Apply error message

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cameyo
Posts: 109
Joined: Sun Mar 27, 2011 3:07 pm
Location: Italy

Apply error message

Post by cameyo »

The following expression give me an error:

Code: Select all

(apply map list '((a 1) (b 2) (c 3)))
ERR: list expected in function apply : list@4095B0
Instead, I wish the output was:
((a b c) (1 2 3))
Can someone help me?
Thanks

cameyo

Lutz
Posts: 5279
Joined: Thu Sep 26, 2002 4:45 pm
Location: Pasadena, California
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Re: Apply error message

Post by Lutz »

Use transpose:

Code: Select all

> (transpose '((a 1) (b 2) (c 3)))
((a b c) (1 2 3))
> 
A hint will be added to the description of list in the manual.

cameyo
Posts: 109
Joined: Sun Mar 27, 2011 3:07 pm
Location: Italy

Re: Apply error message

Post by cameyo »

"transpose" works like i want :-)
But is the expression wrong logically or syntactically?
Why "apply" does not receive a list?
Thanks again

cameyo

rickyboy
Posts: 595
Joined: Fri Apr 08, 2005 7:13 pm
Location: Front Royal, Virginia

Re: Apply error message

Post by rickyboy »

cameyo wrote:But is the expression wrong logically or syntactically?
Why "apply" does not receive a list?
This is what you had been looking for originally.

Code: Select all

(apply map (cons list '((a 1) (b 2) (c 3))))
(λx. x x) (λx. x x)

cameyo
Posts: 109
Joined: Sun Mar 27, 2011 3:07 pm
Location: Italy

Re: Apply error message

Post by cameyo »

Thanks.
A big help for me.

cameyo

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