Source Text and Comments

A Whim source file contains UTF-8 text. The usual file suffix is .whim. ASCII spaces, tabs, line feeds, carriage returns, vertical tabs, and form feeds separate tokens but have no other meaning. The formatter uses two spaces for each level by default.

Identifiers

An identifier starts with an ASCII letter, _, or a non-ASCII UTF-8 byte. Later bytes may also be decimal digits. A backslash joins namespace segments.

$answer2 = 42;

function café(): string {
  return 'coffee';
}

assert!(café() == 'coffee');

Whim compares names by their UTF-8 bytes. It does not fold case or normalize Unicode. Two spellings that look alike may still name different symbols.

Statements and blocks

Most simple statements end with ;:

$answer = 42;
write_line!($answer);

A block uses braces and does not take a trailing semicolon:

if (true) {
  write_line!('inside the block');
}

Control-flow headers use parentheses. This applies to if, while, for, foreach, and catch.

Comments

Whim has line comments, block comments, and doc comments:

// This comment ends with the line.

/* This comment may
   span several lines. */

/** Returns the answer. */
function answer(): int {
  return 42;
}

A doc comment belongs to the declaration that follows it. # does not start a comment. The sequence #[ starts an attribute.

Shebang line

A file may start with a Unix shebang:

#!/usr/bin/env whim

The shebang must start at byte zero. Whim treats # anywhere else as an error unless it begins an attribute.

Number literals

Integers use signed 64-bit values. The source forms are:

assert!(42 == 4_2);
assert!(0xff == 255);
assert!(0b1010 == 10);
assert!(0o755 == 493);

Underscores may split digits. A decimal integer cannot start with 0 unless it is zero. Write 0o for octal.

Floats use decimal digits and may use an exponent. A decimal point may have digits on only one side:

assert!(1.5 == 15e-1);
assert!(.5 == 0.5);
assert!(5. == 5.0);
assert!(1_000.0 == 1000.0);

The runtime stores floats as IEEE 754 double-precision values.

String tokens

Strings explains single-quoted and double-quoted strings. Backticks do not quote strings.

Top-level declarations

Functions, classes, interfaces, enums, constants, aliases, and newtypes may appear only at file or namespace scope. They cannot appear inside a function or control-flow block.

File-scope statements form that file’s executable body. A loaded file may both declare symbols and run code.