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2.3 Other notations ¶

For a description of the notations used for numbers, see Numbers.

. + -

These are used in numbers, and can also occur anywhere in an identifier. A delimited plus or minus sign by itself is also an identifier. A delimited period (not occurring within a number or identifier) is used in the notation for pairs (see Pairs and lists), and to indicate a rest-parameter in a formal parameter list (see Procedures). Note that a sequence of two or more periods is an identifier.

( )

Parentheses are used for grouping and to notate lists (see Pairs and lists).

'

The apostrophe (single quote) character is used to indicate literal data (see Literal expressions).

`

The grave accent (backquote) character is used to indicate partly constant data (see Quasiquotation).

, ,@

The character comma and the sequence comma at-sign are used in conjunction with quasiquotation (see Quasiquotation).

"

The quotation mark character is used to delimit strings (see Strings).

\

Backslash is used in the syntax for character constants (see Characters) and as an escape character within string constants (see Strings) and identifiers (see Lexical structure).

[ ] { }

Left and right square and curly brackets (braces) are reserved for possible future extensions to the language.

#

The number sign is used for a variety of purposes depending on the character that immediately follows it:

#t #f

These are the boolean constants (see Booleans), along with the alternatives ‘#true’ ‘#false’.

#\

This introduces a character constant (see Characters).

#(

This introduces a vector constant (see Vectors). Vector constants are terminated by ‘)’.

#u8(

This introduces a bytevector constant (see Bytevectors). Bytevector constants are terminated by ‘)’.

#e #i #b #o #d #x

These are used in the notation for numbers (see Syntax of numerical constants).

#⟨n⟩= #⟨n⟩#

These are used for labeling and referencing other literal data (see Datum labels).