diff options
| -rw-r--r-- | share/txr/stdlib/match.tl | 2 | ||||
| -rw-r--r-- | txr.1 | 22 |
2 files changed, 23 insertions, 1 deletions
diff --git a/share/txr/stdlib/match.tl b/share/txr/stdlib/match.tl index d8af1baf..91885472 100644 --- a/share/txr/stdlib/match.tl +++ b/share/txr/stdlib/match.tl @@ -751,7 +751,7 @@ ^(progn (sethash *match-macro* ',name (lambda (,args) - (mac-param-bind ,args + (mac-param-bind *match-form* (,name-dummy ,*destructuring-args) ,args ,*body))) ',name))) @@ -41934,6 +41934,19 @@ The pattern macro bindings are stored in a hash table held by the variable whose keys are symbols, and whose values are expander functions. There are no lexically scoped pattern macros. +If a +.code defmatch +macro uses the +.code :form +parameter to gain access to the form, what the parameter retrieves +is the pattern matching form, or a constituent thereof, in which the +the macro is being invoked. For instance, if the operator is being used +inside a pattern given to a +.code when-match +macro invocation, then the form will be that entire +.code when-match +form. + .TP* Example: .verb @@ -41945,6 +41958,15 @@ There are no lexically scoped pattern macros. ;; use the macro in matching: (when-match @(let x @(or foo bar)) 'foo x) + + ;; Error reporting example using :form + + (defmatch foo (sym) + (unless (bindable sym) + (compile-error *match-form* + "~s: bindable symbol expected, not ~s" + 'foo sym)) + ...) .brev .coNP Special variable @ *match-macro* |