Haskell Cookbook

How to do it...

1. Create a new project using the simple Stack template:

        stack new fibonacci-state simple

2. Open fibonacci-state.cabal and add packages mtl and containers to the build-depends subsection of the executable section:

         executable fibonacci-state         hs-source-dirs: src         main-is: Main.hs         default-language: Haskell2010         build-depends: base >= 4.7 && < 5                 , mtl                 , containers

3. Build the project so that the dependent packages will be pulled by stack:

        stack build

4. Open src/Main.hs. We will be editing this file.
5. Import the following modules after initial module declaration:

        import Control.Applicative        import Control.Monad.State        import Data.Map.Strict as M

The module Control.Monad.State defines the state, monad.Data.Map.Strict defines the strict ...