Puzzling list comp error: "Don't know how to create ISeq from: clojure.lang.Keyword"
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gvim
Aug 30, 2014, 9:47:20 AM8/30/14
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I have a long function which produces `list-of-lists` :
(("Sun" "21" "li" "13" "201.2139410")
("Moon" "11" "le" "21" "131.3457459")
......)
.... before entering a list comprehension (simplified for brevity):
(defn calc .......
(let [ .....
.......
list-of-lists (map #(rest (first %)) results)]
(for [l list-of-lists
plan (keyword (first l))
deg (Integer/parseInt (second l))
sign (signs (keyword (first (rest (rest l)))))
min (Integer/parseInt (second (rest (rest l))))
long (Float/parseFloat (last l))]
{:deg deg :min min :long long})))
When I call the function I get this error:
IllegalArgumentException Don't know how to create ISeq from:
clojure.lang.Keyword clojure.lang.RT.seqFrom (RT.java:505)
I've tested all the bindings in the repl and they produce the desired
data so it seems the final construction of the map is where the problem
lies.
gvim
(("Sun" "21" "li" "13" "201.2139410")
("Moon" "11" "le" "21" "131.3457459")
......)
.... before entering a list comprehension (simplified for brevity):
(defn calc .......
(let [ .....
.......
list-of-lists (map #(rest (first %)) results)]
(for [l list-of-lists
plan (keyword (first l))
deg (Integer/parseInt (second l))
sign (signs (keyword (first (rest (rest l)))))
min (Integer/parseInt (second (rest (rest l))))
long (Float/parseFloat (last l))]
{:deg deg :min min :long long})))
When I call the function I get this error:
IllegalArgumentException Don't know how to create ISeq from:
clojure.lang.Keyword clojure.lang.RT.seqFrom (RT.java:505)
I've tested all the bindings in the repl and they produce the desired
data so it seems the final construction of the map is where the problem
lies.
gvim
Alexey Kachayev
Aug 30, 2014, 10:07:16 AM8/30/14
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for macro expects each pair to be either binding-form/collection-expr or one of known modifiers (:let, :when, :while).
Here:
plan (keyword (first l))
you give a pair of binding-form and keyword (which is really impossible to iterate over).
If you meant let-binding for plan, dec, min and long, use :let modifier (you can find example in documentation - http://clojuredocs.org/clojure_core/clojure.core/for).
gvim
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gvim
Aug 30, 2014, 11:21:05 AM8/30/14
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On 30/08/2014 15:07, Alexey Kachayev wrote:
> for macro expects each pair to be either binding-form/collection-expr or
> one of known modifiers (:let, :when, :while).
>
> Here:
>
> plan (keyword (first l))
>
> you give a pair of binding-form and keyword (which is really impossible
> to iterate over).
>
> If you meant let-binding for plan, dec, min and long, use :let modifier
> (you can find example in documentation -
> http://clojuredocs.org/clojure_core/clojure.core/for).
>
Yes, of course :) I confused list comp bindings with let bindings. Thanks.
> for macro expects each pair to be either binding-form/collection-expr or
> one of known modifiers (:let, :when, :while).
>
> Here:
>
> plan (keyword (first l))
>
> you give a pair of binding-form and keyword (which is really impossible
> to iterate over).
>
> If you meant let-binding for plan, dec, min and long, use :let modifier
> (you can find example in documentation -
> http://clojuredocs.org/clojure_core/clojure.core/for).
>
gvim
gvim
Aug 30, 2014, 11:49:02 AM8/30/14
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On 30/08/2014 15:07, Alexey Kachayev wrote:
> for macro expects each pair to be either binding-form/collection-expr or
> one of known modifiers (:let, :when, :while).
>
> Here:
>
> plan (keyword (first l))
>
> you give a pair of binding-form and keyword (which is really impossible
> to iterate over).
>
> If you meant let-binding for plan, dec, min and long, use :let modifier
> (you can find example in documentation -
> http://clojuredocs.org/clojure_core/clojure.core/for).
>
I'm going to have to reduce the resulting list next so I thought to use
> one of known modifiers (:let, :when, :while).
>
> Here:
>
> plan (keyword (first l))
>
> you give a pair of binding-form and keyword (which is really impossible
> to iterate over).
>
> If you meant let-binding for plan, dec, min and long, use :let modifier
> (you can find example in documentation -
> http://clojuredocs.org/clojure_core/clojure.core/for).
>
a map version of the list comp. but ran into a similar error:
(defn calc .......
(let [ .....
.......
list-of-lists (map #(rest (first %)) results)]
(map #(let [plan (keyword (first %))
deg (Integer/parseInt (second %))
sign (signs (keyword (first (rest (rest %)))))
min (Integer/parseInt (second (rest (rest %))))
long (Float/parseFloat (last %))]
{plan {:sign sign :deg deg :min min :long long}})))
"Don't know how to create ISeq from: astro.calc$calc$fn__29869"
Now I'm using a let form but the error is similar.
gvim
> <mailto:gvi...@gmail.com>>:
>
> I have a long function which produces `list-of-lists` :
>
> (("Sun" "21" "li" "13" "201.2139410 <tel:201.2139410>")
> I have a long function which produces `list-of-lists` :
>
> Note that posts from new members are moderated - please be patient
> with your first post.
> To unsubscribe from this group, send email to
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>
>
> --
> Kind regards,
> Alexey S. Kachayev,
> CTO at Attendify.com
> ----------
> http://github.com/kachayev
> http://twitter.com/kachayev
> Skype: kachayev
> Tel: +380-996692092
>
>
>
>
> --
> Kind regards,
> Alexey S. Kachayev,
> CTO at Attendify.com
> ----------
> http://github.com/kachayev
> http://twitter.com/kachayev
> Skype: kachayev
> Tel: +380-996692092
>
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Alexey Kachayev
Aug 30, 2014, 12:05:04 PM8/30/14
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Thread-first macro -> will insert list-of-lists as first argument for map, which is definitely not what you expect. Use threading-last ->> instead.
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gvim
Aug 30, 2014, 12:19:31 PM8/30/14
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On 30/08/2014 17:04, Alexey Kachayev wrote:
> Thread-first macro ->will insert list-of-listsas first argument for map,
everything top to bottom and ->> does the reverse. From what you're
saying the choice also affects which position the argument is inserted?
If so this presents a complication in that threading through several
functions may require the argument to be inserted in different positions?
gvim
> Thread-first macro ->will insert list-of-listsas first argument for map,
> which is definitely not what you expect. Use threading-last ->>instead.
>
I've never quite understood the distinction other than -> does
>
everything top to bottom and ->> does the reverse. From what you're
saying the choice also affects which position the argument is inserted?
If so this presents a complication in that threading through several
functions may require the argument to be inserted in different positions?
gvim
Sam Raker
Aug 30, 2014, 1:05:06 PM8/30/14
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`->` inserts its first argument into the second position of the next argument, and so on, so
Turns into
`->>` inserts its first argument into the LAST position of the next argument, and so on, so
Turns into
I guess it is "bottom to top," in a way, but I always thought that was kind of an artifact of the argument (re-)ordering.
(-> []
(conj 1)
(conj 2))Turns into
(conj (conj [] 1) 2)(->> 1
(conj [2])
(conj [3]))
(conj [3] (conj [2] 1))I guess it is "bottom to top," in a way, but I always thought that was kind of an artifact of the argument (re-)ordering.
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