diff options
Diffstat (limited to 'doc/sphinx/language')
| -rw-r--r-- | doc/sphinx/language/core/inductive.rst | 6 | ||||
| -rw-r--r-- | doc/sphinx/language/extensions/match.rst | 37 |
2 files changed, 40 insertions, 3 deletions
diff --git a/doc/sphinx/language/core/inductive.rst b/doc/sphinx/language/core/inductive.rst index 122b0f5dfb..ba0ec28f8b 100644 --- a/doc/sphinx/language/core/inductive.rst +++ b/doc/sphinx/language/core/inductive.rst @@ -342,9 +342,9 @@ Recursive functions: fix .. insertprodn term_fix fixannot .. prodn:: - term_fix ::= let fix @fix_body in @term - | fix @fix_body {? {+ with @fix_body } for @ident } - fix_body ::= @ident {* @binder } {? @fixannot } {? : @type } := @term + term_fix ::= let fix @fix_decl in @term + | fix @fix_decl {? {+ with @fix_decl } for @ident } + fix_decl ::= @ident {* @binder } {? @fixannot } {? : @type } := @term fixannot ::= %{ struct @ident %} | %{ wf @one_term @ident %} | %{ measure @one_term {? @ident } {? @one_term } %} diff --git a/doc/sphinx/language/extensions/match.rst b/doc/sphinx/language/extensions/match.rst index 561262262b..3c1983ee97 100644 --- a/doc/sphinx/language/extensions/match.rst +++ b/doc/sphinx/language/extensions/match.rst @@ -290,6 +290,43 @@ This example emphasizes what the printing settings offer. Print snd. +Conventions about unused pattern-matching variables +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Pattern-matching variables that are not used on the right-hand side of ``=>`` are +considered the sign of a potential error. For instance, it could +result from an undetected mispelled constant constructor. By default, +a warning is issued in such situations. + +.. warn:: Unused variable @ident catches more than one case. + + This indicates that an unused pattern variable :token:`ident` + occurs in a pattern-matching clause used to complete at least two + cases of the pattern-matching problem. + + The warning can be deactivated by using a variable name starting + with ``_`` or by setting ``Set Warnings + "-unused-pattern-matching-variable"``. + + Here is an example where the warning is activated. + + .. example:: + + .. coqtop:: none + + Set Warnings "-unused-pattern-matching-variable". + + .. coqtop:: all + + Definition is_zero (o : option nat) := match o with + | Some 0 => true + | x => false + end. + + .. coqtop:: none + + Set Warnings "+unused-pattern-matching-variable". + Patterns -------- |