[Haskell-beginners] Import errors from a very simple program

[Daniel Trstenjak]

Hi John,

if I'm understanding you correctly, you're installing packages by hand
with 'cabal install' and then calling 'ghc' by hand for your source file.

'ghc' won't automatically use the packages you've installed with 'cabal install',
but you've to add them to the 'ghc' call. Your compile error seems to indicate,
that the 'cassava' and 'vector' packages haven't been given to the 'ghc' call.

But most likely it isn't worth the hassle doing this and it is a lot
easier to just create a default cabal file with 'cabal init'. Then you
can add the 'cassava' and 'vector' packages as dependencies and build
the packages and your source file with 'cabal new-build'.

Greetings,
Daniel