2. Lexical conventions Upper and lower case forms of a letter are never distinguished except within character and string constants. For example, `Foo' is the same identifier as `FOO', and #x1AB is the same number as #X1ab.
Supports LL64, LLP64, LP64 and ILP64 (storage-fatty)
storage-compact does not support any of above (yet)
Ordinary storage implementation can address any Scheme object scattered on whole memory space. Both storage-fatty and storage-compact have no limitation on any 32 and 64-bit data models. But it may be limited if a storage implementation is designed to do so for some specific advantages, as like GNU Emacs' 28-bit tagged pointer does.
Only supports fixnum, and its range is varied by the user-selected underlying storage implementation. The range can be known via SRFI-77 compatible (least-fixnum) and (greatest-fixnum).
Supported.
Limited to nested use due to its setjmp/longjmp implementation. If a continuation that is not an ancestor of current continuation called, all continuation objects lying between the curent and the common ancestor of the destination are invalidated. Calling an invalidated continuation object causes an error.
The hygienic macros are fully supported.
Only integer part is implemented.
All character category-sensitive procedures and predicates (such as char-upcase) work correctly only in ASCII range. i.e. Neigher Unicode processing specified in SRFI-75 nor other non-Unicode multibyte character processing are supported in such procedures/predicates.
SigScheme's case-insensitive comparison conforms to the foldcase'ed comparison described in SRFI-75 and SRFI-13, although R5RS does not specify comparison between alphabetic and non-alphabetic char.
See the description in operations.c for further details.
SigScheme does distinguish letter case in indentifiers. Although case insensitivity is required in R5RS as follows, it is hard to accept for the our application.
2. Lexical conventions Upper and lower case forms of a letter are never distinguished except within character and string constants. For example, `Foo' is the same identifier as `FOO', and #x1AB is the same number as #X1ab.
SigScheme treats string literals as constant as specified in R5RS.
sscm> (string-set! "foo" 0 #\F) Error: in string-set!: attempted to modify immutable string: "foo"
sscm> (string-set! (string-copy "foo") 0 #\F) "Foo"
SigScheme inhibits modification of constant list object by default as specified in R5RS, if the storage implementation suports it. storage-fatty supports it, but storage-compact does not due to no bit space for pair object.
The behavior can be changed by SCM_CONST_LIST_LITERAL.
4.1.2 Literal expressions `(quote <datum>)' may be abbreviated as '<datum>. The two notations are equivalent in all respects. 'a ==> a '#(a b c) ==> #(a b c) '() ==> () '(+ 1 2) ==> (+ 1 2) '(quote a) ==> (quote a) ''a ==> (quote a) As noted in section 3.4 Storage model, it is an error to alter a constant (i.e. the value of a literal expression) using a mutation procedure like `set-car!' or `string-set!'. 6.3.2 Pairs and lists procedure: set-car! pair obj Stores obj in the car field of pair. The value returned by `set-car!' is unspecified. (define (g) '(constant-list)) (set-car! (g) 3) ==> error
SigScheme inhibits modification of constant vector object by default as specified in R5RS, if the storage implementation suports it. storage-fatty supports it, but storage-compact is not yet.
The behavior can be changed by SCM_CONST_VECTOR_LITERAL.
6.3.6 Vectors procedure: vector-set! vector k obj (vector-set! '#(0 1 2) 1 "doe") ==> error ; constant vector
SigScheme allows quote-less null list by default for convenience and performance. But it can be error as specified in R5RS, when SCM_STRICT_R5RS is enabled.
sscm> (null? ()) #t
sscm> (null? ()) Error: eval: () is not a valid R5RS form. use '() instead
Sigscheme inhibits quote-less vector literal by default, as specified in R5RS.
The behavior can be changed by SCM_STRICT_VECTOR_FORM.
6.3.6 Vectors Vectors are written using the notation #(obj ...). For example, a vector of length 3 containing the number zero in element 0, the list `(2 2 2 2)' in element 1, and the string `"Anna"' in element 2 can be written as following: #(0 (2 2 2 2) "Anna") Note that this is the external representation of a vector, not an expression evaluating to a vector. Like list constants, vector constants must be quoted: '#(0 (2 2 2 2) "Anna") ==> #(0 (2 2 2 2) "Anna")
sscm> #(1 2 3) Error: eval: #() is not a valid R5RS form. use '#() instead sscm> '#(1 2 3) #(1 2 3)
(null-environment) and (scheme-report-environment) does not return correct environemnt specified in R5RS. Current implementation returns same object of (interaction-environment).
SigScheme strictly conforms to the internal definitions defined in R5RS (cited below) if SCM_STRICT_DEFINE_PLACEMENT is enabled (default). It can be disabled to get the syntax loosen, shrink the footprint and reduce runtime cost.
