We introduced files to our environment back in May due to it being one of the most asked for features on the site. We knew this will add a new level of complexity, but we felt that it is a very empowering feature. I will not dive into the design and planning process here, but as always we tried to keep it as simple as possible without limiting you.

Here, we will explain the differences between eval mode (single-file) and project mode (multi-file), as well as the temporary limitations to the system.

  1. Eval Mode
  2. Project Mode
  3. File Changes

Eval Mode

A fresh repl (with the exception of repls that begin with multiple files) begin in Eval Mode. In eval mode, you can evaluate code from the console (including values declared in your program).

For example, in the following repl, try running the repl, then using the console to evaluate expressions that use the defined values.

If you are using python, you can also clear the console by using our custom replit module:

import replit

Repls in eval mode, however, cannot support additional files of the same filetype (e.g. only one .py or .js file, depending on the language). If your program programmatically creates those files, your repl will be forced into project mode. You can always return to eval mode by ensuring you only have one file with the extension of your language. This means that you can have media files (like png, gif files) and still remain in eval mode.

Project Mode

In any language where we support multiple files, you can enter Project Mode by creating a file - either by clicking on the icon. Or upload one from your computer by clicking and give it the same extension as the main file. Once a file has been uploaded or added, it can be dragged into any existing folder.

In project mode, you no longer have access to globally defined variables in the console. You also cannot import replit to clear the console in python/python3. However, you do have access to multiple files and folders. The first file (typically named main) will always be the program's entry point. You can create files both manually and programmatically.

We support uploading any file type including images, video, and audio files, which will be displayed correctly in the browser. These files can also be programmatically generated.

For example, you can upload an image, alter it programmatically, and save the result to a new image. Like this (which you can try out here):

This will put you in project mode which behaves slightly differently than the normal repl. Keep in mind The first file is always the entry point (typically named main), you won't be able to evaluate code in the console (it can only be used for STDIN), and any changes your program makes to files will be updated live.

You can edit a file's name or delete it if you wish by clicking on the icon beside it. If you're renaming your file, make sure you have the right extension for it.

Two things to note about files:

  1. They can be of any type/extension and you can use them in your code however you'd like.
  2. Files will be placed in the current working directory, generally you'd access it through the relative path './filename.ext'.

Here's a few examples on files in different languages:

File Changes

While you can programmatically create files in project mode, there are a few caveats:

  • When you change a file through your program, those changes will not be reflected until the repl stops running
  • Directories/folders cannot be programmatically generated or removed
  • Files cannot be deleted programmatically (but they can be manually deleted)
  • Because of the above, renaming a file will result in duplicating the file with the new name (since the old file won't be deleted).

We aim to fix all of these behaviors in the near future. If this functionality is important to you, please let us know on our feedback board.