Hi,
The GHC manual says that if you pass -cpp to GHC, it runs the C
preprocessor, cpp on your code before compilation
(http://www.haskell.org/ghc/docs/latest/html/users_guide/options-phases.html#c-pre-processor).
But why, in that case, does stringize not seem to work when the -cpp
flag is given?
In my example, test.hs is using the C preprocessor with a simple macro
to trace functions with their name. Running GHC with -cpp gives an
error, but if I run cpp on the file directly then feed it to GHC, I get
no error:
=
*$ ghc --version*
The Glorious Glasgow Haskell Compilation System, version 6.10.3
*$ cat test.hs*
import Debug.Trace
#define TR(f) (trace #f f)
main :: IO ()
main = TR(putStrLn) Hello!
*$ ghc -cpp --make test.hs*
[1 of 1] Compiling Main ( test.hs, test.o )
test.hs:6:14: Not in scope: `#'
*$ cpp test.hs*
# 1 test.hs
# 1 built-in
# 1 command-line
# 1 test.hs
import Debug.Trace
main :: IO ()
main = (trace putStrLn putStrLn) Hello!
*$ cpp test.hs test-cpp.hs*
*$ ghc -cpp --make test-cpp.hs*
[1 of 1] Compiling Main ( test-cpp.hs, test-cpp.o )
Linking test-cpp ...
*$ ./test-cpp*
putStrLn
Hello!
=
What am I missing?
Thanks,
Neil.
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