Fable: An F# to JavaScript Compiler (fable.io)

It would be great to read thoughts from someone familiar enough to compare/contrast Fable with Elm.

One quibble with the mario demo. The game feel is off; in the game he falls faster than he ascends (different gUp and gDown gravity).

One feature which seems to be unique to Fable is that the repl doesn't rely on connecting to a compiler on the server. If I type some F# code, apparently it can be compiled/transpiled right in the browser!