anon func syntax confusion

[László Török]

Hi,

just a quick one:

(mapcat #([% 1]) [1 3 5])

gives an exception (wrong argument)

(mapcat (fn [a] [a 1]) [1 3 5])

works though...

What did I get wrong?

Thx

Las

[Meikel Brandmeyer]

Hi,

#([% 1]) is equivalent to (fn [a] ([a 1])). Note the extra parens. You
want #(vector % 1).

Sincerely
Meikel

[Nick Zbinden]

That a problem people find often.

The thing is #(%) not the same as (fn [x] x) its more like (fn [x]
(x)).

So if you write #([x]) is (fn [x] ([x])) witch throws an error. You
would have to write #(vec %).

[Karl Ward]

On Monday, January 24, 2011 12:59:09 PM UTC, Las wrote:

What did I get wrong?

I believe #([% 1]) is equivalent to (fn [a] ([a 1])), not (fn [a] [a 1]) . Thus, for #([% 1]) , [% 1] is called as a function. Vectors are functions that take an index and return the vector's value at that index.

[László Török]

Thanks! :)

2011/1/24 Nick Zbinden <nic...@gmail.com>

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