Not saying it's the closest to what you have in mind, but you could look at the Emacs Tuareg mode for OCaml. Here is a reference card: http://www.ocamlpro.com/files/tuareg-mode.pdf
If you are a SLIME fan, you might notice that some of the key bindings to interact with the toplevel (the OCaml word for "REPL") are identical in Tuareg.
That said, although this will sound tongue-in-cheek: Having used Isabelle and Coq with their interactive editors, I find their approach better than a REPL. In these systems, you execute code directly from your source file, as opposed to (conceptually) sending snippets of code to a REPL. There is no concept of code you have written in the source (or the REPL) which is not synced up with the state of the REPL (or the source code, respectively). I wish other languages had modes like this. There seems to be one for Prolog, but I've never used it and don't know how well it works in practice: https://www.metalevel.at/ediprolog/
I've been happy with it. It's a good place to isolate your type issues and figure out how to plug things together. It helped me learn a lot about how F# does its type inference.
If you are a SLIME fan, you might notice that some of the key bindings to interact with the toplevel (the OCaml word for "REPL") are identical in Tuareg.
That said, although this will sound tongue-in-cheek: Having used Isabelle and Coq with their interactive editors, I find their approach better than a REPL. In these systems, you execute code directly from your source file, as opposed to (conceptually) sending snippets of code to a REPL. There is no concept of code you have written in the source (or the REPL) which is not synced up with the state of the REPL (or the source code, respectively). I wish other languages had modes like this. There seems to be one for Prolog, but I've never used it and don't know how well it works in practice: https://www.metalevel.at/ediprolog/