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| author | Joey Hess <joeyh@joeyh.name> | 2016-03-08 17:54:49 -0400 |
|---|---|---|
| committer | Joey Hess <joeyh@joeyh.name> | 2016-03-08 17:54:49 -0400 |
| commit | 61a1ba8ff1fa496af24d22986057a7607ae55ff1 (patch) | |
| tree | a8ceb1621f4f2cf74892bcec2977dc72135df851 /doc | |
| parent | 4dab5fd328fc04ed006f32014330dac2621f0385 (diff) | |
make it a type error to intersect two OS lists if the result is empty
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/todo/type_level_OS_requirements.mdwn | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/doc/todo/type_level_OS_requirements.mdwn b/doc/todo/type_level_OS_requirements.mdwn index 65e6099f..6d5d7aaf 100644 --- a/doc/todo/type_level_OS_requirements.mdwn +++ b/doc/todo/type_level_OS_requirements.mdwn @@ -11,7 +11,9 @@ For example, `Property i '[Debian, FreeBSD]` combined with `Property i '[Debian, yields a `Property i '[Debian]` -- the intersection of the OS's supported by the combined properties. -And, combining two properties that demand different OS's would need to be a +Combining two properties that demand different OS's would yield a +`Property i '[]` -- since the type level OS list is empty, + type error. Can a type level function combine two types successfully, and fail to combine two others somehow? Don't know. Maybe combine to an IncoherentOS and don't allow a `Property i IncoherentOS` to be used in a |