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| [[Category:Web|*]]
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| {{Web infobox}}
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| {{Template:Stub}}
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| '''This article is out of date, it refers to GHC 6.8 and Database.SQLite. Please someone update it with a more recent example, if necessary.'''
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| == Deploying statically linked applications ==
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|
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| Linking your applications statically by giving the flags <tt>-static
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| -optl-static</tt> to GHC will avoid problems with missing libraries on
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| the web server.
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|
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| For example, this simple program,
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|
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| <haskell>
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| import Database.SQLite
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| main = print "hey, test this"
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| </haskell>
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|
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| when compiled as $ ghc A.hs --make is dynamically linked against:
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| <haskell>
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| $ ldd A
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| A:
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| Start End Type Open Ref GrpRef Name
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| 0000000000000000 0000000000000000 exe 1 0 0 A
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| 0000000041a85000 0000000041ee5000 rlib 0 1 0 /usr/local/lib/libsqlite3.so.9.0
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| 0000000049b04000 0000000049f1d000 rlib 0 1 0 /usr/lib/libm.so.2.3
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| 0000000042213000 000000004264f000 rlib 0 1 0 /usr/local/lib/libgmp.so.7.0
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| 0000000047d0e000 00000000481e0000 rlib 0 1 0 /usr/lib/libc.so.42.0
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| 0000000047900000 0000000047900000 rtld 0 1 0 /usr/libexec/ld.so
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| </haskell>
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|
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| Now, we can just pass some linker flags through to statically link this lot,
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|
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| <haskell>
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| $ ghc A.hs --make -optl-static -no-recomp
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| $ ldd A
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| ldd: A: not a dynamic executable
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| $ file A
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| A: ELF 64-bit LSB executable, AMD64, version 1, for OpenBSD, statically linked, not stripped
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| </haskell>
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|
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| You could also use the [[Haskell Web Server]].
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|
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| '''Caveats:'''
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|
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| * The <tt>-static</tt> flag in GHC 6.8.2 does not link the libraries in the correct order, resulting in a link failure (which you can hack around if you have to by shuffling <tt>-lpthread</tt> after <tt>-lrt</tt> in the gargantuan linker invocation). This problem should disappear with GHC 6.8.3.
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| * Sometimes you will need to add <tt>extra-libraries</tt> fields to various libraries' <tt>.cabal</tt> files. This manifests as missing symbols. Note that many linkers are sensitive to the order of the <tt>-l</tt> arguments, so the order of libraries in this field matters.
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