Generic versions of commonly used functions, implemented as multimethods that can be implemented for any data type.
Each submodule of clojure.algo.generic defines a set of related multimethods that have the same names as their type-specific counterparts in clojure.core. Implementations for standard Clojure data types are provided and behave identically to the clojure.core versions.
Arithmetic and comparison functions are defined for the same arities
that the corresponding clojure.core functions support. Arities higher
than 2 are reduced to unary and binary calls. To provide a multimethod
implementation for binary calls with a given pair of types, use
[type1 type2] as the dispatch value. For a unary call, the dispatch
type as usual. Note that
[type1 type2] is different from
[type2 type1] (in most cases you will want to provide both) and that
[type type] (binary operation with both arguments of the same type)
is different from
type (unary operation).
This section applies only to binary operations dispatching on type
pairs, and only for types that are not Java classes. Types
defrecord are Java classes, meaning that
most Clojure programmers can go on with the next section.
One difficulty with binary operations is that there is no predefined
way to provide a default implementation. For single dispatch there is
:default, but there is nothing equivalent to
The algo.generic library therefore defines a root type, accessible
clojure.algo.generic/root-type, which is used in the default
implementations of binary operations. To integrate your own type into
this system, you must add the clause
clojure.algo.generic/root-type) after your type definition. This is
not required for Java classes because
already derived from
algo.generic.arithmetic provides generic
/for all the arities that the corresponding clojure.core functions support. The minimal implementations required for full arithmetic on a given type is binary
/. You may wish to provide explicit implementations for binary
/for efficiency, otherwise the default implementations are
(- a b) => (+ a (- b))and
(/ a b) => (* a (/ b)).
algo.generic.collection provides generic versions of
intohas a default implementation in terms of
seq, but you may wish to provide a more efficient one for your types.
algo.generic.comparison provides the comparison and test functions
maxcannot be redefined, they are standard functions that are implemented in terms of the generic functions of the module. A minimal implementation of the binary comparison functions consists of
>. Default implementations for
>, but more efficient implementations can be provided.
algo.generic.math-functions provides generic versions of the common math functions from
Copyright (c) Rich Hickey and contributors. All rights reserved.
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