5.2.2 Internal definitions Definitions may occur at the beginning of a <body> (that is, the body of a lambda, let, let*, letrec, let-syntax, or letrec-syntax expression or that of a definition of an appropriate form). Such definitions are known as internal definitions as opposed to the top level definitions described above.
Superfluous or dotted arguments are strictly rejected as an error if SCM_STRICT_ARGCHECK is enabled. Otherwise ignored. Resource-sensitive apprication could disable it.
sscm> (car '(1 2) 3 4) ERROR: in (function call): superfluous argument(s): (3 4) sscm> (symbol? 'foo . #t) ERROR: in (function call): improper argument list terminator: #t sscm> (+ 3 4 . 5) ERROR: in (reduction): improper argument list terminator: 5
sscm> (car '(1 2) 3 4) 1 sscm> (symbol? 'foo . #t) #t sscm> (+ 3 4 . 5) 7
Following R5RS syntaxes and procedures are not implemented (yet).
procedure: complex? obj
procedure: real? obj
procedure: rational? obj
procedure: exact? z
procedure: inexact? z
library procedure: gcd n1 …
library procedure: lcm n1 …
procedure: numerator q
procedure: denominator q
procedure: floor x
procedure: ceiling x
procedure: truncate x
procedure: round x
library procedure: rationalize x y
procedure: exp z
procedure: log z
procedure: sin z
procedure: cos z
procedure: tan z
procedure: asin z
procedure: acos z
procedure: atan z
procedure: atan y x
procedure: sqrt z
procedure: expt z1 z2
procedure: make-rectangular x1 x2
procedure: make-polar x3 x4
procedure: real-part z
procedure: imag-part z
procedure: magnitude z
procedure: angle z
procedure: exact->inexact z
procedure: inexact->exact z
optional procedure: transcript-on filename
optional procedure: transcript-off
Although a C implementation module-srfi1.c is existing, it is still broken and should not use for production codes. To get SRFI-1 working with SigScheme, use SLIB version of the library (will made available after some preparations).
The error procedure throws a SigScheme-specific error object in cooperate with "SRFI-34 Exception Handling for Programs". Since the error objects are represented as a list, be careful on catching an exception based on its type. If you want to distinguish the error objects from ordinary lists, use SigScheme-specific %%error-object? predicate.
sscm> (guard (obj ((pair? obj) obj)) (error "reason" 1 2 3)) #<error "reason" 1 2 3>
sscm> (define err (guard (err (#t err)) (error "reason" 1 2 3))) err sscm> err #<error "reason" 1 2 3> sscm> (pair? err) #t sscm> (car err) (#<undef> . #<undef>) sscm> (%%error-object? err) #t
Only write-with-shared-structure is implemented and read-with-shared-structure is not. The optional alias write/ss described in SRFI-38 is also defined.
The shared index starts with #1 (not #0).
sscm> (define lst (list 'a 'b)) lst sscm> (set-cdr! lst lst) #1=(a . #1#) sscm> lst #1=(a . #1#)
The d part of ~w,dF directive is acceptable, but completely ignored on output format. Since SigScheme only supports integer currently, number is always formatted as integer even if the d part is specified.
(format "~3F" 3) => " 3" (format "~3,2F" 3) => "3.00"
(format "~3F" 3) => " 3" (format "~3,2F" 3) => " 3"
Only following procedures are implemented.
Bitwise Operations
procedure: logand n1 …
procedure: bitwise-and n1 …
procedure: logior n1 …
procedure: bitwise-ior n1 …
procedure: logxor n1 …
procedure: bitwise-xor n1 …
procedure: lognot n
procedure: bitwise-not n
procedure: bitwise-if mask n0 n1
procedure: bitwise-merge mask n0 n1
procedure: logtest j k
procedure: any-bits-set? j k
And the others listed below are not.
Integer Properties
procedure: logcount n
procedure: bit-count n
procedure: integer-length n
procedure: log2-binary-factors n
procedure: first-set-bit n
Bit Within Word
procedure: logbit? index n
procedure: bit-set? index n
procedure: copy-bit index from bit
Field of Bits
procedure: bit-field n start end
procedure: copy-bit-field to from start end
procedure: ash n count
procedure: arithmetic-shift n count
procedure: rotate-bit-field n count start end
procedure: reverse-bit-field n start end
Bits as Booleans
procedure: integer->list k len
procedure: integer->list k
procedure: list->integer list
procedure: booleans->integer bool1 …
quoted-symbol by vertical bar (|) is not supported yet
FIXME
#f and '()
let and let* bindings
= predicate