Hi all, The generated C source hs.out_code.c cannot be compiled due to an undeclared variable. Here is the snippet code which can reproduce the issue. import Data.Array.IO main = do arr <- newIOArray (0,42) 0 :: IO (IOArray Int Int) print 13 Here is the excerpt from jhc's output: Writing "hs.out_code.c" Running: gcc '-std=gnu99' -D_GNU_SOURCE '-falign-functions=4' -ffast-math -Wextra -Wall -Wno-unused-parameter -fno-strict-aliasing -o hs.out hs.out_code.c -DNDEBUG -O3 '-D_JHC_GC=_JHC_GC_JGC' hs.out_code.c: In function ‘ftheMain’: hs.out_code.c:1867:27: error: ‘v119549094’ undeclared (first use in this function) hs.out_code.c:1867:27: note: each undeclared identifier is reported only once for each function it appears in hs.out_code.c: In function ‘fx57580221’: hs.out_code.c:1886:24: warning: comparison between signed and unsigned integer expressions hs.out_code.c:1889:9: warning: statement with no effect hs.out_code.c:1926:17: warning: statement with no effect jhc: user error (C code did not compile.) The whole session is enclosed as `typescript'. Btw, jhc 7.7 cannnot be compiled on ghc 7.0.4 smoothly. I add `{-# LANGUAGE TypeFamilies #-}' and `import Data.Generics hiding (empty)' to get it compiled. -- Regards, Ray ---------------------------- site: http://maskray.tk ----------------------------