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Very efficient generic functions over arbitrary types.
define-generic[syntax] (define-generic (NAME ARGUMENT ...) BODY ...)
Defines a generic function with the given name, specialized to argument-types as described by ARGUMENT .... ARGUMENT should be either a symbol or a list of the form (TYPE SYMBOL) where a symbol is equivalent to (any SYMBOL).
Calls to NAME textually following this generic definition will be dispatched to the first registered generic with this name that matches the types of the arguments given in the procedure call.
define-type[syntax] (define-type TYPENAME PREDICATE [BASETYPE])
Defines a named type for objects that satisfy PREDICATE (a procedure of one argument that returns either true or false). If BASETYPE is given, it designates the parent type of TYPENAME. Thus types may form a hierarchy. If BASETYPE is not given, any is assumed.
The predicate should be referentially transparent and not cause any side- effects.
The universal base type for objects that satisfy any?, that is, all objects.
- Generic functions can be exported but type-information and -specialization is not visible outside of the current compilation unit or module (if inside a module).
- Calls to generic functions dispatch according to the generic definitions that occur textually before the call, so it is advisable to define all specializations of generic functions first before defining code that calls them.
- Generic functions may not return multiple values and do not accept optional, keyword or rest-arguments.
- All type-dispatching is done at the call-site of a generic function, which provides many opportunities for the compiler to optimize, but may lead to code-bloat if generic functions with long argument lists are used heavily.
The author of the original implementation describes the implementation of an older version of this code in a paper that can be found here.
Thant Tessman, ported to CHICKEN by felix
Copyright (c) Thant Tessman All rights reserved.
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- slight dispatch optimization; basetype argument to define-type wasnÄt quoted
- initial release