Initialize function by file contents at compile time

Question

Is there a way to initialize a function

someText :: Text

which value will be stored in a file available at compile time?

I thought I could use TH for that, but for now I just found

embedFile :: FilePath -> Q Exp
runQ :: Quasi m => Q a -> m a

I can only unwrap Q into IO:

instance Quasi IO    
instance Quasi Q

I guess I need Identity instance of Quasi, but there is no one.

Answer 1

Isn't this just

someText :: Text
someText = $(embedStringFile "path/to/file")

Am I missing something?

(It's the TH splice itself that turns Q Exp into some other type at run-time. You shouldn't need any typeclass instances or anything...)

Answer 2

# foo.txt
barbazblub

module FileText where
import Language.Haskell.TH

fileText :: FilePath -> Q Exp
fileText fp = LitE . StringL <$> runIO (readFile fp)

{-# LANGUAGE TemplateHaskell #-}
module Foo where

import FileText

main = putStrLn $(fileText "foo.txt")

$ runhaskell Foo.hs 
barbazblub