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Julia-repl: Run an inferior Julia REPL In A Terminal Inside Emacs

julia-repl: run an inferior Julia REPL in Emacs 

This is a minor mode for interacting with a Julia REPL running inside Emacs. The julia process is started in an ANSI terminal (term), which allows text formatting and colors, and interaction with the help system and the debugger.

It is recommended that you use this minor mode with julia-mode.


Installation and loading

Please make sure you have at least Emacs 25. The term code changed a bit since Emacs 24, and the package does not support that and earlier versions. For example, Ubuntu has had Emacs 25 since 18.04LTS.

Place this in your Emacs initialization files (eg .emacs):

(add-to-list 'load-path path-to-julia-repl)
(require 'julia-repl)
(add-hook 'julia-mode-hook 'julia-repl-mode) ;; always use minor mode

If you want to use a Julia executable other than julia in your path, see below.

If you are experiencing problems with Unicode characters in the Julia REPL, try setting the relevant coding/language environment, eg

(set-language-environment "UTF-8")


M-x julia-repl, or C-c C-z from a buffer in which the julia-repl minor mode is active starts a new inferior Julia process. The keys below can be used to interact with this process.

C-c C-aactivate if there is a Project.toml in parent directories
C-u C-c C-aactivate home project
C-c C-bsend whole buffer to REPL (using include)
C-u C-c C-bsend whole buffer to REPL (directly)
C-c C-csend region (when applicable) or line to REPL
C-c C-dinvoke @doc on symbol
C-c C-einvoke @edit on region (when applicable) or line
C-c C-llist methods of a function
C-c C-mexpand macro
C-c C-pchange directory to that of the buffer
C-c C-sprompt for buffer name suffix
C-c C-tsend whole buffer to REPL (using Revise.includet)
C-c C-vprompt for Julia executable
C-c C-zraise the REPL or create a new one (or switch back from REPL – only in vterm backend)
C-RETsend line to REPL (without bracketed paste)

All actions that send something to the REPL terminate with a newline, triggering evaluation. If you want to avoid sending a newline (eg maybe because you want to edit an expression), use prefix arguments (C-- or C-u, currently both have the same effect). This of course does not apply to C-c C-b.

All commands send code using bracketed paste. When Julia is waiting for input, control characters like ^[[200~ may show up in your buffer, this is innocuous. If you input takes a long time to evaluate, you can step through it line-by-line with C-RET.

Options for this package are exposed via the customize interface (M-x customize-group julia).

Environment variables

You can set environment variables directly from your init.el in Emacs, eg

(setenv "JULIA_NUM_THREADS" "4")

Buffer-local inferior REPL and Julia executable

The minor mode allows the user to select a particular Julia executable and optionally a different inferior buffer for each source code buffer. This allows running two versions (eg stable and master) of Julia simultaneously, and/or running multiple inferior REPLs of the same Julia version. A typical use case is trying out something quickly, without changing the state of the current process.

Julia executables

Set julia-repl-executable-records to a list of keys and executables. For example,

(setq julia-repl-executable-records
      '((default "julia")                  ; in the executable path
        (master "~/src/julia-git/julia"))) ; compiled from the repository

provides two executables. The first entry is always the default (it can have any other key).

Use C-c C-v to select one of these (julia-repl-prompt-executable). You can also set the value of julia-repl-executable-key directly to a key in the julia-repl-executable-records, eg using file variables, but make sure you select a correct value.

The name of the inferior buffer will reflect your choice: the default is *julia* (indicator omitted), while the master executable would map to *julia-master*, and so on.

Executable suffix

You can also set a suffix for the inferior buffer, if you want multiple ones in parallel. This can be a number, which will show up as <number>, or a symbol, which appears as -symbol.

It is recommended that you use C-c C-s (julia-repl-prompt-inferior-buffer-name-suffix), which prompts for a string by default. Prefix arguments modify it like this:

numerical prefixes select that integer: eg C-3 C-c C-s set the suffix to 3.

the negative prefix picks the next unused integer: eg C- C-c C-s sets the suffix to 4 if 1, 2, 3 are in use.


