optimization ?

[Ingela Anderton]

Bengt Kleberg wrote:
> 
> > Date: Tue, 22 Apr 2003 01:09:11 -0500
> > From: Chris Pressey <cpressey@REDACTED>
> > Subject: Re: optimization ?
> ...deleted
> > expensive compared to a simple cons.  You might want to try [T|Acc]...
> > 
> > > 	    end;	
> > > 	Other -> 
> > > 	    dirs(Top, Tail, Acc)
> > >     end;
> > > 
> > > dirs(_Top, [], Ack) -> Ack.
> > 
> > ...then lists:flatten/1 the result here before you return it, if you
> 
> are you sure?
> i tried this (but might have made a mistake) and the result i got was 1
> single (long) string.
> the original result, a list of strings, is much more readable.
>From the efficency guide:

When you have a deep list of depth 1 you can flatten it using append/1 
[...]

NOTE: If your deep list is a list of strings you will not get the wanted result using flatten. Remember that strings are lists. See example below:

      > lists:append([["foo"], ["bar"]]).
      ["foo","bar"]
      > lists:flatten([["foo"], ["bar"]]).
      "foobar"
    
-- 
/m.v.h Ingela

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