diff options
| author | Jim Fehrle | 2020-08-07 20:54:55 -0700 |
|---|---|---|
| committer | Jim Fehrle | 2020-08-15 22:54:44 -0700 |
| commit | 0e96c241550c4a8abf65f3bb63fcd7cab3380e92 (patch) | |
| tree | de77e762756b319d049e843edb2255c1b47c4b5c /doc | |
| parent | 7427e7c5fa5312e7625ebf5243978691fdb04f92 (diff) | |
Document semantic restriction on patterns
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/sphinx/language/core/variants.rst | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/doc/sphinx/language/core/variants.rst b/doc/sphinx/language/core/variants.rst index d00a2f4100..8e2bf32dd6 100644 --- a/doc/sphinx/language/core/variants.rst +++ b/doc/sphinx/language/core/variants.rst @@ -57,6 +57,11 @@ Private (matching) inductive types Definition by cases: match -------------------------- +Objects of inductive types can be destructured by a case-analysis +construction called *pattern matching* expression. A pattern matching +expression is used to analyze the structure of an inductive object and +to apply specific treatments accordingly. + .. insertprodn term_match pattern0 .. prodn:: @@ -77,10 +82,12 @@ Definition by cases: match | @numeral | @string -Objects of inductive types can be destructured by a case-analysis -construction called *pattern matching* expression. A pattern matching -expression is used to analyze the structure of an inductive object and -to apply specific treatments accordingly. +Note that the :n:`@pattern ::= @pattern10 : @term` production +is not supported in :n:`match` patterns. Trying to use it will give this error: + +.. exn:: Casts are not supported in this pattern. + :undocumented: + This paragraph describes the basic form of pattern matching. See Section :ref:`Mult-match` and Chapter :ref:`extendedpatternmatching` for the description |