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Source for wiki GeneralizedEqualCowan version 1

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cowan

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74.68.121.27

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GeneralizedEqualCowan

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== Generalized `equal?` predicate ==

`(generalized-equal? `''obj1 obj2'' [ ''='' [ ''string=?'' [ ''char=?'' [ ''symbol=?'' [ ''recursive=?'' ] ] ] ] ] `)`

Compares ''obj1'' and ''obj2'' for equality.  If both are pairs, vectors, or bytevectors, or belong to the same implementation-defined container types, returns `#t` if they are equal in length and the same call to `generalized-equal?` returns `#t` on all the components.  If both are numbers, they are compared with the procedure ''=''; if both are characters, they are compared with the procedure ''char=?''; if both are strings, they are compared with the procedure ''string=?''; if both are symbols, they are compared with the procedure ''symbol=?''.  The default values of these are `=`, `char=?`, `string=?`, and `symbol=?` respectively.

In all other cases, the procedure ''recursive=?'' is invoked with three arguments:  ''obj1'', ''obj2'', and a two-argument procedure which returns what `generalized-equal?` returns given the seven arguments passed to or defaulted on it in this call.  This allows ''recursive=?'' to return whatever it likes on atomic types it knows about, and to invoke its third argument on the components of composite types it knows how to descend into.  It is recommended that when ''recursive=?'' receives arguments it does not know how to handle, that it invokes `eqv?` on them.  The default value of ''recursive=?'' always applies `eqv?` to its first two arguments.

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2012-11-29 05:57:49