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Add compile-time paragraph to manual

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Includes a note in the manual entry for case statements clarifying that the branch values must be known at compile time.
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Zach Smith
2017-12-28 14:10:27 -05:00
committed by Andreas Rumpf
parent 26a34d52a0
commit 3714e2f871
1 changed files with 4 additions and 0 deletions
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doc/manual/stmts.txt
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@@ -296,6 +296,10 @@ empty ``discard`` statement should be used.
For non ordinal types it is not possible to list every possible value and so
these always require an ``else`` part.
As case statements perform compile-time exhaustiveness checks, the value in
every ``of`` branch must be known at compile time. This fact is also exploited
to generate more performant code.
As a special semantic extension, an expression in an ``of`` branch of a case
statement may evaluate to a set or array constructor; the set or array is then
expanded into a list of its elements: