Is it so bad to write a simple helper function?
def update_if_exists(map, key, fun) do
case Map.has_key?(map, key) do
false -> map
true -> Map.update(map, key, nil, fun)
end
end
-Greg Vaughn
> On Oct 3, 2017, at 1:40 PM, Ary Borenszweig <[email protected]> wrote:
>
> I saw it, but it's different from what I want. There are two versions:
> - get_and_update(map, key, fun): fun is called with the current value under
> key in map (or nil if key is not present in map) -> I don't want that nil, it
> will break my code
> - get_and_update!(map, key, fun): raises if there's no key
>
> I want something like this:
>
> ~~~
> Map.put_lazy(map, key, fun value -> value + 1 end)
> ~~~
>
> Here, the function is only invoked if key is present in map. `get_and_update`
> would invoke that function with `nil`.
>
>
>
> On Tuesday, October 3, 2017 at 3:00:43 PM UTC-3, Tallak Tveide wrote:
> https://hexdocs.pm/elixir/Map.html#get_and_update!/3
>
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