hsc2hsで生成したバインディングを使うと全然関数型らしくないものができてしまった（途中）

hs-groonga-main.hs

import Bindings.Groonga
import Foreign.C.String
import Foreign.C.Types()
import Foreign.Ptr
import Foreign.Storable()
import System.Directory

main :: IO ()
main = do
  -- init context
  rc <- c'grn_init
  ctx <- c'grn_ctx_open rc
  -- comand version
  com <- c'grn_ctx_get_command_version ctx
  putStrLn $ show com
  -- encoding
  enc <- c'grn_get_default_encoding
  cenc_str <- c'grn_encoding_to_string enc
  enc_str  <- peekCString cenc_str
  putStrLn enc_str
  -- show Groonga version
  showVersion
  let dbpath = "db/test.db"
  file <- doesFileExist dbpath
  if file then do
    -- db open
    dbname <- newCAString dbpath
    db <- c'grn_db_open ctx dbname
    showErrbuf ctx
    putStrLn $ show db
  else do
    -- db create
    dbname <- newCAString dbpath
    db <- c'grn_db_create ctx dbname nullPtr
    showErrbuf ctx
    putStrLn $ show db

showErrbuf :: Ptr C'_grn_ctx -> IO ()
showErrbuf ctx = do
  let char = p'_grn_ctx'errbuf ctx
  clog <- peekCString char
  putStrLn clog

showVersion :: IO ()
showVersion = do
  version <- c'grn_get_version
  ver <- peekCString version
  putStrLn ver