Re: Problems with map of empty collections
I'd also like to know if there is a way to construct a Map or Set that
differentiates lists and vectors.
To try to answer your question, Juan, I think it's because of the
`clojure.core/=` semantics. From the docstring: compares numbers and
collections in a type-independent manner. So,
user (= () [])
true
user (= (list 1 2 3) (vector 1 2 3))
true
And even nested sequence-like things:
user (= [1 [2 3]] '(1 (2 3)))
true
In addition, they even hash to the same value:
user (map hash [ () [] '(1) [1] ])
(1 1 32 32)
It's probably that last property that causes the weird behavior for maps
and sets.
--Leif
On Tuesday, April 3, 2012 12:11:50 AM UTC-7, JuanManuel Gimeno Illa wrote:
Playing with some problems of 4clojure, I wanted to make a map which, for
each empty collection, returns a keyword. But it seems that it is
impossible to have both an empty list and an empty vector in the same map.
user= {() :list}
{() :list}
user= {() :list [] :vector}
IllegalArgumentException Duplicate key:
clojure.lang.PersistentList$EmptyList@1
clojure.lang.PersistentArrayMap.createWithCheck
(PersistentArrayMap.java:70)
user= {[] :vector}
{[] :vector}
I supposed that this is due to (= [] ()) but
user= {'(1) :list [1] :vector}
{(1) :vector}
user= (= [1]'(1))
true
What am I missing?
Juan Manuel
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Problems with map of empty collections
Playing with some problems of 4clojure, I wanted to make a map which, for
each empty collection, returns a keyword. But it seems that it is
impossible to have both an empty list and an empty vector in the same map.
user= {() :list}
{() :list}
user= {() :list [] :vector}
IllegalArgumentException Duplicate key:
clojure.lang.PersistentList$EmptyList@1
clojure.lang.PersistentArrayMap.createWithCheck
(PersistentArrayMap.java:70)
user= {[] :vector}
{[] :vector}
I supposed that this is due to (= [] ()) but
user= {'(1) :list [1] :vector}
{(1) :vector}
user= (= [1]'(1))
true
What am I missing?
Juan Manuel
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Re: Problems with map of empty collections
Another interesting fact is that:
Clojure 1.2.1
user= {'(1) :list [1] :vector}
java.lang.IllegalArgumentException: Duplicate key: (1) (NO_SOURCE_FILE:0)
Clojure 1.3.0
user= {'(1) :list [1] :vector}
{(1) :vector}
Clojure 1.4.0-beta1
user= {'(1) :list [1] :vector}
{(1) :vector}
...but I don't know what's going on.
On Tuesday, April 3, 2012 9:11:50 AM UTC+2, JuanManuel Gimeno Illa wrote:
Playing with some problems of 4clojure, I wanted to make a map which, for
each empty collection, returns a keyword. But it seems that it is
impossible to have both an empty list and an empty vector in the same map.
user= {() :list}
{() :list}
user= {() :list [] :vector}
IllegalArgumentException Duplicate key:
clojure.lang.PersistentList$EmptyList@1
clojure.lang.PersistentArrayMap.createWithCheck
(PersistentArrayMap.java:70)
user= {[] :vector}
{[] :vector}
I supposed that this is due to (= [] ()) but
user= {'(1) :list [1] :vector}
{(1) :vector}
user= (= [1]'(1))
true
What am I missing?
Juan Manuel
--
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Re: Problems with map of empty collections
More examples in clojure 1.3.0:
user= {[1 2 3] :vector '(1 2 3) :list}
{[1 2 3] :list}
but
user= #{[1 2 3] (1 2 3)}
IllegalArgumentException Duplicate key: (1 2 3)
clojure.lang.PersistentHashSet.createWithCheck (PersistentHashSet.java:68)
... anyone has an explanation?
Juan Manuel
On Tuesday, April 3, 2012 10:55:26 AM UTC+2, mnicky wrote:
Another interesting fact is that:
Clojure 1.2.1
user= {'(1) :list [1] :vector}
java.lang.IllegalArgumentException: Duplicate key: (1) (NO_SOURCE_FILE:0)
Clojure 1.3.0
user= {'(1) :list [1] :vector}
{(1) :vector}
Clojure 1.4.0-beta1
user= {'(1) :list [1] :vector}
{(1) :vector}
...but I don't know what's going on.
On Tuesday, April 3, 2012 9:11:50 AM UTC+2, JuanManuel Gimeno Illa wrote:
Playing with some problems of 4clojure, I wanted to make a map which, for
each empty collection, returns a keyword. But it seems that it is
impossible to have both an empty list and an empty vector in the same map.
user= {() :list}
{() :list}
user= {() :list [] :vector}
IllegalArgumentException Duplicate key:
clojure.lang.PersistentList$EmptyList@1
clojure.lang.PersistentArrayMap.createWithCheck
(PersistentArrayMap.java:70)
user= {[] :vector}
{[] :vector}
I supposed that this is due to (= [] ()) but
user= {'(1) :list [1] :vector}
{(1) :vector}
user= (= [1]'(1))
true
What am I missing?
Juan Manuel
--
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Re: Problems with map of empty collections
I think quoting plays a part here:
Clojure 1.3.0
user= {(list 1 2 3) :list [1 2 3] :vec}
IllegalArgumentException Duplicate key: (1 2 3)
clojure.lang.PersistentArrayMap.createWithCheck (PersistentArrayMap.java:70)
Stuart
On 3 April 2012 22:41, JuanManuel Gimeno Illa jmgim...@gmail.com wrote:
More examples in clojure 1.3.0:
user= {[1 2 3] :vector '(1 2 3) :list}
{[1 2 3] :list}
but
user= #{[1 2 3] (1 2 3)}
IllegalArgumentException Duplicate key: (1 2 3)
clojure.lang.PersistentHashSet.createWithCheck (PersistentHashSet.java:68)
... anyone has an explanation?
Juan Manuel
On Tuesday, April 3, 2012 10:55:26 AM UTC+2, mnicky wrote:
Another interesting fact is that:
Clojure 1.2.1
user= {'(1) :list [1] :vector}
java.lang.**IllegalArgumentException: Duplicate key: (1)
(NO_SOURCE_FILE:0)
Clojure 1.3.0
user= {'(1) :list [1] :vector}
{(1) :vector}
Clojure 1.4.0-beta1
user= {'(1) :list [1] :vector}
{(1) :vector}
...but I don't know what's going on.
On Tuesday, April 3, 2012 9:11:50 AM UTC+2, JuanManuel Gimeno Illa wrote:
Playing with some problems of 4clojure, I wanted to make a map which,
for each empty collection, returns a keyword. But it seems that it is
impossible to have both an empty list and an empty vector in the same map.
user= {() :list}
{() :list}
user= {() :list [] :vector}
IllegalArgumentException Duplicate key: clojure.lang.PersistentList$**
EmptyList@1 clojure.lang.**PersistentArrayMap.**createWithCheck
(PersistentArrayMap.java:70)
user= {[] :vector}
{[] :vector}
I supposed that this is due to (= [] ()) but
user= {'(1) :list [1] :vector}
{(1) :vector}
user= (= [1]'(1))
true
What am I missing?
Juan Manuel
--
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