On Feb 2, 2008, at 18:41 , Ben Butler-Cole wrote:
No instance for (Bounded a) arising from use of `maxBound' at Hbot.hs:6:34-41 (...) My (clearly flawed) understanding of the signature I've specified for 'turn' means *exactly* that a is Bounded.
The problem is that the scope of a is the type signature; it does *not* extend to the definition. You can try omitting the type on maxBound and minBound, or you can enable the scoped type variables extension ( http://www.haskell.org/ ghc/docs/latest/html/users_guide/other-type-extensions.html#scoped- type-variables ). -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH