sunterlib/s48/sequences -- Finite Sequences
A sequence library in various structures dealing with
* abstract sequences defined by their behaviour
* general sequences or a union type of built-in and abstract sequences
* vectors in particular
[ for list and string libraries ,open srfi-1 resp. srfi-13 ]
The library comes in three structures:
* BEHAVED-SEQUENCES -- basic procedures for abstract sequences
* SEQUENCE-LIB -- B.S. + procedures for general sequences
* VECTOR-LIB -- procedures for vectors
The VECTOR-LIB exports some SCHEME bindings such as VECTOR-REF, but
consists mainly of generic sequence code compiled with the basic
sequence operation names bound to the corresponding vector procedures.
The library is neither complete nor tweaked. (The idea to recycle parts
of the srfi-13 code came too late.) It contains the folllowing procedures
(in the categories of srfi-13):
VECTOR-LIB SEQUENCE-LIB BEHAVED-SEQUENCES, also SL
* Predicates or so
vector? sequence? behaved-sequence?
sequence-type?
[ versions with 1 sequence and optional start & end parameters ]
vector-every sequence-every
vector-any sequence-any
[ versions with >1 sequence but no optional start & end parameters ]
vectors-every sequences-every
vectors-any sequences-any
* Constructors
make-vector make-another-sequence make-behaved-sequence/type
vector behaved-sequence/type
make-sequence-type
make-behaved-sequence-record
* List & Sequence Conversion
list->vector list->behaved-sequence/type
vector->list sequence->list
* Selection
vector-length sequence-length behaved-sequence-length
vector-ref sequence-ref behaved-sequence-ref
behaved-sequence:type
vector-copy sequence-copy
subvector subsequence
* Modification
vector-set! sequence-set! behaved-sequence-set!
sequence-fill! vector-fill! behaved-sequence-fill!
* Reverse & Append
vector-append sequence-append
* Fold, Unfold & Map
[ versions with 1 sequence and optional start & end parameters ]
vector-map sequence-map
vector-for-each sequence-for-each
vector-fold sequence-fold
vector-fold-right sequence-fold-right
[ versions with >1 sequence but no start & end parameters ]
vectors-map sequences-map
vectors-for-each sequences-for-each
vectors-fold sequences-fold
vectors-fold-right sequences-fold-right
NOTE -- Some procedures take several sequence arguments and create a
new sequence with the concrete type of the first one: SEQUENCE-APPEND
and the SEQUENCES-procedures in the Map etc. category. Problem: the
target sequence may accept only elemens of a particular type (think
of strings and characters). Solution: Provide a vector, say, as first
arg sequence:
(sequence-append "aber" '(1) '#(3 3)) breaks, but
(sequence-append '#() "aber" '(1) '#(3 3)) succeeds.
I concede, that's not totally satisfying. A shallow aftertaste of cat
pee remains in my mouth.
*
Prelude
For our purposes, (each valid state of) a sequence with length n maps a
bounded segment of integers [0:n) into a set of Scheme values, typically
Anything or Character. Any kind Se of sequences with elements in T
supports the following basic operations:
maker : make n [x] ==> s
n in [0:oo), optional x : T, s : Se
The fresh sequence s represents a sequence of length n (mapping to x)
predicate : x ==> b
x : Anything, b : Boolean
the type predicate `x in Se'
getter : ref s k ==> s[k]
s in Se, k in [0:n) with n = length s, s[k] in T
setter : set! s k x ==> unspec
s in Se, x in T, k in [0:n) with n = length s
effect: s[k] = x, s[other] as before
meter : length s ==> n
s in ST, n in [0:oo) length of sequence
This sequence facility supports the following kinds of sequences:
Vector
Behaved-Sequence := a record type (record packages data + behaviour)
Sequence := Vector | Byte-Vector | String | Proper-List | Behaved-Sequence
Behaved-Sequences carry a SEQUENCE-TYPE record that contains MAKER,
PREDICATE, etc. procedures with the properties sketched above.
They are the official backdoor where user-defined sequence types enter
the general sequence lib. There are Examples.
[ Wouldn't ABSEQUENCE have been much more beautiful than BEHAVED-SEQUENCE? ]
*
The Procedures
Optional [START END] (abbreviating [START [END]]) arguments default to 0
resp. the sequence length.
* Predicates
(vector? x) ==> b
(sequence? x) ==> b
(behaved-sequence? x) ==> b
(sequence-type? x) ==> b
Synopsis: The obvious type predicates. Note that behaved-sequences
are sequences and carry a sequence-type with them. Sequence-types
are not sequences but package the behaviour of concrete sequence types.
*
(vector-every foo? s [start end]) ==> x
(sequence-every foo? s [start end]) ==> x
Synopsis: Return the value x of (and (foo? s[start]) ... (foo? s[end-1])).
*
(vector-any foo? s [start end]) ==> x
(sequence-any foo? s [start end]) ==> x
Synopsis: Return the value x of (or (foo? s[start]) ... (foo? s[end-1])).
*
(vectors-every foo? s0 ...) ==> b
(sequences-every foo? s [start end]) ==> b
Synopsis: Return the value x of (and[0<=i<n] (foo? s0[i] ...)) with
n := min.k sequence-length sk.
*
(vectors-any foo? s0 ...) ==> b
(sequences-any foo? s [start end]) ==> b
Synopsis: Return the value x of (or[0<=i<n] (foo? s0[i] ...)) with
n := min.k sequence-length sk.
