Char] Identity) (Integer, [Char]) Hope that helps. Arseniy. On 2 January 2012 06:03, Steve Horne <sh006d3...@blueyonder.co.uk> wrote: > I'm having another go at figuring out Monad Transformers, starting at the > same point I've started and stopped the last couple of times. That's this > tutorial... > > http://blog.sigfpe.com/2006/05/grok-haskell-monad-transformers.html > > Onion layers, lift etc - I get that. But I've never actually got anything to > work - and therefore never built the confidence to move on. > > Problem 1 - this is literate Haskell. I've tried feeding it to haddock - all > I get is an error about it lacking a main. I don't know what to actually do > with this after putting it in a *.lhs file. > > No big deal, but... > > Problem 2 - even cutting the code out, shoving it in a *.hs file, and > :loading it into GHCi, I still get a lot of errors. > > For the functions test1 and test2, the fixes were explicit type signatures. > Easy enough to figure out... > > test1 :: State Int (Int, Int) > test2 :: State String (String, String) > > I guess the basic issue is the same with test3 (and though I haven't tried > the others today, probably test5 and test7 too). The trouble there is that I > don't know what those type signatures should be because I don't know that > much about monad transformers and how they can work. I can see what's going > on in the body of test3, but that is a very small amount of understanding - > the type signatures are important. And I can't use :type because GHCi is > rejecting the code. > > > In short... HELP!!! > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
