Making small haskell executables?

Question

Are there any good ways to make small haskell executables? With ghc6 a simple hello world program seems to come to about 370kB (523kB before strip). Hello world in C is abou

Answer 1

With the development branch of GHC (anyone know exactly which version this was added in?):

$ ghc -o hello hello.hs
$ strip -p --strip-unneeded --remove-section=.comment -o hello-small hello
$ du hello hello-small
700 hello
476 hello-small

Add the -dynamic flag for a dynamically linked RTS:

$ ghc -dynamic -o hello hello.hs
$ strip -p --strip-unneeded --remove-section=.comment -o hello-small hello
$ du hello hello-small
24  hello
16  hello-small

See also: http://hackage.haskell.org/trac/ghc/wiki/SharedLibraries/PlatformSupport

For comparison with C:

$ gcc hello.c -o hello
$ strip -p --strip-unneeded --remove-section=.comment -o hello-small hello
$ du hello hello-small
12  hello
8   hello-small

Answer 2

strip -p --strip-unneeded --remove-section=.comment -o your_executable_small your_executable

also try looking at ldd -dr your_executable

Answer 3

The size you're seeing is the Haskell runtime (libHSrts.a), which is statically linked into every Haskell executable. If it were a shared object, like librt.o for C, your binary would be only a few k (the size of a split .o file in the library source).

Short of implementing dynamic linking of libHSrts.a on your platform, you can make your executables smaller via strip.

Answer 4

GHC is statically linking everything (except libraries used by runtime itself, which are linked dynamically).

In the old ages, GHC linked the whole (haskell) library in as soon as you've used something from it. Sometime ago, GHC started to link "per obj file", which drastically reduced the binary size. Judging from the size, you must've been using the newer GHC already.

On the plus side, you already have a lot of stuff in those 500K, like multithreaded core, garbage collector etc.

Add at least garbage collector to your C code, then compare them again :)

Answer 5

Things are changing - keep an eye on this ongoing piece of work.

Answer 6

If the size of your binary really matters, you can use the tool gzexe that packs an (preferably already stripped) executable with the gzip compression. On my 64-bit Linux box, the original hello world program takes 552 KB, after stripping 393 KB, and after stripping and gzipping 125 KB. The darker side of gzipping is in performance -- the executable has to be unpacked first.