*
Constructors
(make-vector len [fill]) ==> v
(make-behaved-sequence/type st len [fill]) ==> bs
Synopsis: Make a fresh vector V (behaved-sequence BS with sequence-type
ST) of length LEN (and all elements = FILL).
*
(vector x0 ...) ==> v
(behaved-sequence/type st x0 ...) ==> bs
Synopsis: Make a fresh vector V (behaved-sequence BS with sequence-type
ST) of minimal length with the elements V[0] = X0, ... (BS[0] = X0, ...).
*
(make-sequence-type maker predicate getter setter meter) ==> st
Synopsis: Package the concrete sequence behaviour (basic procedures
described in the prelude) in the sequence-type record ST.
(make-behaved-sequence-record st data) ==> bs
Synopsis: Package the sequence-type ST and the concrete sequence DATA
in the behaved-sequence record BS.
*
List & Sequence Conversion
(list->vector xs [start end]) ==> v
(list->behaved-sequence/type st xs [start end]) ==> bs
Synopsis: Make a new vector V (behaved-sequence BS with sequence-type ST)
representing the sequence xs[start],..,xs[end-1].
*
(vector->list v [start end]) ==> xs
(sequence->list s [start end]) ==> xs
Synopsis: Return xs = (list v[start] ... v[end-1]) etc.
*
(vector-length v) ==> n
(sequence-length s) ==> n
(behaved-sequence-length bs) ==> n
Synopsis: Return length N of sequence represented by V : Vector, S :
Sequence, BS : Behaved-Sequence. You knew that, didn't you?
*
(vector-ref v k) ==> v[k]
(sequence-ref s k) ==> s[k]
(behaved-sequence-ref bs k) ==> bs[k]
*
(behaved-sequence:type bs) ==> st
Synopsis: Return sequence-type ST for concrete sequence packaged in
behaved-sequence BS.
*
(vector-copy v0 [start end]) ==> v1
(sequence-copy s0 [start end]) ==> s1
Synopsis: Copy v0[start],..,v0[end-1] into a new vector v1 of minimal
length. Resp. represent s0[start],...,s0[end-1] as a new sequence S1 of
the same type.
*
(subvector v0 start end) ==> v1
(subsequence s0 start end) ==> s1
Synopsis: Like xxx-copy with obligatory source index bounds.
*
Modification
(vector-set! v i x) ==> unspec
(sequence-set! s i x) ==> unspec
(behaved-sequence-set! bs i x) ==> unspec
Synopsis: Set v[i] := x etc.
*
(vector-fill! v x [start end]) ==> unspec
(sequence-fill! s x [start end]]) ==> unspec
(behaved-sequence-fill! bs x [start end]) ==> unspec
Synopsis: Set v[i] := x for all i in [start:end) etc.
*
Reverse & Append
(vector-append v0 ...) ==> v
(sequence-append s0 s1 ...) ==> s
Synoposis: Make a new vector V (sequence S of type(S0)) representing
you know what. See the NOTE above.
*
Fold, Unfold & Map
(vector-map f v [start end]) ==> fv
(vectors-map f v0 ...) ==> fv*
(sequence-map f s [start end]) ==> fs
(sequences-map f s0 s1 ...) ==> fs*
Synopsis: Make new vector FV (FV*, sequence FS of type(S), FS* of type(S0))
representing the sequence f(v[start]),...,f(v[end-1]), resp. the
sequence (f(v0[i],...) : 0<=i<n) with n = min.k sequence-length sk, etc.
See the NOTE above.
*
(vector-for-each proc v [start end]) ==> unspec
(vectors-for-each f v0 ...) ==> unspec
(sequence-for-each proc s [start end]) ==> unspec
(sequences-for-each proc v0 ...) ==> unspec
Synopsis: Call (proc v[i]) for all i in [start:end) in some order, resp.
call (proc v0[i] ...) for all i in [0:n) in some order with
n = min.k sequence-length vk, etc.
*
(vector-fold kons nil v [start end]) ==> w
(vectors-fold kons nil v0 ...) ==> w
(sequence-fold kons nil s0 [start end]) ==> s
(sequences-fold kons nil s0 ...) ==> s
Synopsis: Let y o x := (kons x y) resp.
y o (x0 ...) := (kons x0 ... y),
and let o be left-associative (so that we can spare us the brackets).
Compute
w = nil o v[start] o ... o v[end-1], resp.
w = nil o (v0[0] ...) o ... o (v0[n-1] ...)
with
n := min.k sequence-length vk;
etc., and see the NOTE above.
*
(vector-fold-right kons nil v [start end]) ==> w
(vectors-fold-right kons nil v0 ...) ==> w
(sequence-fold-right kons nil s0 [start end]) ==> s
(sequences-fold-right kons nil s0 ...) ==> s
Synopsis: Let x o y := (kons x y) resp.
(x0 ...) o y := (kons x0 ... y),
and let o be right-associative (so that we can spare us the brackets).
Compute
w = v[start] o ... o v[end-1] o nil, resp.
w = (v0[0] ...) o ... o (v0[n-1] ...) o nil
with
n := min.k sequence-length vk;
etc., and see the NOTE above.
*
Examples: forthcoming
*
Sela (for now).
oOo
c294d73444