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Non standard read syntax

#| @dots{} |#

A multiline block comment. May be nested. Implements SRFI-30

#;EXPRESSION

Treats EXPRESSION as a comment.

#,(CONSTRUCTORNAME DATUM ...)

Allows user-defined extension of external representations. (For more information see the documentation for

SRFI-10)

#'EXPRESSION

An abbreviation for (syntax EXPRESSION).

#$EXPRESSION

An abbreviation for (location EXPRESSION).

#

SYMBOL : Syntax for keywords. Keywords are symbols that evaluate to themselves, and as such don't have to be quoted.

#<<TAG

Specifies a multiline string constant. Anything up to a line equal to TAG (or end of file) will be returned as a single string:

(define msg #<<END
"Hello, world!", she said.
END
)

is equivalent to

(define msg "\"Hello, world!\", she said.")

#<#TAG

Similar to #<<, but allows substitution of embedded Scheme expressions prefixed with # and optionally enclosed in curly brackets. Two consecutive #s are translated to a single #:

(define three 3)
(display #<#EOF
This is a simple string with an embedded `##' character
and substituted expressions: (+ three 99) ==> #(+ three 99)
(three is "#{three}")
EOF
)

prints

This is a simple string with an embedded `#' character
and substituted expressions: (+ three 99) ==> 102
(three is "3")

#> ... <#

Abbreviation for foreign-declare " ... ").

#>? ... <#

Abbreviation for (foreign-parse " ... ").

#>! ... <#

Abbreviation for (foreign-parse(declare " ... ").

#%...

Reads like a normal symbol.

#!...

Treated as a commment and ignores everything up the end of the current line. The keywords #!optional, #!rest and #!key are handled separately and returned as normal symbols. The special (self-evaluating) symbol #!eof is read as the end-of-file object. Note that if this constant appears at top-level in a loaded file, it is indistiguishable from normal end-of-file.

#cs...

Read the next expression in case-sensitive mode (regardless of the current global setting).

#ci...

Read the next expression in case-insensitive mode (regardless of the current global setting).

#+FEATURE EXPR

Equivalent to

(cond-expand (FEATURE EXPR) (else))

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