A graph data structure usable in @safe pure nothrow functions

[FG via Digitalmars-d]

On 2014-05-25 16:39, w0rp wrote:
> I have been wanting graph types which can be used in @safe pure nothrow functions. The big blocker on this was what associative arrays could offer.
> The current associative array implementation couldn't get me all the way there, so I wrote my own hashmap type.

get and setDefault are nice, but can be easily done as small UFCS wrappers around the "element in array" expression.
What was blocking you in the current implementation of associative arrays?
Can't it be fixed without having to come up with a custom map type?