Here is a concrete proposal:

https://pharo.fogbugz.com/f/cases/19802/Make-sure-Symbol-concatenation-results-in-a-Symbol-not-a-String

This gives the following assertions:

�� �� �� �� "Concatenating 2 symbols results in abother symbol"
�� �� �� �� self assert: (#foo , #bar) == #foobar.

�� �� �� �� "Concatenating the empty symbol does not change a symbol"
�� �� �� �� self assert: (#foo, emptySymbol) == #foo.
�� �� �� �� self assert: (emptySymbol, #foo) == #foo.

�� �� �� �� "Strings and symbols can still be mixed, the receiver determines the result type"
�� �� �� �� "Symbol receiver gives symbol result"
�� �� �� �� self assert: (#foo , 'bar') == #foobar.
�� �� �� �� "String receiver gives string result"
�� �� �� �� self deny: ('foo' , #bar) == #foobar.
�� �� �� �� self assert: ('foo' , #bar) equals: #foobar.
�� �� �� �� self assert: ('foo' , #bar) equals: 'foobar'.

> On 5 Mar 2017, at 19:53, Martin McClure <martin@hand2mouse.com> wrote:
>

> On 03/05/2017 03:01 AM, Sven Van Caekenberghe wrote:
>> I also think that allowing concatenation on Symbols does not violate their immutability contract.
>>
>> As a thought experiment, what could be the problem with adding
>>
>> Symbol >> , arg
>>�� �� �� ^ (self , arg) asSymbol
>>
>> ?
>>
>
> Aside from the infinite recursion (I suspect you meant super rather than self) :-) , I wouldn't have any problem with that.
>
>>
>> (I have found the original issue raised annoying as well)
>>
>>
>>> On 5 Mar 2017, at 11:35, Peter Uhnak <i.uhnak@gmail.com>
>>>�� wrote:
>>>
>>> I don't need (or want) to mutate the receiver. Actually I thought that String is also immutable.
>>> $, could just return a new symbol instance instead. Concating symbols is quite practical for metaprogramming, as most things are named with symbols and compare by identity...
>>>
> Somewhat unfortunately, imho, Smalltalk Strings are mutable. I've not seen this feature used often, except by internal operations that could just as well be using a CharacterBuffer or whatever would replace String as the mutable thing if you made String immutable.
>
> Regards,
>
> -Martin