Main.hs

import Language.Haskell.Interpreter
import MyModule

main = do
  r <- runInterpreter interp
  case r of
    Left err -> print $ show err
    Right res -> print res

interp :: Interpreter IntBox
interp = do
  set [searchPath := ["."]]
  loadModules ["*MyModule.hs"]
  setTopLevelModules ["MyModule"]
  interpret ("testIB") (as :: IntBox)

MyModule.hs

{-# LANGUAGE TypeSynonymInstances, FlexibleInstances, DeriveDataTypeable #-}
module MyModule where

import Data.Typeable

data IntBox = IB Int
            deriving (Typeable, Show)

testIB = IB 1