Bitten by the lambda parameter name

Maurizio Cimadamore maurizio.cimadamore at
Tue Jul 16 08:05:47 PDT 2013

On 16/07/13 16:00, Peter Levart wrote:
> Perhaps here, an overloaded Map.computeIfAbsent that takes a Supplier 
> instead of Function would be handy. Even when you need the key to 
> construct new value, it is usually ready in some effectively-final 
> variable in the scope. And when you don't need the key, a constructor 
> reference could be applied like:
> partySetMap.computeIfAbsent(kind, HashSet::new).add(...); 

I think the underlying problem to this discussion might be that there 
are places (and computeIfAbsent seems to be one of them) where the 
lambdi-fication of the library took a somewhat convoluted path, in which 
the 'same' variables needs to be supplied multiple times in order to 
keep the chain happy (which then turns out to be problematic because of 
scoping rules).

In my eyes, computeIfAbsent also looks a bit off - i.e. wouldn't it be 
useful to provide an option to fill in default values for absent keys at 
map construction rather than at call site?


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