diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 36 |
1 files changed, 33 insertions, 3 deletions
@@ -40001,7 +40001,24 @@ which may be trivial or non-trivial. If .meta key-pattern -is a non-trivial pattern, but +is a simple variable pattern +.mono +.meti >> @ sym +.onom +and if +.meta sym +has an existing binding, then the value of +.meta sym +is looked up in the hash table. If it is not found, then +the match fails, otherwise the corresponding value is matched +against +.metn value-pattern , +which may be trivial or non-trivial. + +If +.meta key-pattern +is a non-trivial pattern other than a variable pattern +for a variable which has an existing binding, and if .meta value-pattern is trivial, then .meta value-pattern @@ -40056,11 +40073,24 @@ operator matching against an association list. ;; First, (x @y) has a trivial key pattern so the x ;; entry from the hash table is retrieved, the ;; value being the symbol k. This k is bound to @y. - ;; Then the pattern (@y @datum) searches the entire + ;; Because y now a bound variable the pattern (@y @datum) + ;; is interpreted as search of the hash table for + ;; a single entry matching the value of @y. This + ;; is the k entry, whose value is 42. The @datum + ;; value match takes this 42. + (when-match @(hash (x @y) (@y @datum)) #H(() (x k) (k 42)) datum) + --> 42 + + ;; Again, (x @y) has a trivial key pattern so the x + ;; entry from the hash table is retrieved, the + ;; value being the symbol k. This k is bound to @y. + ;; This time the second pattern has a @(symbolp) + ;; predicate operator. This is not a variable, and + ;; so the pattern searches the entire ;; hash table. The @y variable has a binding to k, ;; so only the (k 42) entry is matched. The 42 ;; value matches @datum, and is collected into a list. - (when-match @(hash (x @y) (@y @datum)) #H(() (x k) (k 42)) datum) + (when-match @(hash (x @y) (@(symbolp y) @datum)) #H(() (x k) (k 42)) datum) --> (42) .brev |