To me, this is Haskell's most appealing strength. The idea is, you can express your domain and logic in Haskell in pure functions which are highly testable, and then you can use that to generate code in any language you want. And the code you generate can have whatever zero-cost abstractions you choose to invent, all implemented in the nice, functional Haskell layer.

Haskell's strength at expressing and transforming AST's, in pure functional, understandable, testable code seems to be the key here.