Bitten by the lambda parameter name

Zhong Yu zhong.j.yu at
Mon Jul 15 08:59:49 PDT 2013

On Mon, Jul 15, 2013 at 10:34 AM, Maurizio Cimadamore
<maurizio.cimadamore at> wrote:
> On 15/07/13 16:32, Maurizio Cimadamore wrote:
>> On 15/07/13 16:28, Remi Forax wrote:
>>> On 07/15/2013 05:13 PM, Maurizio Cimadamore wrote:
>>>> On 15/07/13 15:52, Remi Forax wrote:
>>>>> This snippet not compile,
>>>>>     Kind kind = ...
>>>>>     partySetMap.computeIfAbsent(kind, kind -> new
>>>>> HashSet<>()).add(party);
>>>>> Each time I write more than a hundred lines of codes that use some
>>>>> lambdas,
>>>>> I fall into this trap.
>>>>> It's very annoying !
>>>>> Rémi
>>>> Annoying yes - but there is a reason for it? If we provide special
>>>> scoping for lambda parameters then we will never be able to add
>>>> control abstraction syntax in a nice way; not saying that it's
>>>> something we want - but it's good to have option open at least.
>>> It's a crystal ball argument, in the future if we do that then ...
>>> It usually doesn't work because between now and the future, the way
>>> the feature will be introduced will change.
>> Well, yes and no - I remember we discussed a lot whether a lambda
>> should look (semantically) more like a block or an inner class. We
>> decided it should look like the former. This is a consequence of that

It is also very annoying that this doesn't compile

        int x = 1;

            int x = 2;

It is too hard to give a distinct name to every variable. Remi is
right this is a big PITA.

>> decision. I think that mixing and matching semantics on a by-need
>> basis is not a good idea.
> And - one might argue the code you are trying to write is not that
> readable in the first place (adding random suffixes just to get it
> through javac is not very elegant readability-wise, but it does convery
> the concept that the two references of 'kind' which occur very close one
> to the other are indeed unrelated).

> Maurizio
>> Maurizio
>>> In this peculiar case, if we add control abstraction syntax we will
>>> use a different syntax,
>>> so it's very annoying for no reason.
>>>> Maurizio
>>> Rémi

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