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Merge pull request #1842 from Kodiologist/rm-multi

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Remove hy.contrib.multi
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Ryan Gonzalez 2019-11-19 19:38:54 -06:00 committed by GitHub
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2
NEWS.rst
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@ -10,6 +10,8 @@ Removals
and `defn` instead.
* Literal keywords are no longer parsed differently in calls to functions
with certain names.
* `hy.contrib.multi` has been removed. Use ``cond`` or the PyPI package
``multipledispatch`` instead.
New Features
------------------------------

1
docs/contrib/index.rst
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@ -12,7 +12,6 @@ Contents:
:maxdepth: 3
loop
multi
profile
sequences
walk

110
docs/contrib/multi.rst
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@ -1,110 +0,0 @@
========
defmulti
========
defn
----
.. versionadded:: 0.10.0
``defn`` lets you arity-overload a function by the given number of
args and/or kwargs. This version of ``defn`` works with regular syntax and
with the arity overloaded one. Inspired by Clojures take on ``defn``.
.. code-block:: clj
=> (require [hy.contrib.multi [defn]])
=> (defn fun
... ([a] "a")
... ([a b] "a b")
... ([a b c] "a b c"))
=> (fun 1)
"a"
=> (fun 1 2)
"a b"
=> (fun 1 2 3)
"a b c"
=> (defn add [a b]
... (+ a b))
=> (add 1 2)
3
defmulti
--------
.. versionadded:: 0.12.0
``defmulti``, ``defmethod`` and ``default-method`` lets you define
multimethods where a dispatching function is used to select between different
implementations of the function. Inspired by Clojure's multimethod and based
on the code by `Adam Bard`_.
.. code-block:: clj
=> (require [hy.contrib.multi [defmulti defmethod default-method]])
=> (defmulti area [shape]
... "calculate area of a shape"
... (:type shape))
=> (defmethod area "square" [square]
... (* (:width square)
... (:height square)))
=> (defmethod area "circle" [circle]
... (* (** (:radius circle) 2)
... 3.14))
=> (default-method area [shape]
... 0)
=> (area {:type "circle" :radius 0.5})
0.785
=> (area {:type "square" :width 2 :height 2})
4
=> (area {:type "non-euclid rhomboid"})
0
``defmulti`` is used to define the initial multimethod with name, signature
and code that selects between different implementations. In the example,
multimethod expects a single input that is type of dictionary and contains
at least key :type. The value that corresponds to this key is returned and
is used to selected between different implementations.
``defmethod`` defines a possible implementation for multimethod. It works
otherwise in the same way as ``defn``, but has an extra parameters
for specifying multimethod and which calls are routed to this specific
implementation. In the example, shapes with "square" as :type are routed to
first function and shapes with "circle" as :type are routed to second
function.
``default-method`` specifies default implementation for multimethod that is
called when no other implementation matches.
Interfaces of multimethod and different implementation don't have to be
exactly identical, as long as they're compatible enough. In practice this
means that multimethod should accept the broadest range of parameters and
different implementations can narrow them down.
.. code-block:: clj
=> (require [hy.contrib.multi [defmulti defmethod]])
=> (defmulti fun [&rest args]
... (len args))
=> (defmethod fun 1 [a]
... a)
=> (defmethod fun 2 [a b]
... (+ a b))
=> (fun 1)
1
=> (fun 1 2)
3
.. _Adam Bard: https://adambard.com/blog/implementing-multimethods-in-python/

