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Diffstat (limited to 'docs/users_guide/separate_compilation.rst')
| -rw-r--r-- | docs/users_guide/separate_compilation.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/docs/users_guide/separate_compilation.rst b/docs/users_guide/separate_compilation.rst index ec33cddcd4..c43dcc1f2c 100644 --- a/docs/users_guide/separate_compilation.rst +++ b/docs/users_guide/separate_compilation.rst @@ -705,6 +705,24 @@ beautiful sight! You can read about :ghc-wiki:`how all this works <commentary/compiler/recompilation-avoidance>` in the GHC commentary. +Recompilation for Template Haskell and Plugins +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Recompilation checking gets a bit more complicated when using Template Haskell or +plugins. Both these features execute code at compile time and so if any of the +executed code changes then it's necessary to recompile the module. Consider the +top-level splice:: + + main = $(foo bar [| () |]) + +When the module is compiled ``foo bar [| () |]`` will be evaluated and the resulting +code placed into the program. The dependencies of the expression are calculated +and stored during module compilation. When the interface file is written, additional +dependencies are created on the object file dependencies of the expression. For instance, +if ``foo`` is from module ``A`` and ``bar`` is from module ``B``, the module will +now depend on ``A.o`` and ``B.o``, if either of these change then the module will +be recompiled. + .. _mutual-recursion: How to compile mutually recursive modules |