On Fri, 19 Jun 2009, nikhil wrote:
>
>
> Hi,
>
> Does anybody know what Symbol Literals, in Scala, are used for ?
> >From the book all I gather is that are they interned, like Java strings, and
> >the syntax is
> cheaper [ only a single quote :) ]
>
> I mean why cant we just use String literals instead ?
>
> Does it offer any advantages over strings or is it just used because its a
> short hand for strings ?
>
> Regards,
> Nikhil
>
The concept of 'Symbol Literals' is best understood from a
functional programming perspective.
In simple words it means an 'atom' or a literal used for
symbolic evaluation (usually a pattern match).
In the Scala world, 'Symbol Literal' is also known as 'Case
class' !
Here is an example that should help:
%%% code written in erlang %%%
-module(geometry).
-export([area/1]).
area({rectangle, W, H}) ->
W * H;
area({circle, R}) ->
3.14159 * R * R.
Do you notice that the area() function has 'rectangle' and
'circle' specified ?
Both 'rectangle' and 'circle' are Symbol Literals or atoms,
which serve purpose of pattern matching each of the specific
code blocks.
The same type of code in C++ can be written as:
#define RECTANGLE 1
#define CIRCLE 2
int type = some_fun();
switch(type)
{
case RECTANGLE:
....
break;
case CIRCLE:
....
break;
}
What is the purpose of RECTANGLE and CIRCLE here ? They are just
used as atoms.
Hope this helps build up the concept in a nice fashion.
Let me know.
thanks
Saifi.
