size of an IO list

Bjorn Gustavsson <>
Mon Mar 7 11:20:18 CET 2005


As usual, the hardest part is usually coming up with a good name.
After some discussion, Kenneth and I come up with the following
suggestion for TWO new BIFs.

        iolist_size(IOList)
        iolist_to_binary(IOList)

where iolist_to_binary/1 will work like this

iolist_to_binary(IOList) ->
        size(list_to_binary([IOList])).

but be much faster (and obviously not build the temporary binary).

The reason for the new iolist_to_binary/1 BIF is that is not clear
that iolist_size/1 is any way releated to list_to_binary/1.

Comments? Other name suggestions?

/Bjorn

"Joe Armstrong \(AL/EAB\)" <> writes:

>  How about a BIF to compute the size of an I/O list?
> 
>  Why?
> 
>  I have made a deep list that I want to output (guess what's it's HTML :-)
> 
>  I need to make an HTTP header element  "Content-Length: ..."
> 
>  Which is the size of the flattened deep list , but I don't want to flatten it (horrors)
>  or traverse it (in Erlang) to find the length.
> 
>  Suitable case for a BIF?
> 
>   /Joe
> 

-- 
Björn Gustavsson, Erlang/OTP, Ericsson AB



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