What is MIME type "text/x-fsharp"?

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

text/x-fsharp is a MIME type that marks files containing F# code. It tells systems and editors that the file is plain text with specialized code.
Files using this MIME type include those with extensions like FS, FSX, and FSI.

Main use: Labeling F# source code and scripts.
Development: Aids editors in applying syntax highlighting and proper formatting.
Execution: Supports running scripts and interactive coding sessions.

This MIME type ensures that tools treat the file correctly for code editing and compiling. For more details on F#, visit F# Official Site.

Associated file extensions

.fs, .fsx, .fsi

Usage Examples

HTTP Header

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


    Content-Type: text/x-fsharp

HTML

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


    <a href="file.dat" type="text/x-fsharp">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-fsharp');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.fs, .fsx, .fsi

FAQs

What is the text/x-fsharp MIME type used for?

The text/x-fsharp MIME type represents source code written in the F# programming language. It is primarily used to identify files with extensions like .fs (source), .fsx (script), and .fsi (signature) so that web servers and text editors can handle them as code rather than generic text.

How do I configure Apache to serve F# files?

To serve F# files with the correct content type in Apache, you should update your .htaccess file or main configuration. Add the line AddType text/x-fsharp .fs .fsx .fsi to ensure browsers and clients recognize the files correctly.

How do I add text/x-fsharp support to Nginx?

In Nginx, open your mime.types file (usually located in /etc/nginx/) and add the entry text/x-fsharp fs fsx fsi;. If you cannot edit the global file, you can add a types { text/x-fsharp fs fsx fsi; } block inside your specific server or location configuration.

Why does my browser download .fsx files instead of displaying them?

Browsers often default to downloading unknown file types or those served as application/octet-stream. If your server is not configured to send the text/x-fsharp header, or if the browser doesn't have a handler for F# code, it will trigger a download. You can install browser extensions to view source code inline.

What is the difference between .fs and .fsx files?

While both use text/x-fsharp, a .fs file is typically a compiled source file used in building applications. A .fsx file is an F# script designed to be run interactively or via the F# Interactive (FSI) tool without explicit compilation.

Is text/x-fsharp a standard IANA MIME type?

The prefix x- indicates that text/x-fsharp is a non-standard or private MIME type, not officially registered in the IANA main tree. However, it is the widely accepted convention for identifying F# source code across the web and in development tools.

How do I configure IIS to handle F# files?

For Microsoft IIS, you can add a MIME map in your web.config file inside the <staticContent> section. Use the element <mimeMap fileExtension=".fs" mimeType="text/x-fsharp" /> (repeating for .fsx and .fsi) to ensure the server delivers the correct content type.

General 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.