REPL Integration

fsharp-ts-repl.el provides integration with F# Interactive (dotnet fsi). The REPL buffer gets tree-sitter syntax highlighting for input and regex-based highlighting for output.

Setup

Enable the REPL minor mode in F# buffers:

(add-hook 'fsharp-ts-mode-hook #'fsharp-ts-repl-minor-mode)

Commands

From a source buffer with fsharp-ts-repl-minor-mode active:

Key	Command	Description
C-c C-z	fsharp-ts-repl-switch-to-repl	Start or switch to the REPL
C-c C-c	fsharp-ts-repl-send-definition	Send definition at point
C-c C-r	fsharp-ts-repl-send-region	Send region
C-c C-b	fsharp-ts-repl-send-buffer	Send entire buffer
C-c C-l	fsharp-ts-repl-load-file	Load file via #load directive
C-c C-p	fsharp-ts-repl-send-project-references	Send project references to REPL
C-c C-i	fsharp-ts-repl-interrupt	Interrupt the REPL process
C-c C-k	fsharp-ts-repl-clear-buffer	Clear the REPL buffer

Note

When fsharp-ts-repl-minor-mode is active, C-c C-c sends the definition at point to the REPL instead of running compile. Use M-x compile directly if you need compilation while the REPL minor mode is active.

Expression Terminators

F# Interactive requires ;; to terminate expressions. fsharp-ts-repl appends ;; automatically when it's missing from the code you send, so you don't need to worry about it.

Project References

C-c C-p (fsharp-ts-repl-send-project-references) resolves assembly references and source files from the nearest .fsproj and sends #r/#load directives to FSI. This makes project types available in the REPL without manual setup.

• When Eglot is connected, it uses FsAutoComplete for instant resolution
• Without Eglot, it falls back to dotnet msbuild (slower but standalone)

Use M-x fsharp-ts-repl-generate-references-file to write the directives to a buffer for inspection instead of sending them.

Input History

Input history is persisted across sessions. The history file location is controlled by fsharp-ts-repl-history-file.

Configuration

;; Customize the program (default: "dotnet")
(setq fsharp-ts-repl-program-name "dotnet")

;; Customize arguments (default: '("fsi" "--readline-"))
(setq fsharp-ts-repl-program-args '("fsi" "--readline-"))

;; Disable syntax highlighting for REPL input
(setq fsharp-ts-repl-fontify-input nil)

;; Custom history file location
(setq fsharp-ts-repl-history-file "~/.dotnet/fsi-history")