I am attempting my first sandbox build with a cabal package (Chart) and I don't know what to put in my cabal.config file after looking at these sites:

https://www.haskell.org/cabal/users-guide/developing-packages.html

http://coldwa.st/e/blog/2013-08-20-Cabal-sandbox.html

https://wiki.haskell.org/Cabal-Install

I am getting the following build error:

Building chartHask-0.1.0.0...

Preprocessing executable 'chartHask' for chartHask-0.1.0.0...

[1 of 1] Compiling Main             ( Main.hs, dist/build/chartHask/chartHask-tmp/Main.o )

Main.hs:5:1: error:

    Failed to load interface for ‘Graphics.Rendering.Chart.Backend.Cairo’

    Perhaps you meant

      Graphics.Rendering.Chart.Backend.Impl (from Chart-1.9)

      Graphics.Rendering.Chart.Backend.Types (from Chart-1.9)

      Graphics.Rendering.Chart.Backend (from Chart-1.9)

    Use -v to see a list of the files searched for.

So, Maybe I'm dumb or it's not explicit (or both) on how to add a package to my cabal.config so it can find it and build.  I tried adding this to my cabal.config to no avail:

documentation: True

constraints: Chart >= 1.9

Main.hs (from Chart example:

module Main where

import Graphics.Rendering.Chart.Easy

import Graphics.Rendering.Chart.Backend.Cairo

signal :: [Double] -> [(Double,Double)]

signal xs = [ (x,(sin (x*3.14159/45) + 1) / 2 * (sin (x*3.14159/5))) | x <- xs ]

main = toFile def "example1_big.png" $ do

    layout_title .= "Amplitude Modulation"

    setColors [opaque blue, opaque red]

    plot (line "am" [signal [0,(0.5)..400]])

    plot (points "am points" (signal [0,7..400]))

Or should I be using Stack? (probably private email or new thread question)

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