Re: matching with wild-cards in clojure multi-methods
Hi, On 9 Sep., 21:47, Daniel Werner daniel.d.wer...@googlemail.com wrote: Could this be a bug? No. Clojure does not enforce contracts in several places. Feed wrong things in and get undefined behaviour back. Only the contract is guaranteed. Everything else is an implementation detail and might change at any moment. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: matching with wild-cards in clojure multi-methods
On 9 September 2010 07:31, Meikel Brandmeyer m...@kotka.de wrote: derive works with non-qualified keywords, but the contract disallows that: Apparently the contract given in the docstring is being enforced in derive's 2-arg definition, but the must be namespaced parts of the assertions are missing from the 3-arg definition (the one which takes a custom hierarchy). This difference is quite unexpected. Could this be a bug? -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: matching with wild-cards in clojure multi-methods
On Sep 6, 4:43 pm, Meikel Brandmeyer m...@kotka.de wrote: You can use qualified keywords with an hierarchy. (def your-hierarchy (- (make-hierarchy) (derive ::hello ::anything) (derive ::world ::anything) (derive ::city ::anything) (derive ::us ::anything))) Building your own hierarchy would make it safe to use unqualified keywords as well -- if I am not mistaken? (- (make-hierarchy) (derive :hello :anything) ...) Daniel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: matching with wild-cards in clojure multi-methods
Hi, On 8 Sep., 21:49, Daniel Werner daniel.d.wer...@googlemail.com wrote: Building your own hierarchy would make it safe to use unqualified keywords as well -- if I am not mistaken? (- (make-hierarchy) (derive :hello :anything) ...) derive works with non-qualified keywords, but the contract disallows that: user= (doc derive) - clojure.core/derive ([tag parent] [h tag parent]) Establishes a parent/child relationship between parent and tag. Parent must be a *namespace-qualified* symbol or keyword and child can be either a *namespace-qualified* symbol or keyword or a class. h must be a hierarchy obtained from make-hierarchy, if not supplied defaults to, and modifies, the global hierarchy. (*Emphasis* mine) So: no. You cannot use non-qualified keywords. Even for private hierarchies. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: matching with wild-cards in clojure multi-methods
It looks like the matchure http://github.com/dcolthorp/matchure.git does
this kind of thing .. :) .. I guess somebody has already written a library
to do what I wanted ...
On Mon, Sep 6, 2010 at 9:44 AM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Hi Mark,
Let us say my dispatch function always returns a vector of 4 keywords. now
I want to write my methods in the following way..
(defmethod foo [_ :hello_ _ ] (str I'm method 1))
(defmethod foo [:world _ :us _ ] (str I'm method 2))
(defmethod foo [:city _ :us _ ] (str I'm method 3))
and so on ..
where '_' would match with anything ...
but I just realized I could probably create a type of my own which
overrides the default '=' operator and make it behave like this .. do you
think that would work?
Sunil.
On Mon, Sep 6, 2010 at 9:36 AM, Mark Rathwell mark.rathw...@gmail.comwrote:
Sorry, little slow today. I'm not sure I'm completely following what you
are trying to achieve. What do you want your method prototypes to look
like? (e.g. modify the below to be what you are envisioning):
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
On Sun, Sep 5, 2010 at 11:58 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Thanks Mark for you reply. Well I realized we can do that .. but I feel
it would be more expressive and readable if I could do the wild-card like
pattern matching when I am defining the method.
Sunil.
On Mon, Sep 6, 2010 at 9:25 AM, Mark Rathwell
mark.rathw...@gmail.comwrote:
You can add essentially one more level of indirection to your dispatch
function logic and return an integer (or string or whatever) and match on
that. So, with your example, when you want method1 called, return 1 from
the dispatch function, when you want method2 return 2, you get the idea:
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
...
Is this what you are getting at?