Switches to the julia process can be provided in the global variable julia-repl-switches, for example

(setq julia-repl-switches "-p 4")

The function julia-repl-prompt-switches will prompt for new switches, you can bind it to a key.

File local variables

If you are using the same settings for a specific file, consider using file variables. For example, if you use add-file-local-variable to create a block at the end of the Julia source file similar to

# Local Variables:
# julia-repl-executable-key: master
# julia-repl-inferior-buffer-name-suffix: tests
# julia-repl-switches: "-p 4"
# End:

then the next time you open a REPL, it will have the name *julia-master-tests*, and 4 worker processes.

Terminal backends

julia-repl can use the terminal in different ways. The default is ansi-term, which is included in Emacs, but it is recommended that you use vterm via emacs-libvterm (it is not the default since you need to install an extra package and the binary).

Some hints on interacting with term

Note some keybindings for term:

  1. C-x C-j switches to line mode, where you can kill/yank, move around the buffer, use standard Emacs keybindings,
  2. C-c C-k switches back to char mode,
  3. for scrolling, use S-<prior> and S-<next>.

See the help of term for more.

Using vterm

vterm is now the recommended backend, but for now you have to enable it explicitly because dependencies need to be available. In the long run it is hoped that it will replace ansi-term as the default backend for this package, fixing many outstanding issues.

Install emacs-libvterm and make sure you have a working installation (eg M-x vterm) should start a terminal

Evaluate (julia-repl-set-terminal-backend 'vterm) in your config file after you load julia-repl, but before you use it (and of course vterm should be loaded at some point). Switching terminal backends with already running Julia processes is not supported.

You may want to (setq vterm-kill-buffer-on-exit nil) to prevent the buffers associated with terminated Julia processes being killed automatically. This allows you to retain output and see error messages if the process does not start.

Using the @edit macro

The @edit macro can be called with C-c C-e when the julia-repl-mode minor mode is enabled. The behavior depends on the value of the JULIA_EDITOR envoronment variable in the Julia session. The command julia-repl-set-julia-editor is provided to conveniently control this from emacs.

To use "emacsclient" as a default in each Julia REPL you open in emacs, add the following code to your ~/.julia/config/startup.jl:

if haskey(ENV, "INSIDE_EMACS")
    ENV["JULIA_EDITOR"] = "emacsclient"

If you cannot edit your startup.jl, you can configure the editor in each repl after starting it with:

(add-hook 'julia-repl-hook #'julia-repl-use-emacsclient)

More colors

Julia uses more colors than the ones supported by term by default. To get the full range of colors, use eterm-256color, available from MELPA.

Note for Windows users

ansi-term is not supported on some (most?) Windows versions of Emacs. It has been confirmed to work with Emacs running in Cygwin. You can test whether your version works with M-x ansi-term; if this errors then this package will not work for you.

Cygwin may require some rewriting of paths for include to work. After loading this package, customize the rewrite rules as

(setq julia-repl-path-rewrite-rules julia-repl-cygwin-path-rewrite-rules)

as a reasonable default, or write custom rules for julia-repl-path-rewrites.


See the issues.

Comparison to ESS

A well-known alternative is ESS, which also supports Julia. ESS is however based on comint, which does not allow a fully functioning terminal and therefore does not support the Julia REPL modes (shell, Pkg, debuggers...) and features. julia-repl is instead based on term, and so gets all the features from Julia's native REPL for free.

Download Details:

Author: tpapp
Source Code: 
License: View license

#julia #repl #emacs 

Raleigh  Hayes

Raleigh Hayes


How to Manage REPL State with integration

Integrant is a powerful library that makes clojure repl driven development much easier, in this video we'll explore how to use it

#repl  #web-development #clojure 

Shad  Blanda

Shad Blanda


What is Node.js REPL and its Usage?

REPL stands for Read Eval Print Loop and it represents a computer environment like a Windows console or Unix/Linux shell where a command is entered and the system responds with an output in an interactive mode. Node.js or Node comes bundled with a REPL environment. It performs the following tasks(Reference)

What are the usages of REPL?

  • Debug
  • execute code

How can I start working with REPL?

