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| -rw-r--r-- | txr.1 | 86 |
1 files changed, 86 insertions, 0 deletions
@@ -40294,6 +40294,92 @@ if there are no forms. (@x :default)) --> :default .brev +.coNP Macro @ lambda-match +.synb +.mets (lambda-match >> {( pattern << form *)}*) +.syne +.desc +The +.code lambda-match +is closely based on +.codn match-case . + +The arguments of +.code lambda-match +are zero or more clauses similar to those of +.codn match-case . + +An invocation of +.code lambda-match +evaluates to an anonymous function which can take any number of arguments. + +Whenever the function is called, its arguments are treated as a list object +which is subject to pattern matching via the clauses. The +.mets pattern +from every clause is tested against the argument list. If it matches +each associated +.meta form +is evaluated in the scope of the variables emanating from that +.meta pattern +and the value of the last +.meta form +is returned. If no +.meta pattern +matches, the function returns +.codn nil . + +Note: the +.code lambda-macro +can be understood in terms of the following equivalence: + +.verb + (lambda-match ...) <--> (lambda (. rest) (match-case rest ...)) +.brev + +Here, the +.code rest +variable is to be understood as a generated, unique symbol. + +Note: an anonymous function which takes one argument and matches that +object against clauses using +.code match-case +can be obtained with the +.code do +operator, using the pattern: +.codn "(do match @1 ...)" . + +.coNP Macro @ defun-match +.synb +.mets (defun-match < name >> {( pattern << form *)}*) +.syne +.desc +The +.code defun-match +macro can be used to define a top-level function in the style of +.codn lambda-match . + +It works according to the following equivalence: + +.verb + (defun-match name ...) <--> (defun name (. rest) (match-case rest ...)) +.brev + +Here, the +.code rest +variable is to be understood as a generated, unique symbol. + +Because +.code defun-match +is defined in terms of +.codn defun , +it has all of the properties, such as a block of the same +.meta name +being established around the implicit +.code match-case +so that +.code return-from +is possible. + .SS* Quasiquote Operator Syntax .coNP Macro @ qquote .synb |