Probably is a plugin for Roblox Studio that displays the probability distributions of arbitrary Lua functions.

Probably is available for installation from within Studio via the Toolbox:

1. Open the Toolbox.
2. Select the Plugins category.
3. Search for "Probably".
4. Select Probably by Anaminus.
5. Click the Install button.

It can also be installed from the website. Installing free copies of Probably should be avoided, as they will have been authored by untrusted providers. Instead, it is recommended that you compile the plugin yourself from source.

Probably adds the Probably button to the toolbar. Clicking it will toggle the Probably window.

The window has several panels:

• Top bar: Across the top. Contains various buttons.
• Graph: On the left. Displays probability distributions. Has X and Y axes.
• Editor: On the right. Contains the editable source of the distribution function.
• Options: On the lower right, below the Editor. Contains options for configuring the plugin.
• Errors: On the bottom right, below the Options. Displays errors with the source.

In the Top bar are three buttons:

• Play/Pause: Toggles sampling. While running, the distribution function is continuously called, and the results are displayed on the Graph.
• Reset: Removes all results.
• About: Displays a panel containing information about the plugin.

The Graph displays the results of sampling as a bar graph. Results are added to buckets, and the height of each bar is the size of the bucket relative to the largest bucket.

The X axis displays the minimum and maximum values that have been observed. The Y axis displays the probability of the largest bucket.

In order to display properly, the results of the sampling are discarded whenever a new minimum or maximum value is discovered. This can cause the graph to jump or jitter.

Hovering over a bar will display the probability for the bar, and the values the bar represents. A bar has several ways to display values:

• None: Displays no value, meaning that no samples in this range have been observed.
• Single (A): The bar represents the single value A. Likely to occur with integer results.
• Range (A to B): The bar represents a range of values between A and B.

The Editor displays the source of the distribution function. While running, the Graph will be updated live as the source is edited.

The source is expected to return a function. This function will be called continuously while the plugin is running. The function receives a Random value, and must return a number. Non-number types, infinities, and NaN values are discarded. The function should avoid having side-effects.

The source is executed only whenever it changes. If the source or function contains an error, then the previous function will continue to be used until there is no longer an error. Any errors will be displayed in the bottom right corner.

There are several options for configuring the plugin:

• Resolution: The number of buckets (or bars) into which results will be distributed.
• Budget: Amount of time, per frame, that should be dedicated to sampling, in microseconds.
• Updates: The number of times the graph should be updated, per second.

Probably requires no permissions to operate.

If cloning the repository, ensure that submodules are downloaded:

git clone --recurse-submodules https://github.com/Anaminus/probably

Otherwise, ensure that submodules are up to date:

git submodule update --init --recursive

This project is built with Rojo. Run the build command, outputting to your configured plugins directory:

rojo build --output $PLUGINS_PATH

The source code and assets for Probably, except for the logo, are licensed under MIT.