What is MIME type "text/x-common-lisp"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

text/x-common-lisp is a MIME type for files written in the Lisp family. It tells systems these plain text files use Lisp syntax.

This type uses the non‐standard x- prefix. It is common in environments that work with Common Lisp and its variants. Tools like text editors, integrated development environments, and compilers use it to apply the correct syntax coloring and formatting automatically.

Syntax Highlighting: Editors recognize Lisp structures and keywords.
Tool Integration: Compilers and linters process Lisp code accurately.
File Association: Operating systems link these files to specialized editing tools.

Files declared as text/x-common-lisp are usually Lisp source or related scripts. They include files for Common Lisp (for example, CL, LISP, LSP), Emacs Lisp (EL, EMACS), and other dialects.

Some files may also include related template or configuration formats—like those used by KiCad layouts (KICAD_PCB, KICAD_MOD, KICAD_WKS)—or even files with S-expression syntax from other domains (WAT, WAST).

This MIME type streamlines development workflows by ensuring the appropriate handling of Lisp code across various tools and platforms.

For additional insight, consider checking out resources from the Common Lisp community or the GNU Emacs project.

Associated file extensions

.srt, .md, .asd, .l, .el, .jl, .ny, .cl, .lsp, .emacs, .lisp, .wat, .nl, .kicad_pcb, .emacs.desktop, .kicad_mod, .kicad_wks, .lfe, .nlogo, .podsl, .sexp, .wast

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: text/x-common-lisp

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="text/x-common-lisp">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');
    
    http.createServer((req, res) => {
      res.setHeader('Content-Type', 'text/x-common-lisp');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.srt, .md, .asd, .l, .el, .jl, .ny, .cl, .lsp, .emacs, .lisp, .wat, .nl, .kicad_pcb, .emacs.desktop, .kicad_mod, .kicad_wks, .lfe, .nlogo, .podsl, .sexp, .wast

FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.