How to use the command chroma (with examples)

Chroma is a general-purpose syntax highlighter command. It is designed to automatically determine the syntax highlighting based on the file extension. In this article, we will explore different use cases of the chroma command and understand its various options.

Use case 1: Highlight source code from a file with the Python lexer and output to stdout

Code:

chroma --lexer python path/to/source_file.py

Motivation: This use case is ideal when we want to highlight the source code of a Python file in the terminal itself without saving it to a file. It is useful for quick reviews and debugging purposes.

Explanation:

• --lexer python: Specifies the lexer to use is Python.
• path/to/source_file.py: Path to the source code file to highlight.

Example Output: The command will highlight the source code in the Python lexer and display it in the terminal.

Use case 2: Highlight source code from a file with the Go lexer and output to an HTML file

Code:

chroma --lexer go --formatter html path/to/source_file.go > path/to/target_file.html

Motivation: This use case comes handy when we want to generate an HTML file with highlighted Go source code. It can be used for creating documentation or sharing code snippets with others.

Explanation:

• --lexer go: Specifies the lexer to use is Go.
• --formatter html: Specifies the formatter to use is HTML.
• path/to/source_file.go: Path to the source code file to highlight.
• > path/to/target_file.html: Redirects the output to the specified HTML file.

Example Output: The command will highlight the source code in the Go lexer and write the HTML output to the target_file.html file.

Use case 3: Highlight source code from stdin with the C++ lexer and output to an SVG file, using the Monokai style

Code:

command | chroma --lexer c++ --formatter svg --style monokai > path/to/target_file.svg

Motivation: This use case is useful when we want to highlight the source code provided through stdin (e.g., a code snippet copied from a website) and save it as an SVG file. The Monokai style is commonly used for syntax highlighting and can enhance code readability.

Explanation:

• --lexer c++: Specifies the lexer to use is C++.
• --formatter svg: Specifies the formatter to use is SVG.
• --style monokai: Specifies the style to use is Monokai.
• > path/to/target_file.svg: Redirects the output to the specified SVG file.

Example Output: The command will highlight the source code in the C++ lexer using the Monokai style and save the SVG output to the target_file.svg file.

Use case 4: List available lexers, styles, and formatters

Code:

chroma --list

Motivation: This use case is helpful when you want to explore the available lexers, styles, and formatters that can be used with the chroma command. It provides a comprehensive list for reference purposes.

Explanation:

• --list: Lists all the available lexers, styles, and formatters supported by chroma.

Example Output: The command will display a list of available lexers, styles, and formatters supported by the chroma command.

Conclusion:

The chroma command is a versatile tool for syntax highlighting. It can automatically determine the appropriate lexer based on the file extension. By using the various options provided, you can customize the output format, style, and target file. Whether it’s highlighting code for review, generating HTML documentation, or saving highlighted code as an SVG file, the chroma command provides a convenient way to enhance the legibility of source code.