[Haskell-beginners] Invoking ghci with hackage modules

[Sylvain Henry]

Hi,

With Stack:

 > stack ghci --resolver=lts-18.28 --package=random arrows.hs

You can use Stack's script feature to specify resolver and packages 
directly in the .hs file. See 
https://www.wespiser.com/posts/2020-02-02-Command-Line-Haskell.html for 
some examples.

Cheers,
Sylvain


On 16/06/2022 01:39, Lists0 wrote:
> Hi all,
>
> a very basic question, that I cannot solve alone:
> How do I load modules from hackage into ghci ?
> Say, I have a module arrows.hs :
>
> {-# LANGUAGE Arrows #-}
>
> module Main where
> import Control.Arrow
> import Control.Monad
> import qualified Control.Category as Cat
> import Data.List
> import Data.Maybe
> import System.Random
>
>
> I get the error in ghci:
>
> % ghci arrows.hs
> GHCi, version 8.10.6: https://www.haskell.org/ghc/  :? for help
> [1 of 1] Compiling Main             ( arrows.hs, interpreted )
>
> arrows.hs:9:1: error:
>      Could not find module ‘System.Random’
>      Use -v (or `:set -v` in ghci) to see a list of the files searched
> for. |
> 9 | import System.Random
>    | ^^^^^^^^^^^^^^^^^^^^
> Failed, no modules loaded.
> Prelude>
>
>
> System.Random is in the package "random" from hackage, where the other
> modules are in the package base.
>
> I cannot find a solution in the doku that works :-(
>
> Thanks for help!
>
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