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Outdated CHICKEN release
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- Outdated CHICKEN release
- Non-standard read syntax
- Multiline Block Comment
- Expression Comment
- External Representation
- Syntax Expression
- Location Expression
- Keyword
- Multiline String Constant
- Multiline String Constant with Embedded Expressions
- Foreign Declare
- Sharp Prefixed Symbol
- Bang
- Case Sensitive Expression
- Case Insensitive Expression
- Conditional Expansion
Non-standard read syntax
Multiline Block Comment
#| ... |#
A multiline block comment. May be nested. Implements SRFI-30
Expression Comment
#;EXPRESSION
Treats EXPRESSION as a comment. That is, the comment runs through the whole S-expression, regardless of newlines, which saves you from having to comment out every line, or add a newline in the middle of your parens to make the commenting of the last line work, or other things like that.
External Representation
#,(CONSTRUCTORNAME DATUM ...)
Allows user-defined extension of external representations. (For more information see the documentation for SRFI-10)
Syntax Expression
#'EXPRESSION
An abbreviation for (syntax EXPRESSION).
Location Expression
#$EXPRESSION
An abbreviation for (location EXPRESSION).
Keyword
#:SYMBOL
Syntax for keywords. Keywords are symbols that evaluate to themselves, and as such don't have to be quoted.
Multiline String Constant
#<<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.")
Multiline String Constant with Embedded Expressions
#<#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")
Foreign Declare
#> ... <#
Abbreviation for foreign-declare " ... ").
Sharp Prefixed Symbol
#%...
Reads like a normal symbol.
Bang
#!...
Interpretation depends on the directly following characters. Only the following are recognized. Any other case results in a read error.
Line Comment
- If followed by whitespace or a slash, then everything up the end of the current line is ignored
Eof Object
- If followed by the character sequence eof, then the (self-evaluating) end-of-file object is returned
DSSSL Formal Parameter List Annotation
- If followed by any of the character sequences optional, rest or key, then a symbol with the same name (and prefixed with #!) is returned
Read Mark Invocation
- If a read mark with the same name as the token is registered, then its procedure is called and the result of the read-mark procedure will be returned
Case Sensitive Expression
#cs...
Read the next expression in case-sensitive mode (regardless of the current global setting).
Case Insensitive Expression
#ci...
Read the next expression in case-insensitive mode (regardless of the current global setting).
Conditional Expansion
#+FEATURE EXPR
Equivalent to
(cond-expand (FEATURE EXPR) (else))
Previous: Extensions to the standard