- Mark
On Sun, Sep 5, 2010 at 8:50 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Hello everybody,
It is awesome that we can specify our own dispatch functions and
corresponding values.. However, I feel we should also have control over
the
functions that is used to match the value of the dispatch function with
that
of the one specified in the defmethod.
For instance if my dispatch function is
*(defn mclass [s]*
* (vec (reverse (loop [ret '() val s]*
*(if (coll? val)*
* (recur (cons (class val) ret) (first val))*
* (cons (class val) ret))*
which basically tries to give a list of all the nested types of a
value. If a value is a collection, then all its elements are of same type.
so the above function when applied on .. let us say
*(mclass #{'([1 2] [3 4])*
* '([5 6] [7 8])})*
the return value would be
*[clojure.lang.PersistentHashSet clojure.lang.PersistentList
clojure.lang.PersistentVector java.lang.Integer]*
I would like to despatch based on some pattern of the return value of
my dispatch function *mclass*
*
*
For instance I would like to say something like when the second element
of return value of the dispatch function is *PersistentList call
method1 and call method2 when say the first element is PersistentList and
second element is say PersistentHashSet and call method3 for some
other pattern. Basically a general pattern matching .. So if only I could
have a way of changing how the equality for the purpose of dispatching
behaves .. it would be wonderful. We could either do this or we could
change
the dispatch-val to a dispatch-function with a single argument .. Or is
there a way to already do this?*
In short is it possible to do a generic pattern-matching during
dispatch in multimethods?
Sunil.
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Re: matching with wild-cards in clojure multi-methods
Hi Mark,
Let us say my dispatch function always returns a vector of 4 keywords. now
I want to write my methods in the following way..
(defmethod foo [_ :hello_ _ ] (str I'm method 1))
(defmethod foo [:world _ :us _ ] (str I'm method 2))
(defmethod foo [:city _ :us _ ] (str I'm method 3))
and so on ..
where '_' would match with anything ...
but I just realized I could probably create a type of my own which overrides
the default '=' operator and make it behave like this .. do you think that
would work?
Sunil.
On Mon, Sep 6, 2010 at 9:36 AM, Mark Rathwell mark.rathw...@gmail.comwrote:
Sorry, little slow today. I'm not sure I'm completely following what you
are trying to achieve. What do you want your method prototypes to look
like? (e.g. modify the below to be what you are envisioning):
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
On Sun, Sep 5, 2010 at 11:58 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Thanks Mark for you reply. Well I realized we can do that .. but I feel it
would be more expressive and readable if I could do the wild-card like
pattern matching when I am defining the method.
Sunil.
On Mon, Sep 6, 2010 at 9:25 AM, Mark Rathwell mark.rathw...@gmail.comwrote:
You can add essentially one more level of indirection to your dispatch
function logic and return an integer (or string or whatever) and match on
that. So, with your example, when you want method1 called, return 1 from
the dispatch function, when you want method2 return 2, you get the idea:
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
...
Is this what you are getting at?
- Mark
On Sun, Sep 5, 2010 at 8:50 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Hello everybody,
It is awesome that we can specify our own dispatch functions and
corresponding values.. However, I feel we should also have control over the
functions that is used to match the value of the dispatch function with
that
of the one specified in the defmethod.
For instance if my dispatch function is
*(defn mclass [s]*
* (vec (reverse (loop [ret '() val s]*
*(if (coll? val)*
* (recur (cons (class val) ret) (first val))*
* (cons (class val) ret))*
which basically tries to give a list of all the nested types of a
value. If a value is a collection, then all its elements are of same type.
so the above function when applied on .. let us say
*(mclass #{'([1 2] [3 4])*
* '([5 6] [7 8])})*
the return value would be
*[clojure.lang.PersistentHashSet clojure.lang.PersistentList
clojure.lang.PersistentVector java.lang.Integer]*
I would like to despatch based on some pattern of the return value of my
dispatch function *mclass*
*
*
For instance I would like to say something like when the second element
of return value of the dispatch function is *PersistentList call
method1 and call method2 when say the first element is PersistentList and
second element is say PersistentHashSet and call method3 for some
other pattern. Basically a general pattern matching .. So if only I could
have a way of changing how the equality for the purpose of dispatching
behaves .. it would be wonderful. We could either do this or we could
change
the dispatch-val to a dispatch-function with a single argument .. Or is
there a way to already do this?*
In short is it possible to do a generic pattern-matching during dispatch
in multimethods?
