2.3 Literals: quote and #%datum

Many forms are implicitly quoted (via #%datum) as literals. See Expansion Steps for more information.

Quoting: quote and ’ in Guide: PLT Scheme introduces quote.

(quote datum)

Produces a constant value corresponding to datum (i.e., the representation of the program fragment) without its lexical information, source location, etc. Quoted pairs, vectors, and boxes are immutable.

Examples:

> (quote x)

x

> (quote (+ 1 2))

(+ 1 2)

> (+ 1 2)

3

(#%datum . datum)

Expands to (quote datum), as long as datum is not a keyword. If datum is a keyword, a syntax error is reported.

See also Expansion Steps for information on how the expander introduces #%datum identifiers.

Examples:

> (#%datum . 10)

10

> (#%datum . x)

x

> (#%datum . #:x)

eval:7:0: #%datum: keyword used as an expression in: #:x