Hi, Is it correct that there is no breakpoint location at list construction place: line "5 then [x]" ? Notice that :steplocal does not stop there before "[1]" is printed when debugging expression "test 1". Thanks, Peter. status:0 peter@metod [721] ~/tmp % cat b.hs hlp x = [-x] test x = if x >= 0 then [x] else hlp x status:0 peter@metod [722] ~/tmp % ghci b.hs GHCi, version 6.8.2: http://www.haskell.org/ghc/ :? for help Loading package base ... linking ... done. Loading package old-locale-1.0.0.0 ... linking ... done. Loading package old-time-1.0.0.0 ... linking ... done. Loading package filepath-1.1.0.0 ... linking ... done. Loading package directory-1.0.0.0 ... linking ... done. Loading package ghciext-0.1 ... linking ... done. [1 of 1] Compiling Main ( b.hs, interpreted ) Ok, modules loaded: Main. *Main> :break 4 Breakpoint 0 activated at b.hs:4:5-10 *Main> test 1 Stopped at b.hs:4:5-10 _result :: [a] = _ 3 test x = 4 if x >= 0 5 then [x] [b.hs:4:5-10] *Main> :steplocal [1] *Main> test (-1) Stopped at b.hs:4:5-10 _result :: [a] = _ 3 test x = 4 if x >= 0 5 then [x] [b.hs:4:5-10] *Main> :steplocal Stopped at b.hs:6:9-13 _result :: [Integer] = _ x :: Integer = -1 5 then [x] 6 else hlp x 7 [b.hs:6:9-13] *Main> :steplocal [1] *Main> :quit Leaving GHCi. status:0 peter@metod [723] ~/tmp %