Sunil.
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Re: matching with wild-cards in clojure multi-methods
Thanks Mark for you reply. Well I realized we can do that .. but I feel it
would be more expressive and readable if I could do the wild-card like
pattern matching when I am defining the method.
Sunil.
On Mon, Sep 6, 2010 at 9:25 AM, Mark Rathwell mark.rathw...@gmail.comwrote:
You can add essentially one more level of indirection to your dispatch
function logic and return an integer (or string or whatever) and match on
that. So, with your example, when you want method1 called, return 1 from
the dispatch function, when you want method2 return 2, you get the idea:
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
...
Is this what you are getting at?
- Mark
On Sun, Sep 5, 2010 at 8:50 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Hello everybody,
It is awesome that we can specify our own dispatch functions and
corresponding values.. However, I feel we should also have control over the
functions that is used to match the value of the dispatch function with that
of the one specified in the defmethod.
For instance if my dispatch function is
*(defn mclass [s]*
* (vec (reverse (loop [ret '() val s]*
*(if (coll? val)*
* (recur (cons (class val) ret) (first val))*
* (cons (class val) ret))*
which basically tries to give a list of all the nested types of a value.
If a value is a collection, then all its elements are of same type.
so the above function when applied on .. let us say
*(mclass #{'([1 2] [3 4])*
* '([5 6] [7 8])})*
the return value would be
*[clojure.lang.PersistentHashSet clojure.lang.PersistentList
clojure.lang.PersistentVector java.lang.Integer]*
I would like to despatch based on some pattern of the return value of my
dispatch function *mclass*
*
*
For instance I would like to say something like when the second element of
return value of the dispatch function is *PersistentList call method1
and call method2 when say the first element is PersistentList and second
element is say PersistentHashSet and call method3 for some other
pattern. Basically a general pattern matching .. So if only I could have a
way of changing how the equality for the purpose of dispatching behaves ..
it would be wonderful. We could either do this or we could change the
dispatch-val to a dispatch-function with a single argument .. Or is there a
way to already do this?*
In short is it possible to do a generic pattern-matching during dispatch
in multimethods?
Sunil.
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Re: matching with wild-cards in clojure multi-methods
Hi, On 6 Sep., 06:14, Sunil S Nandihalli sunil.nandiha...@gmail.com wrote: (defmethod foo [_ :hello _ _ ] (str I'm method 1)) (defmethod foo [:world _ :us _ ] (str I'm method 2)) (defmethod foo [:city _ :us _ ] (str I'm method 3)) You can use qualified keywords with an hierarchy. (def your-hierarchy (- (make-hierarchy) (derive ::hello ::anything) (derive ::world ::anything) (derive ::city ::anything) (derive ::us ::anything))) (defmulti foo your-dispatch-fn-here :hierarchy your-hierarchy) (defmethod foo [::anything ::hello ::anything ::anything] (str I'm method 1)) (defmethod foo [::world::anything ::us ::anything] (str I'm method 2)) (defmethod foo [::city ::anything ::us ::anything] (str I'm method 3)) Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
Re: matching with wild-cards in clojure multi-methods
thanks Meikel for the suggestion .. I never thought of that .. (or actually didn't know about it).. I think that helps.. Sunil. On Mon, Sep 6, 2010 at 8:19 PM, Meikel Brandmeyer m...@kotka.de wrote: Hi, On 6 Sep., 16:43, Meikel Brandmeyer m...@kotka.de wrote: (defmulti foo your-dispatch-fn-here :hierarchy your-hierarchy) Woops. You should use an atom for the hierarchy or use the Var in the call above: #'your-hierarchy. An atom would allow later modification of the hierarchy. Sincerely Meikel -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.comclojure%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -- You received this message because you are subscribed to the Google Groups Clojure group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en
matching with wild-cards in clojure multi-methods
Hello everybody,
It is awesome that we can specify our own dispatch functions and
corresponding values.. However, I feel we should also have control over the
functions that is used to match the value of the dispatch function with that
of the one specified in the defmethod.
