Hi,
Can anyone help me get the right output from the program described in

http://www.haskell.org/sitewiki/images/d/dd/TMR-Issue8.pdf

from page 21 and downloadable at

http://www.e-pig.org/darcs/TMR/Issue8/instant-insanity.lhs

? I tried on GHCi 6.6 with options "-fglasgow-exts
-fallow-undecidable-instances" and on GHCi 6.10.1 with options
"-fglasgow-exts -XUndecidableInstances".

All the tests give the expected results except the last (and more
important) one :

:t solutions (u::Cubes)

This one throws an error I can't paste (too many lines for the capacity
of my xterm) but it ends with ..."((Cube G W W B G R ::: Nil) ::: as)
as}' arising from a use of 'solutions' at <interactive>:1:0-19"

This error arises with the initial problem

type Cubes=(Cube1:::Cube2:::Cube3:::Cube4:::Nil)

but it occurs also with the reduced problem

type Cubes=(Cube1:::Cube2:::Nil)

Nevertheless, the minimal problem

type Cubes=(Cube1:::Nil)

works fine.

Thank you for any help.