89
hy/contrib/multi.hy
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@ -1,89 +0,0 @@
;; Hy Arity-overloading
;; Copyright 2019 the authors.
;; This file is part of Hy, which is free software licensed under the Expat
;; license. See the LICENSE.
(import [collections [defaultdict]]
[hy [HyExpression HyList HyString]])
(defclass MultiDispatch [object]
(setv _fns (defaultdict dict))
(defn __init__ [self f]
(setv self.f f)
(setv self.__doc__ f.__doc__)
(unless (in f.__name__ (.keys (get self._fns f.__module__)))
(setv (get self._fns f.__module__ f.__name__) {}))
(setv values f.__code__.co_varnames)
(setv (get self._fns f.__module__ f.__name__ values) f))
(defn fn? [self v args kwargs]
"Compare the given (checked fn) to the called fn"
(setv com (+ (list args) (list (.keys kwargs))))
(and
(= (len com) (len v))
(.issubset (frozenset (.keys kwargs)) com)))
(defn __call__ [self &rest args &kwargs kwargs]
(setv func None)
(for [[i f] (.items (get self._fns self.f.__module__ self.f.__name__))]
(when (.fn? self i args kwargs)
(setv func f)
(break)))
(if func
(func #* args #** kwargs)
(raise (TypeError "No matching functions with this signature")))))
(defn multi-decorator [dispatch-fn]
(setv inner (fn [&rest args &kwargs kwargs]
(setv dispatch-key (dispatch-fn #* args #** kwargs))
(if (in dispatch-key inner.--multi--)
((get inner.--multi-- dispatch-key) #* args #** kwargs)
(inner.--multi-default-- #* args #** kwargs))))
(setv inner.--multi-- {})
(setv inner.--doc-- dispatch-fn.--doc--)
(setv inner.--multi-default-- (fn [&rest args &kwargs kwargs] None))
inner)
(defn method-decorator [dispatch-fn &optional [dispatch-key None]]
(setv apply-decorator
(fn [func]
(if (is dispatch-key None)
(setv dispatch-fn.--multi-default-- func)
(assoc dispatch-fn.--multi-- dispatch-key func))
dispatch-fn))
apply-decorator)
(defmacro defmulti [name params &rest body]
`(do (import [hy.contrib.multi [multi-decorator]])
(with-decorator multi-decorator
(defn ~name ~params ~@body))))
(defmacro defmethod [name multi-key params &rest body]
`(do (import [hy.contrib.multi [method-decorator]])
(with-decorator (method-decorator ~name ~multi-key)
(defn ~name ~params ~@body))))
(defmacro default-method [name params &rest body]
`(do (import [hy.contrib.multi [method-decorator]])
(with-decorator (method-decorator ~name)
(defn ~name ~params ~@body))))
(defmacro defn [name &rest bodies]
(setv arity-overloaded? (fn [bodies]
(if (isinstance (first bodies) HyString)
(arity-overloaded? (rest bodies))
(isinstance (first bodies) HyExpression))))
(if (arity-overloaded? bodies)
(do
(setv comment (HyString))
(if (= (type (first bodies)) HyString)
(setv [comment #* bodies] bodies))
(+ '(do (import [hy.contrib.multi [MultiDispatch]])) (lfor
[let-binds #* body] bodies
`(with-decorator MultiDispatch (defn ~name ~let-binds ~comment ~@body)))))
(do
(setv [lambda-list #* body] bodies)
`(setv ~name (fn* ~lambda-list ~@body)))))

123
tests/native_tests/contrib/multi.hy
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@ -1,123 +0,0 @@
;; Copyright 2019 the authors.
;; This file is part of Hy, which is free software licensed under the Expat
;; license. See the LICENSE.
(require [hy.contrib.multi [defmulti defmethod default-method defn]])
(import pytest)
(defn test-different-signatures []
"NATIVE: Test multimethods with different signatures"
(defmulti fun [&rest args]
(len args))
(defmethod fun 0 []
"Hello!")
(defmethod fun 1 [a]
a)
(defmethod fun 2 [a b]
"a b")
(defmethod fun 3 [a b c]
"a b c")
(assert (= (fun) "Hello!"))
(assert (= (fun "a") "a"))
(assert (= (fun "a" "b") "a b"))
(assert (= (fun "a" "b" "c") "a b c")))
(defn test-different-signatures-defn []
"NATIVE: Test defn with different signatures"
(defn f1
([] "")
([a] "a")
([a b] "a b"))
(assert (= (f1) ""))
(assert (= (f1 "a") "a"))
(assert (= (f1 "a" "b") "a b"))
(with [(pytest.raises TypeError)]
(f1 "a" "b" "c")))
(defn test-basic-dispatch []
"NATIVE: Test basic dispatch"
(defmulti area [shape]
(:type shape))
(defmethod area "square" [square]
(* (:width square)
(:height square)))
(defmethod area "circle" [circle]
(* (** (:radius circle) 2)
3.14))
(default-method area [shape]
0)
(assert (< 0.784 (area {:type "circle" :radius 0.5}) 0.786))
(assert (= (area {:type "square" :width 2 :height 2})) 4)
(assert (= (area {:type "non-euclid rhomboid"}) 0)))
(defn test-docs []
"NATIVE: Test if docs are properly handled"
(defmulti fun [a b]
"docs"
a)
(defmethod fun "foo" [a b]
"foo was called")
(defmethod fun "bar" [a b]
"bar was called")
(assert (= fun.--doc-- "docs")))
(defn test-kwargs-handling []
"NATIVE: Test handling of kwargs with multimethods"
(defmulti fun [&kwargs kwargs]
(get kwargs "type"))
(defmethod fun "foo" [&kwargs kwargs]
"foo was called")
(defmethod fun "bar" [&kwargs kwargs]
"bar was called")
(assert (= (fun :type "foo" :extra "extra") "foo was called")))
(defn test-basic-multi []
"NATIVE: Test a basic arity overloaded defn"
(defn f2
([] "Hello!")
([a] a)
([a b] "a b")
([a b c] "a b c"))
(assert (= (f2) "Hello!"))
(assert (= (f2 "a") "a"))
(assert (= (f2 "a" "b") "a b"))
(assert (= (f2 "a" "b" "c") "a b c")))
(defn test-kw-args []
"NATIVE: Test if kwargs are handled correctly for arity overloading"
(defn f3
([a] a)
([&optional [a "nop"] [b "p"]] (+ a b)))
(assert (= (f3 1) 1))
(assert (= (f3 :a "t") "t"))
(assert (= (f3 "hello " :b "world") "hello world"))
(assert (= (f3 :a "hello " :b "world") "hello world")))
(defn test-docs []
"NATIVE: Test if docs are properly handled for arity overloading"
(defn f4
"docs"
([a] (print a))
([a b] (print b)))
(assert (= f4.--doc-- "docs")))