Haskell package installed but not found

Question

I installed charts, and it seems there, but GHCi does not find it. I tried adding a local sandbox to the command line (-package-db), but still no luck. Any suggestions?

   C:\Users\guthrie>
   C:\Users\guthrie>cabal install diagrams
    Resolving dependencies...
    All the requested packages are already installed:
   diagrams-1.2
   Use --reinstall if you want to reinstall anyway.

I find it in:

  C:\Users\guthrie\.cabal-sandbox\i386-windows-ghc-7.6.3-packages.conf.d
        (diagrams-1.2, diagrams-contrib, -core, -lib, -svg) 

But it works: "cabal repl" or uses the GHC (i) flag "-package-db = ..." to not find it:

C:\Users\guthrie>cabal repl
GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Prelude> :m + Diagrams.Prelude

<no location info>:
    Could not find module `Diagrams.Prelude'
   It is not a module in the current program, or in any known package.
Prelude>

---

To clarify; ignoring cabal calls, using GHC / i directly, and Demo.hs programmatic diagrams:

--  http://projects.haskell.org/diagrams/doc/quickstart.html
--
import Diagrams.Prelude
import Diagrams.Backend.SVG.CmdLine

main = mainWith (circle 1 :: Diagram B R2)

gives:

C:\Users\guthrie\Desktop\xFer\Graphics>ghc --make diagramsDemo.hs

diagramsDemo.hs:7:8:
    Could not find module `Diagrams.Backend.SVG.CmdLine'
    Use -v to see a list of the files searched for.

C:\Users\guthrie\Desktop\xFer\Graphics>ghc --make diagramsDemo.hs -package-db=C:\Users\guthrie\.cabal-sandbox\i386-windows-ghc-7.6.3-packages.conf.d

diagramsDemo.hs:7:8:
    Could not find module `Diagrams.Backend.SVG.CmdLine'
    Use -v to see a list of the files searched for.

Answer 1

As bheklilr said, if ghcirunning with cabal repl, it will only find packages specified as a dependency in the file .cabal.

cabal exec ghci, , .

ghc (cabal build vs. cabal exec ghc), , , --, cabal exec ghc -- -O2 Main.hs. cabal exec bash ghci ghc .

cabal exec Cabal 1.20.