Strings and Interpolation

Learning Echo from scratch?

Start with Lesson 7 — Strings. This page is the full string surface (format, escapes, …).

Quotes, escapes, ${...} interpolation, and format (positional + named).

name: str = "Echo";
message: str = "Hello, ${name}!";
formatted: str = "Score: {}".format(42);
named: str = "Score: {score}".format({ score: 42 });

name: str = "Echo";
count: int = 5;
ok: bool = true;
missing: dynamic = null;

say("Name: ${name}");
say("Count: ${count}");
say("OK: ${ok}");
say("Missing: ${missing}");
say("Hello, {}!".format(name));
say("Hello, {who}!".format({ who: name }));

Name: Echo
Count: 5
OK: true
Missing: null
Hello, Echo!
Hello, Echo!

Notes

Quotes

Both styles work:

a: str = "Echo";
b: str = 'Echo';

Triple quotes may span lines and still interpolate:

block: str = """
hello ${name}
""";

Escapes

Supported escapes:

\\
\"
\'
\n
\t
\r

Interpolation

Interpolation uses Echo-style output rules, so booleans print as true and false, and null prints as null.

format(...)

Supported placeholders:

{}
{0}
{1}
{name}
{{
}}

Named placeholders take values from a trailing hash:

say("Hello, {name}!".format({ name: "Echo" }));
say("{0} scored {points}".format("Ada", { points: 42 }));

Common Mistakes

Missing closing brace in interpolation

say("Hello ${name");

Expecting advanced formatting like width or precision

This is not supported.

Assuming single quotes are raw strings

Echo still processes escapes and interpolation tokenization.

Named placeholder without a trailing hash

say("{name}".format("Echo"));  // error — pass { name: "Echo" }

Current Limitation

• format() has no width / precision / alignment specs.
• No raw string syntax.
• Invalid characters inside ${...} may fail later than expected.

See Also

• Variables and Types
• Built-in Methods
• Known Limitations