Hi,

I'm playing around with https://www.stackage.org/haddock/lts-9.0/ghci-8.0.2/GHCi-ObjLink.html to see if I can come up with some sort of hot-loading/plugin system in Haskell.

I've managed to load a shared object (compiled from a Haskell source via -rdynamic) with the following code:

{-# LANGUAGE OverloadedStrings #-}

{-# LANGUAGE MagicHash, UnboxedTuples #-}

module Main where

import GHC.Exts ( addrToAny# )

import GHC.Ptr ( Ptr(..) )

import System.Info ( os, arch )

import Encoding

import GHCi.ObjLink

import Debug.Trace

main :: IO ()

main = do

traceM "before initObjLinker"

initObjLinker

traceM "before loadObj"

loadObj "/Users/saurabhnanda/projects/test-plugins/test-plugins/app/PluginMarkup.o"

traceM "after loadObj"

-- NOTE: I've hardcoded the symbol name that I obtained from running `symbols PluginMarkup.o`

sym <- lookupSymbol "PluginMarkup_foliage_info"

traceM "after lookupsymbol"

traceM (show sym)

I'm getting the following output, which mean that I'm probably getting the Ptr to the function.

before initObjLinker

before loadObj

after loadObj

after lookupsymbol

Just 0x0000000104be49a8

Question is, how do I run the function in the same Haskell environment/runtime? The underlying function is actually `foliage :: UtcTime -> Html`

-- Saurabh.