I noticed that you can't put a concept in a generic.
PluggableHashAlgorithmU64 = concept x
x.open_default(self: var PluggableHashAlgorithmU64)
# if you do this:
# x.hash(self: PluggableHashAlgorithmU64; input: pointer; length:
int): uint64
# it will fail to build even though thats valid function syntax
# XXX will have to bother upstream about this goofup
x.hash(self: var PluggableHashAlgorithmU64, input: pointer, length:
int) is uint64
x.close(self: var PluggableHashAlgorithmU64)
FakeHashMap[K,V:typedesc,H:PluggableHashAlgorithmU64] = object
hash*: H
dummy_key: K
dummy_value: V
Run
In version 2.0.0 you will get an error like this:
Error: cannot instantiate FakeHashMap [type declared in
/home/icedquinn/code/science-fusedhash/fused.nim(12, 4)]
got: <typedesc[string], typedesc[int], typedesc[FakeBlake3]>
but expected: <K, V, H: PluggableHashAlgorithmU64>
Run
This is a little disappointing though I suppose not critical. Nim will
thankfully let us call whatever on `H` and try to get away with it (especially
with defensive `when compiles` to make those call hooks optional) but I thought
I'd try out concepts.
(before anyone asks, what i was trying to do is fix the icedmaps module so it
no longer relies on closures and lets you bake in the hash algorithm at compile
time)
