On 30/04/12 07:08, Steven Blenkinsop wrote:
On Sunday, April 29, 2012, Gareth Smith wrote:
Hi,
I have written up some thoughts about a enabling a less
repetitious API for constructing hashmaps (amongst other
possibilities), here:
https://github.com/mozilla/rust/wiki/Bikeshed-impl-method-extraction
Does this make any sense?
Couldn't you just do something like:
fn hashmap <K:hash equals copy, V:copy> () -> std::map::hashmap<K, V> {
ret std::map::hashmap({|k| k.hash()}, {|k1,k2| k1.equals(k2)});
}
?
Ah, I had not considered that - and it looks to me like it should work -
but it doesn't:
hello.rs:26:31: 26:37 error: the type of this value must be known in
this context
hello.rs:26 ret std::map::hashmap({|k| k.hash()}, {|k1, k2|
k1.equals(k2)});
but this might be a type inference bug, because if it is rewritten with
type annotations then it works:
let hashfn:fn@(K)->uint = {|k| k.hash()};
let eqfn:fn@(K, K)->bool = {|a, b| a.equals(b)};
ret std::map::hashmap(hashfn, eqfn);
Considering your answer, and the other answers, I have abandoned this
bikeshed.
Gareth
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