I just got the Hlist distribution but could not compile the example files With ghc 6.4 (I use ghci - in eclipse - I did not use ghc with the makefile). I got the following compile time error on module TIP: C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22: Could not deduce (HType2HNat e l n1, HDeleteAtHNat n1 l l'1, HOccurs e (TIP l), HOccurs e2 (TIP l'1)) from the context (HOccurs e1 (TIP l), HType2HNat e1 l n, HDeleteAtHNat n l l', HOccurs e2 (TIP l'), HOccurs e2 (TIP l), HType2HNat e2 l n', HDeleteAtHNat n' l l'', HOccurs e1 (TIP l'')) arising from use of `y' at C:\gisCodev13\HeterogenousList\src/TIP.hs:247:22 Probable fix: add (HType2HNat e l n1, HDeleteAtHNat n1 l l'1, HOccurs e (TIP l), HOccurs e2 (TIP l'1)) to the type signature(s) for `tuple' or add an instance declaration for (HOccurs e (TIP l), HOccurs e2 (TIP l'1)) In the definition of `tuple': tuple (TIP l) = let x = hOccurs (TIP l) l' = hDeleteAtProxy (toProxy x) l y = hOccurs (TIP l') in (x, y) Can anybody quickly see, what is wrong? Andrew U. Frank Professor, Head of Department Geoinformation and Cartography E127 phone: +43 1 588 01 12710 TU Vienna secr. +43 1 588 01 12700 Gusshausstrasse 27-29 fax +43 1 588 01 12799 A-1040 Vienna Austria cellular phone +43 676 41925 72 http://www.geoinfo.tuwien.ac.at/persons/frank/frank.html skype:AndrewUFrank