Trying to understand tuples and lists

[Hal Daume III]

Based on this and your previous post, I think you're not understanding 
what "<-"/"do" are for.  I think you'll be better off forgetting them 
completely and using 'let/in' for now.

let (x,y) = head [...]
in  ...

is what you want.

On Wed, 5 Nov 2003, Karthik Kumar wrote:

> Hi, 
>     I have a list of  tuples ( characters and numbers ) . 
> 
> say, [('a', 1), ('b', 2)]
> I want to extract 'a' and 1 separately . 
> 
> (x,y) <- head  [('a', 1), ('b', 2)]
> 
>   This doesnt work but my idea is to get x contain the value 'a' and y
> contain the value 1 as the first tuple in the list. 
>    Which is the right way of doing this.  Thanks for your help. 
> 
> Cheers
> Karthik.
> 
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-- 
 Hal Daume III                                   | hdaume at isi.edu
 "Arrest this man, he talks in maths."           | www.isi.edu/~hdaume