Template Haskell Errors

error

[1 of 2] Compiling TH               ( TH.hs, interpreted )

TH.hs:11:52:
    Couldn't match type ‘Exp’ with ‘Body’
    Expected type: [Body]
      Actual type: [Exp]
    In the third argument of ‘zipWith’, namely ‘fnBodies’
    In the expression:
      zipWith (\ p b -> Clause [p] b []) patterns fnBodies

TH.hs:13:29:
    Couldn't match expected type ‘Pat’ with actual type ‘Name’
    In the expression: x'
    In the first argument of ‘Clause’, namely ‘[x']’

TH.hs:13:33:
    Couldn't match expected type ‘Body’ with actual type ‘Exp -> Exp’
    Probable cause: ‘appBody’ is applied to too few arguments
    In the second argument of ‘Clause’, namely ‘appBody’
    In the expression: Clause [x'] appBody []

TH.hs:14:23:
    Couldn't match expected type ‘Exp -> Exp’ with actual type ‘Exp’
    The function ‘VarE’ is applied to two arguments,
    but its type ‘Name -> Exp’ has only one
    In the first argument of ‘AppE’, namely
      ‘(VarE (mkName "bigBadMathProblem") (VarE x'))’
    In the expression:
      AppE (VarE (mkName "bigBadMathProblem") (VarE x'))
Failed, modules loaded: none.

Test.hs

{-# LANGUAGE TemplateHaskell #-}
module Test where
import           TH

$(precompute [1..1000])

TH.hs

module TH where

import           Language.Haskell.TH

precompute :: [Int] -> DecsQ
precompute xs = do
  let name = mkName "lookupTable"
      patterns = map intToPat xs
      fnBodies = map precomputeInteger xs
      precomputedClauses =
        zipWith (\p b -> Clause [p] b []) patterns fnBodies
      x' = mkName "x"
      lastClause = [Clause [x'] appBody []]
      appBody = AppE (VarE (mkName "bigBadMathProblem") (VarE x'))
      clauses = precomputedClauses ++ lastClause
  return [FunD name clauses]

intToPat :: Int -> Pat
intToPat = LitP . IntegerL . toInteger

precomputeInteger :: Int -> Exp
precomputeInteger = LitE . DoublePrimL . toRational . bigBadMathProblem

bigBadMathProblem :: Int -> Int
bigBadMathProblem = (*2)