All you need is node on your system. (Installation Guide)

Now if run node command you can get into REPL:

Image for post

#javascript #nodejs #frontend #repl

LispREPL.jl: REPL for LispSyntax.jl

LispREPL.jl: A REPL for LispSyntax.jl

This package provides REPL functionality with Lisp syntax on top of julia. This is really Michael Hatherly's contribution factored out of LispSyntax.jl.


The lisp REPL mode is entered using the ) key in a same way as other REPL modes such as help (?) and shell (;). Unlike those modes the lisp mode is "sticky". After pressing return to evaluate the current line the mode will not switch back to the julia> mode, but instead will remain in lisp mode. To return to Julia mode press backspace.


The lisp mode prompt text and color may be set via your ENV settings. For example adding the following to your .juliarc.jl:


will set the prompt for lisp mode to a red lambda.

Download Details:

Author: Swadey
Source Code: 
License: View license

#julia #repl 

Reid  Rohan

Reid Rohan


TS-node: TypeScript Execution and REPL for Node.js


TypeScript execution and REPL for node.js, with source map support. Works with typescript@>=2.7.

Experimental ESM support

Native ESM support is currently experimental. For usage, limitations, and to provide feedback, see #1007.


ts-node is a TypeScript execution engine and REPL for Node.js.

It JIT transforms TypeScript into JavaScript, enabling you to directly execute TypeScript on Node.js without precompiling. This is accomplished by hooking node's module loading APIs, enabling it to be used seamlessly alongside other Node.js tools and libraries.


  • Automatic sourcemaps in stack traces
  • Automatic tsconfig.json parsing
  • Automatic defaults to match your node version
  • Typechecking (optional)
  • REPL
  • Write standalone scripts
  • Native ESM loader
  • Use third-party transpilers
  • Use custom transformers
  • Integrate with test runners, debuggers, and CLI tools
  • Compatible with pre-compilation for production

TypeScript REPL


# Locally in your project.
npm install -D typescript
npm install -D ts-node

# Or globally with TypeScript.
npm install -g typescript
npm install -g ts-node

Tip: Installing modules locally allows you to control and share the versions through package.json. TS Node will always resolve the compiler from cwd before checking relative to its own installation.



# Execute a script as `node` + `tsc`.
ts-node script.ts

# Starts a TypeScript REPL.

# Execute code with TypeScript.
ts-node -e 'console.log("Hello, world!")'

# Execute, and print, code with TypeScript.
ts-node -p -e '"Hello, world!"'

# Pipe scripts to execute with TypeScript.
echo 'console.log("Hello, world!")' | ts-node

# Equivalent to ts-node --cwd-mode
ts-node-cwd scripts.ts

# Equivalent to ts-node --transpile-only
ts-node-transpile-only scripts.ts

TypeScript REPL


#!/usr/bin/env ts-node

console.log("Hello, world!")

Passing CLI arguments via shebang is allowed on Mac but not Linux. For example, the following will fail on Linux:

#!/usr/bin/env ts-node --transpile-only --files
// This shebang is not portable.  It only works on Mac


You can require ts-node and register the loader for future requires by using require('ts-node').register({ /* options */ }). You can also use file shortcuts - node -r ts-node/register or node -r ts-node/register/transpile-only - depending on your preferences.

Note: If you need to use advanced node.js CLI arguments (e.g. --inspect), use them with node -r ts-node/register instead of the ts-node CLI.


TS Node exports a create() function that can be used to initialize a TypeScript compiler that isn't registered to require.extensions, and it uses the same code as register.


Mocha 6

mocha --require ts-node/register --watch-extensions ts,tsx "test/**/*.{ts,tsx}" [...args]

Note: --watch-extensions is only used in --watch mode.

Mocha 7

mocha --require ts-node/register --extensions ts,tsx --watch --watch-files src 'tests/**/*.{ts,tsx}' [...args]


ts-node node_modules/tape/bin/tape [...args]


# Create a `gulpfile.ts` and run `gulp`.

Visual Studio Code

Create a new node.js configuration, add -r ts-node/register to node args and move the program to the args list (so VS Code doesn't look for outFiles).

