Hi The reason, as Matt discovered, is that it has module Queens where, not module Main where. Could we perhaps get a better error message on this one? Thanks Neil On 8/16/07, Neil Mitchell wrote:

Hi,

Using the attached program:

-------------------------------------------------------------------------------- D:\Temp>yhc Queens.hs Compiling Queens ( Queens.hs )

D:\Temp>yhi Queens.hbc Assertion failed: pinfo->info.tag == I_PINFO, file d:\sources\yhc\current\src\ru ntime\bckernel\mutins.h, line 295

This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information. --------------------------------------------------------------------------------

This also shows we have assertions on in the release "scons yhi" code, I guess they can stay in for now, but we really do need an optimisation mode.

Program from Matt :-)

Thanks

Neil

----------- Queens.hs --------------

module Queens where

main = nsoln 9

len :: [a] -> Int len [] = 0 len (x:xs) = 1 + len xs

nsoln :: Int -> Int nsoln nq = len (gen nq) where gen :: Int -> [[Int]] gen 0 = [[]] gen n = [ (q:b) | b <- gen (n-1), q <- [1,2,3,4,5,6,7,8,9] {-toOne nq-}, safe q 1 b]

safe :: Int -> Int -> [Int] -> Bool safe x d [] = True safe x d (q:l) = x /= q && x /= q+d && x /= q-d && safe x (d+1) l

toOne :: Int -> [Int] toOne n = if n == 1 then [1] else n : toOne (n-1)