Language Tour

This page is for people who already program

If you have never written code before, start with Choose your path and Lesson 1 instead. This tour assumes JavaScript, C, or Python familiarity.

Echo is interpreted. You declare types on variables and parameters; the runtime checks them when values are bound. Blocks use braces. If you know JavaScript, C, or Python, the surface should look familiar — the failure rules and scope rules will not.

This page is a first-hour map for experienced programmers. For a minimal file → run walkthrough, use Quick Start. For a teaching path, use Learn Echo.

name: str = "Echo";
version: int = 1;

fn greet(user: str) {
    say("Hello, ${user}!");
}

greet(name);
say("Version:", version);

Facts that matter early

• Not compiled. Files go lexer → parser → analyzer → interpreter.
• Declarations and parameters need types. A return requires a return type annotation on the function.
• Abort is the default on failure; inquiry and *Or twins cover expected absence — see Failure model.
• Classes and interfaces ship: new { ... } fields, methods, type methods, unbound methods, optional implements. Class inheritance does not.
• Scripting helpers: HTTP (host-gated), URL / Base64, regex, UTC dates. List prelude names with elang builtins.
• Current package version: 2.2.1 (see Known Limitations for the feature timeline).
• Comments:

// single-line

/*
multi-line
*/

Common mistakes

Missing ;:

name: str = "Echo"
say(name);

Missing braces (Python-style bare body):

if true
    say("yes");

Use:

if true {
    say("yes");
}

Where to go next

• Syntax Basics
• Variables and Types
• Control Flow
• Functions
• Modules
• Known Limitations