Difference between revisions of "Performance/Modules"
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== Use an explicit export list == |
== Use an explicit export list == |
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| − | (note: this only applies to compilers based on separate compilation, not to those based on whole-program compilation like [[JHC]]). |
+ | (note: this only applies to compilers based on separate compilation like [[GHC]], not to those based on whole-program compilation like [[JHC]]). |
If you do not have an explicit export list in a module, the compiler must assume that everything in that module will be exported. This disables various useful optimisations: |
If you do not have an explicit export list in a module, the compiler must assume that everything in that module will be exported. This disables various useful optimisations: |
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Revision as of 11:22, 16 January 2006
| Haskell Performance Resource
Constructs: Techniques: |
Use an explicit export list
(note: this only applies to compilers based on separate compilation like GHC, not to those based on whole-program compilation like JHC).
If you do not have an explicit export list in a module, the compiler must assume that everything in that module will be exported. This disables various useful optimisations:
- If a function is used only once in the current module, and not exported, there is no penalty for inlining the function at its single use point.
- If a function is not used at all, and not exported, its definition can be discarded.
- The compiler has more flexibility regarding calling conventions and the like for functions that are not visible beyond the current compilation unit.