Clash (Haskell) and Chisel (Scala) are vastly superior HDLs. Clash is actually a compiler plugin that compiles a large subset of Haskell to hardware, while chisel is a DSL.
Another Haskell Hardware DSL is Lava: http://ku-fpg.github.io/software/kansas-lava/ Chisel is very similar to Lava in many ways although I think Chisel has been used for larger designs.
As you can see, it's just plain old Haskell. Clash is really just a few GHC extensions and plugins. Spits out Verilog, SystemVerilog, or VHDL. You can also compile it to a regular executable, which means you don't have to use shitty HDL debugging software; you just debug the executable like normal (including error messages and stuff).
Here's a blog post for a Clash project I did, including actual hardware http://yager.io/HaSKI/HaSKI.html
And some slides from a talk I gave http://yager.io/talks/CLaSH.pdf which should give you an idea of how it works.
How much hardware experience do you have? I'm curious to know how much effort there would be in porting a Haskell library consisting of pure functions, like the Elliptic Curve Cryptography library [1]. ECC is fairly CPU intensive to verify (the best hand-written assembly implementation takes 0.5 ms per signature). This makes it a bottleneck for some operations, like verifying the Bitcoin blockchain, which contains millions of them.
I can't wait for high level libraries to start forming on top of the Clash library. The only thing left is more competition in the FPGA market, I guess, but perhaps this won't happen until non-hardware folks can actually program an FPGA?