YEN Language for Visual Studio Code

Full-featured language support for the YEN programming language — a statically-typed systems language combining performance with modern features like pattern matching, lambdas, and memory safety.

Features

Syntax Highlighting

Rich, semantic syntax highlighting for all YEN language constructs:

Keywords — control flow, declarations, modifiers
Strings — double/single quotes, raw strings (r"..."), triple-quoted ("""..."""), interpolation (${expr})
Numbers — decimal, float, hex (0xFF), binary (0b101), scientific (1.5e-10)
Comments — line (//, #) and block (/* ... */)
Functions — declarations, calls, lambdas (|x| x * 2)
Types — classes, structs, enums, traits, primitives
Operators — arithmetic, logical, bitwise, range (.., ..=), pipe (|>), null coalescing (??)
Pattern matching — match arms, guards (when), wildcards (_), ranges
Built-in functions — 200+ standard library functions with distinct coloring

Run YEN Programs

Execute YEN files directly from VS Code:

Action	Shortcut
Run file (output panel)	`F5`
Run file (terminal)	`Ctrl+F5` / `Cmd+F5`
Run selected text	`Shift+Enter`

Also available via:

Editor title bar play button
Right-click context menu
Command palette (Ctrl+Shift+P → "YEN:")

Error Diagnostics

Errors from the YEN interpreter are automatically parsed and displayed as inline diagnostics in the editor with red underlines and problem panel entries.

Auto-Completion

IntelliSense for:

All YEN keywords (func, match, defer, class, ...)
200+ built-in functions (str_split, math_sqrt, http_get, ...)
Type names (int, float, string, bool, ...)
Constants (math_PI, math_E, math_INF, ...)

Hover Documentation

Hover over keywords and built-in functions to see inline documentation with usage examples.

Code Snippets

50+ snippets for common patterns:

Prefix	Description
`func`	Function declaration
`class`	Class with constructor
`struct`	Struct definition
`enum`	Enum definition
`match`	Match expression
`matchg`	Match with guards
`for`	For-in loop
`forr`	For loop with range
`try`	Try-catch block
`lam`	Lambda expression
`pipe`	Pipe operator chain
`httpget`	HTTP GET request
`server`	HTTP server
`describe`	Test suite
`lcomp`	List comprehension
`mfr`	Map/filter/reduce pipeline

Type the prefix and press Tab to expand.

Additional Features

Bracket pair colorization enabled by default
Auto-closing pairs for {}, [], (), "", '', ||
Code folding for blocks, functions, classes
Status bar shows YEN indicator when editing .yen files
Indentation rules for automatic indent/outdent

Configuration

Setting	Default	Description
`yen.interpreterPath`	`"yen"`	Path to the YEN interpreter
`yen.runArgs`	`[]`	Extra arguments for the interpreter
`yen.showOutputOnRun`	`true`	Show output panel when running
`yen.clearOutputOnRun`	`true`	Clear output before each run
`yen.saveBeforeRun`	`true`	Auto-save before running

Quick Start

Install this extension
Open a .yen file
Press F5 to run

If the YEN interpreter is not in your PATH, configure it:

Open Command Palette (Ctrl+Shift+P)
Type "YEN: Set Interpreter Path"
Enter the full path to the yen executable

Example

// Hello World in YEN
func main() {
    let name = "World";
    print "Hello, ${name}!";

    let numbers = [1, 2, 3, 4, 5];
    let squares = [x ** 2 for x in numbers];
    print "Squares: ${squares}";

    match (list_length(squares)) {
        0 => print "Empty";
        1..5 => print "Small list";
        n when n >= 5 => print "Large list";
        _ => print "Unknown";
    }
}

Requirements

Visual Studio Code 1.75.0 or later
YEN interpreter installed (download)

License

MIT

YEN Language

yen-lang