R7RSSmallErrata
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R7RSSmall­Errata
cowan
2016-11-01 04:53:36
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Errata from the
final draft of R7RS
. This list is unofficial.
In Section 3.1 (Variables, syntactic keywords, and regions), the claim in paragraph 2 that all variable binding constructs can be explained in terms of
lambda
does not apply to top-level bindings.
Section 7.1.5 (Transformers) doesn't make it clear that a top-level
syntax-rules
pattern must be a list pattern, not a vector pattern or an identifier pattern.
In Section 6.3 (Booleans), the procedure
boolean=?
is defined to return
#t
if the arguments are all booleans and are either all
#t
or all
#f
. The words "are all booleans and" incorrectly suggest that the value is
#f
if at least one argument is not a boolean. In fact it is an error to apply
boolean=?
to non-booleans.
In Section 4.1.2 (Literal expressions), the examples
'#
and
should be
'#\a
and
#\a
respectively.
In section 7.1.1 (Lexical structure), the escape sequence
\|
is not shown as permitted in . The list in Section 6.7 shows that it is equivalent to
. Similarly, the escape sequences
\"
and
\\
should be allowed in . This makes the same escape sequences valid in both strings and symbols.
In Section 7.3 (Derived expression types), the syntax-rules definition of
case
is incorrect; the fourth syntax rule must be moved after the fifth to avoid an improper match against the fourth rule when
=>
is present. Here is the correct version:
(define-syntax case
(syntax-rules (else =>)
((case (key ...)
clauses ...)
(let ((atom-key (key ...)))
(case atom-key clauses ...)))
((case key
(else => result))
(result key))
((case key
(else result1 result2 ...))
(begin result1 result2 ...))
((case key
((atoms ...) => result))
(if (memv key '(atoms ...))
(result key)))
((case key
((atoms ...) => result)
clause clauses ...)
(if (memv key '(atoms ...))
(result key)
(case key clause clauses ...)))
((case key
((atoms ...) result1 result2 ...))
(if (memv key '(atoms ...))
(begin result1 result2 ...)))
((case key
((atoms ...) result1 result2 ...)
clause clauses ...)
(if (memv key '(atoms ...))
(begin result1 result2 ...)
(case key clause clauses ...)))))
In Section 7.1.1, the lexical rule incorrectly omits
Bibliographic reference ![13] should link to
SRFI 4
In section 4.2.2, add "interleaving evaluations with assignments" to the definition of
letrec*
. Replace the meaningless example with this:
;; Returns the arithmetic, geometric, and
;; harmonic means of a nested list of numbers
(define (means ton)
(letrec*
((mean
(lambda (f g)
(f (/ (sum g ton) n))))
(sum
(lambda (g ton)
(if (null? ton)
(+)
(if (number? ton)
(g ton)
(+ (sum g (car ton))
(sum g (cdr ton)))))))
(n (sum (lambda (x) 1) ton)))
(values (mean values values)
(mean exp log)
(mean / /))))
Note that evaluating
(means '(3 (1 4)))
returns three values: 8/3, 2.28942848510666 (approximately), and 36/19.
In section 7.1.5, add to the alternatives for the rule.
Section 1.3.4 refers to "the initial environment" containing
, which is not true for programs. It should refer instead to "an environment containing the base library".
An example in section 5.3.3 refers to
integer-sqrt
instead of
exact-integer-sqrt
In section 4.3.1, the body of a
let-syntax
expression is said to contain "one or more definitions"; it should be "zero or more definitions".
In section 6.6 for
char-upcase/downcase/foldcase
and 6.7 for
string-upcase/downcase/foldcase
the reader is referred to UAX
#29
, but it should be TR
#44
In section 7.3, the definition of
case-lambda
should use
letrec-syntax
, not
let-syntax
In section 4.3.2 (but not in 7.1.3), change to to avoid confusion.
(removed, already in R7RS-small)
In the first bullet of the "Incompatibilities with R6RS" section, for "have to be be" read "have to be".
In numeric tower bullet of the "Incompatibilities with R6RS" section, for "but the R6RS procedures
real-valued?
rational-valued?
, and
integer-valued?
were not" read "but the semantics of the R6RS procedures
real?
rational?
, and
integer?
were not adopted. (Note that the R5RS/R7RS semantics are available in R6RS using
real-valued?
rational-valued?
, and
integer-valued?
)".
From
Richard Kelsey's R5RS errata
: In the explanation of
list-ref
, for "fewer than
elements", read "
or fewer elements". Thus,
(list-ref '(x) 1)
is an error.
In Appendix B, for "All algebraic operations except
produce exact values given exact inputs" read "The algebraic operations
, and
expt
where the second argument is a non-negative integer all produce exact values given exact inputs".
In Appendix A, the
(scheme r5rs)
library should export
syntax-rules
else
...
=>
and
In the definition of
string-for-each
, for "the elements of the
lists
" read "the elements of the
strings
".
The value of the example
(real? 2.5+0.0i)
in Section 6.2.6 is shown as
#f
, as in R6RS. This contradicts the prose explanation. No resolution of the conflict has been reached as yet.
In the definition of
fold-char
, the sentence "If the argument is an uppercase letter, the result will be either a lowercase letter or the same as the argument if the lowercase letter does not exist or is not supported by the implementation" is no longer appropriate as of Unicode 8.0, when folding began to convert Cherokee lower-case letters to upper case. Replace it with "If the result of folding is not supported by the implementation, the argument is returned".