Previous: Whitespace and comments, Up: Lexical conventions

### 2.3 Other notations

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

. + -
These are used in numbers, and may also occur anywhere in an identifier except as the first character. 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 (section see Pairs and lists), and to indicate a rest-parameter in a formal parameter list (section see Procedures). A delimited sequence of three successive periods is also an identifier.
( )
Parentheses are used for grouping and to notate lists (section see Pairs and lists).
'
The single quote character is used to indicate literal data (section see Literal expressions).
`
The backquote character is used to indicate almost-constant data (section see Quasiquotation).
, ,@
The character comma and the sequence comma at-sign are used in conjunction with backquote (section see Quasiquotation).
"
The double quote character is used to delimit strings (section see Strings).
\
Backslash is used in the syntax for character constants (section see Characters) and as an escape character within string constants (section see Strings).
[ ] { } |
Left and right square brackets and curly braces and vertical bar are reserved for possible future extensions to the language.
#
Sharp sign is used for a variety of purposes depending on the character that immediately follows it:
#t #f
These are the boolean constants (section see Booleans).
#\
This introduces a character constant (section see Characters).
#(
This introduces a vector constant (section see Vectors). Vector constants are terminated by ) .
#e #i #b #o #d #x
These are used in the notation for numbers (section see Syntax of numerical constants).