    "type": "node",
    "request": "launch",
    "name": "Launch Program",
    "runtimeArgs": [
    "args": [

Note: If you are using the --project <tsconfig.json> command line argument as per the Configuration Options, and want to apply this same behavior when launching in VS Code, add an "env" key into the launch configuration: "env": { "TS_NODE_PROJECT": "<tsconfig.json>" }.

IntelliJ (and WebStorm)

Create a new Node.js configuration and add -r ts-node/register to "Node parameters."

Note: If you are using the --project <tsconfig.json> command line argument as per the Configuration Options, and want to apply this same behavior when launching in IntelliJ, specify under "Environment Variables": TS_NODE_PROJECT=<tsconfig.json>.

How It Works

TypeScript Node works by registering the TypeScript compiler for .ts, .tsx, .js, and .jsx extensions. .js and .jsx are only registered when allowJs is enabled. .tsx and .jsx are only registered when jsx is enabled. When node.js has an extension registered (via require.extensions), it will use the extension internally for module resolution. When an extension is unknown to node.js, it handles the file as .js (JavaScript). By default, TypeScript Node avoids compiling files in /node_modules/ for three reasons:

  1. Modules should always be published in a format node.js can consume
  2. Transpiling the entire dependency tree will make your project slower
  3. Differing behaviours between TypeScript and node.js (e.g. ES2015 modules) can result in a project that works until you decide to support a feature natively from node.js

P.S. This means if you don't register an extension, it is compiled as JavaScript. When ts-node is used with allowJs, JavaScript files are transpiled using the TypeScript compiler.

Loading tsconfig.json

Typescript Node finds and loads tsconfig.json automatically. Use --skip-project to skip loading the tsconfig.json. Use --project to explicitly specify the path to a tsconfig.json

When searching, it is resolved using the same search behavior as tsc. By default, this search is performed relative to the directory containing the entrypoint script. In --cwd-mode or if no entrypoint is specified -- for example when using the REPL -- the search is performed relative to --cwd / process.cwd(), which matches the behavior of tsc.

For example:

  • if you run ts-node ./src/app/index.ts, we will automatically use ./src/tsconfig.json.
  • if you run ts-node, we will automatically use ./tsconfig.json.

Tip: You can use ts-node together with tsconfig-paths to load modules according to the paths section in tsconfig.json.

Configuration Options

You can set options by passing them before the script path, via programmatic usage, via tsconfig.json, or via environment variables.

ts-node --compiler ntypescript --project src/tsconfig.json hello-world.ts

Note: ntypescript is an example of a TypeScript-compatible compiler.

CLI Options

ts-node supports --print (-p), --eval (-e), --require (-r) and --interactive (-i) similar to the node.js CLI options.

  • -h, --help Prints the help text
  • -v, --version Prints the version. -vv prints node and typescript compiler versions, too
  • -c, --cwd-mode Resolve config relative to the current directory instead of the directory of the entrypoint script.
  • --script-mode Resolve config relative to the directory of the entrypoint script. This is the default behavior.

CLI and Programmatic Options

The name of the environment variable and the option's default value are denoted in parentheses.

  • -T, --transpile-only Use TypeScript's faster transpileModule (TS_NODE_TRANSPILE_ONLY, default: false)
  • -H, --compiler-host Use TypeScript's compiler host API (TS_NODE_COMPILER_HOST, default: false)
  • -I, --ignore [pattern] Override the path patterns to skip compilation (TS_NODE_IGNORE, default: /node_modules/)
  • -P, --project [path] Path to TypeScript JSON project file (TS_NODE_PROJECT)
  • -C, --compiler [name] Specify a custom TypeScript compiler (TS_NODE_COMPILER, default: typescript)
  • -D, --ignore-diagnostics [code] Ignore TypeScript warnings by diagnostic code (TS_NODE_IGNORE_DIAGNOSTICS)
  • -O, --compiler-options [opts] JSON object to merge with compiler options (TS_NODE_COMPILER_OPTIONS)
  • --cwd Behave as if invoked within this working directory. (TS_NODE_CWD, default: process.cwd())
  • --files Load files, include and exclude from tsconfig.json on startup (TS_NODE_FILES, default: false)
  • --pretty Use pretty diagnostic formatter (TS_NODE_PRETTY, default: false)
  • --skip-project Skip project config resolution and loading (TS_NODE_SKIP_PROJECT, default: false)
  • --skip-ignore Skip ignore checks (TS_NODE_SKIP_IGNORE, default: false)
  • --emit Emit output files into .ts-node directory (TS_NODE_EMIT, default: false)
  • --prefer-ts-exts Re-order file extensions so that TypeScript imports are preferred (TS_NODE_PREFER_TS_EXTS, default: false)
  • --log-error Logs TypeScript errors to stderr instead of throwing exceptions (TS_NODE_LOG_ERROR, default: false)

