Why is Dynamic Loader package unable to resolve functions? - haskell

Question

I have been trying to use the dynamic loader package which I found from this question. I am very new to Haskell so excuse me if I am making some incredibly rookie mistakes. My problem is that when I attempt to use the resolveFunctions function I get the following error:
DyanmicLoad-exe: /home/ubuntu/DynamicLoadTest/Plugin.o: unknown symbol `ghczmprim_GHCziCString_unpackCStringzh_closure'
DyanmicLoad-exe: user error (Unable to resolve functions!)
I would love it if someone could tell me possibly where I am going wrong here.
Here is my code (I am using the basic stack new structure):
app/Main.hs
Just the main function.
module Main where
import Lib
main :: IO ()
main = libMain
src/Lib.hs
The module is loaded in here.
module Lib
( libMain
) where
import System.Plugins.DynamicLoader
import System.Directory
import Interface
libMain :: IO ()
libMain = do currentDir <- System.Directory.getCurrentDirectory
loadModuleFromPath (currentDir ++ "/Interface.o") Nothing
putStrLn "Loaded Interface"
loadedModule <- loadModuleFromPath (currentDir ++ "/Plugin.o") (Just currentDir)
putStrLn "Loaded Plugin Module!"
resolveFunctions
putStrLn "Resolved Functions"
plugin <- (loadFunction loadedModule "getPlugin") :: IO (JobInterface)
putStrLn "Loaded Plugin"
putStrLn (jobName plugin)
src/Interface.hs
This file is the "plugin interface"
module Interface (
JobInterface (..)
) where
data JobInterface =
JobInterface { jobName :: String
, runJob :: Int -> Int
}
src/Plugin.hs
An example plugin.
module Plugin (
getPlugin
) where
import Interface
getPlugin :: JobInterface
getPlugin = JobInterface "Hello" $ \x -> 1 * x
I am building with stack build followed by stack ghc src/Plugin.hs src/Interface.hs. I am running with stack exec DyanmicLoad-exe.
GHC version is 8.0.1
Full output:
$ stack exec DyanmicLoad-exe
Loaded Interface
Loaded Plugin Module!
DyanmicLoad-exe: /home/ubuntu/DynamicLoadTest/Plugin.o: unknown symbol `ghczmprim_GHCziCString_unpackCStringzh_closure'
DyanmicLoad-exe: user error (Unable to resolve functions!)
Edit 1:
Error with the -dynamic flag on build.
$ stack exec DyanmicLoad-exe
Loaded Interface
Loaded Plugin Module!
DyanmicLoad-exe: /home/ubuntu/DynamicLoadTest/Plugin.o: unhandled ELF relocation(RelA) type 42
DyanmicLoad-exe: user error (Unable to resolve functions!)
Edit 2 .cabal file
name: DyanmicLoad
version: 0.1.0.0
synopsis: Initial project template from stack
description: Please see README.md
homepage: https://github.com/githubuser/DyanmicLoad#readme
license: BSD3
license-file: LICENSE
author: Author name here
maintainer: example#example.com
copyright: 2017 Author name here
category: Web
build-type: Simple
extra-source-files: README.md
cabal-version: >=1.10
library
hs-source-dirs: src
exposed-modules: Lib
, Interface
build-depends: base >= 4.7 && < 5
, dynamic-loader
, directory
default-language: Haskell2010
executable DyanmicLoad-exe
hs-source-dirs: app
main-is: Main.hs
ghc-options: -dynamic -threaded -rtsopts -with-rtsopts=-N
build-depends: base
, DyanmicLoad
default-language: Haskell2010
test-suite DyanmicLoad-test
type: exitcode-stdio-1.0
hs-source-dirs: test
main-is: Spec.hs
build-depends: base
, DyanmicLoad
ghc-options: -threaded -rtsopts -with-rtsopts=-N
default-language: Haskell2010
source-repository head
type: git
location: https://github.com/githubuser/DyanmicLoad