For instance if my dispatch function is
*(defn mclass [s]*
* (vec (reverse (loop [ret '() val s]*
*(if (coll? val)*
* (recur (cons (class val) ret) (first val))*
* (cons (class val) ret))*
which basically tries to give a list of all the nested types of a value. If
a value is a collection, then all its elements are of same type.
so the above function when applied on .. let us say
*(mclass #{'([1 2] [3 4])*
* '([5 6] [7 8])})*
the return value would be
*[clojure.lang.PersistentHashSet clojure.lang.PersistentList
clojure.lang.PersistentVector java.lang.Integer]*
I would like to despatch based on some pattern of the return value of my
dispatch function *mclass*
*
*
For instance I would like to say something like when the second element of
return value of the dispatch function is *PersistentList call method1 and
call method2 when say the first element is PersistentList and second element
is say PersistentHashSet and call method3 for some other pattern. Basically
a general pattern matching .. So if only I could have a way of changing how
the equality for the purpose of dispatching behaves .. it would be
wonderful. We could either do this or we could change the dispatch-val to a
dispatch-function with a single argument .. Or is there a way to already do
this?*
In short is it possible to do a generic pattern-matching during dispatch in
multimethods?
Sunil.
--
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Re: matching with wild-cards in clojure multi-methods
You can add essentially one more level of indirection to your dispatch
function logic and return an integer (or string or whatever) and match on
that. So, with your example, when you want method1 called, return 1 from
the dispatch function, when you want method2 return 2, you get the idea:
(defmulti foo mclass)
(defmethod foo 1 [s] (str I'm method 1))
(defmethod foo 2 [s] (str I'm method 2))
...
Is this what you are getting at?
- Mark
On Sun, Sep 5, 2010 at 8:50 PM, Sunil S Nandihalli
sunil.nandiha...@gmail.com wrote:
Hello everybody,
It is awesome that we can specify our own dispatch functions and
corresponding values.. However, I feel we should also have control over the
functions that is used to match the value of the dispatch function with that
of the one specified in the defmethod.
For instance if my dispatch function is
*(defn mclass [s]*
* (vec (reverse (loop [ret '() val s]*
*(if (coll? val)*
* (recur (cons (class val) ret) (first val))*
* (cons (class val) ret))*
which basically tries to give a list of all the nested types of a value.
If a value is a collection, then all its elements are of same type.
so the above function when applied on .. let us say
*(mclass #{'([1 2] [3 4])*
* '([5 6] [7 8])})*
the return value would be
*[clojure.lang.PersistentHashSet clojure.lang.PersistentList
clojure.lang.PersistentVector java.lang.Integer]*
I would like to despatch based on some pattern of the return value of my
dispatch function *mclass*
*
*
For instance I would like to say something like when the second element of
return value of the dispatch function is *PersistentList call method1 and
call method2 when say the first element is PersistentList and second
element is say PersistentHashSet and call method3 for some other pattern.
Basically a general pattern matching .. So if only I could have a way of
changing how the equality for the purpose of dispatching behaves .. it would
be wonderful. We could either do this or we could change the dispatch-val to
a dispatch-function with a single argument .. Or is there a way to already
do this?*
In short is it possible to do a generic pattern-matching during dispatch in
multimethods?
Sunil.
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