Programmatic-only Options

  • scope Scope compiler to files within scopeDir. Files outside this directory will be ignored. (default: false)
  • scopeDir Sets directory for scope. Defaults to tsconfig rootDir, directory containing tsconfig.json, or cwd
  • projectSearchDir Search for TypeScript config file (tsconfig.json) in this or parent directories.
  • transformers _ts.CustomTransformers | ((p: _ts.Program) => _ts.CustomTransformers): An object with transformers or a factory function that accepts a program and returns a transformers object to pass to TypeScript. Factory function cannot be used with transpileOnly flag
  • readFile: Custom TypeScript-compatible file reading function
  • fileExists: Custom TypeScript-compatible file existence function

Options via tsconfig.json

Most options can be specified by a "ts-node" object in tsconfig.json using their programmatic, camelCase names. For example, to enable --transpile-only:

// tsconfig.json
  "ts-node": {
    "transpileOnly": true
  "compilerOptions": {}

Our bundled JSON schema lists all compatible options.


Any error that is not a TSError is from node.js (e.g. SyntaxError), and cannot be fixed by TypeScript or ts-node. These are runtime issues with your code.

Import Statements

There are two options when using import statements: compile them to CommonJS or use node's native ESM support.

To compile to CommonJS, you must set "module": "CommonJS" in your tsconfig.json or compiler options.

Node's native ESM support is currently experimental and so is ts-node's ESM loader hook. For usage, limitations, and to provide feedback, see #1007.

Help! My Types Are Missing!

TypeScript Node does not use files, include or exclude, by default. This is because a large majority projects do not use all of the files in a project directory (e.g. Gulpfile.ts, runtime vs tests) and parsing every file for types slows startup time. Instead, ts-node starts with the script file (e.g. ts-node index.ts) and TypeScript resolves dependencies based on imports and references.

For global definitions, you can use the typeRoots compiler option. This requires that your type definitions be structured as type packages (not loose TypeScript definition files). More details on how this works can be found in the TypeScript Handbook.

Example tsconfig.json:

  "compilerOptions": {
    "typeRoots" : ["./node_modules/@types", "./typings"]

Example project structure:

-- tsconfig.json
-- typings/
  -- <module_name>/
    -- index.d.ts

Example module declaration file:

declare module '<module_name>' {
    // module definitions go here

For module definitions, you can use paths:

  "compilerOptions": {
    "baseUrl": ".",
    "paths": {
      "custom-module-type": ["types/custom-module-type"]

An alternative approach for definitions of third-party libraries are triple-slash directives. This may be helpful if you prefer not to change your TypeScript compilerOptions or structure your custom type definitions when using typeRoots. Below is an example of the triple-slash directive as a relative path within your project:

/// <reference types="./types/untyped_js_lib" />
import UntypedJsLib from "untyped_js_lib"

Tip: If you must use files, include, or exclude, enable --files flags or set TS_NODE_FILES=true.

Watching and Restarting

TypeScript Node compiles source code via require(), watching files and code reloads are out of scope for the project. If you want to restart the ts-node process on file change, existing node.js tools such as nodemon, onchange and node-dev work.

There's also ts-node-dev, a modified version of node-dev using ts-node for compilation that will restart the process on file change.

Download Details:

Author: TypeStrong
Source Code: 
License: MIT license

#typescript #nodejs #runtime #repl