[[tags: egg]]

[[toc:]]

== SRFI-160: Homogeneous numeric vector libraries

=== Abstract

This SRFI describes a set of operations on
[[https://srfi.schemers.org/srfi-4/srfi-4.html|SRFI 4]] homogeneous vector
types (plus a few additional types) that are closely analogous to the vector
operations library, [[https://srfi.schemers.org/srfi-133/srfi-133.html|SRFI
133]]. An external representation is specified which may be supported by the
read and write procedures and by the program parser so that programs can
contain references to literal homogeneous vectors.

For more information see: [[https://srfi.schemers.org/srfi-160/|SRFI-160:
Homogeneous numeric vector libraries]]

=== Rationale

Like lists, Scheme vectors are a heterogeneous datatype which impose no
restriction on the type of the elements. This generality is not needed for
applications where all the elements are of the same type. The use of Scheme
vectors is not ideal for such applications because, in the absence of a
compiler with a fancy static analysis, the representation will typically use
some form of boxing of the elements which means low space efficiency and slower
access to the elements. Moreover, homogeneous vectors are convenient for
interfacing with low-level libraries (e.g. binary block I/O) and to interface
with foreign languages which support homogeneous vectors. Finally, the use of
homogeneous vectors allows certain errors to be caught earlier.

This SRFI specifies a set of homogeneous vector datatypes which cover the most
practical cases, that is where the type of the elements is numeric (exact
integer or inexact real or complex) and the precision and representation is
efficiently implemented on the hardware of most current computer architectures
(8, 16, 32 and 64 bit integers, either signed or unsigned, and 32 and 64 bit
floating point numbers).

This SRFI extends SRFI 4 by providing the additional {{c64vector}} and
{{c128vector}} types, and by providing analogues for almost all of the
heterogeneous vector procedures of SRFI 133. There are some additional
procedures, most of which are closely analogous to the string procedures of
[[https://srfi.schemers.org/srfi-152/srfi-152.html|SRFI 152]].

Note that there are no conversions between homogeneous vectors and strings in
this SRFI. In addition, there is no support for u1vectors (bitvectors)
provided, not because they are not useful, but because they are different
enough in both specification and implementation to be put into a future SRFI of
their own.

=== Specification

There are eight datatypes of exact integer homogeneous vectors (which will be
called integer vectors):

* s8vector: signed exact integer in the range -2^7 to 2^7-1
* u8vector: unsigned exact integer in the range 0 to 2^8-1
* s16vector: signed exact integer in the range -2^15 to 2^15-1
* u16vector: unsigned exact integer in the range 0 to 2^16-1
* s32vector: signed exact integer in the range -2^31 to 2^31-1
* u32vector: unsigned exact integer in the range 0 to 2^32-1
* s64vector: signed exact integer in the range -2^63 to 2^63-1
* u64vector: unsigned exact integer in the range 0 to 2^64-1

All are part of SRFI 4.

There are two datatypes of inexact real homogeneous vectors (which will be
called ''float vectors''):

* f32vector: inexact real, typically 32 bits
* f64vector: inexact real, typically 64 bits

These are also part of SRFI 4.

{{f64vectors}} must preserve at least as much precision and range as
{{f32vectors}}. (See the implementation section for details.)

And there are two datatypes of inexact complex homogeneous vectors (which will
be called complex vectors):

<type>c64vector</type>

inexact complex, typically 64 bits

<type>c128vector</type>

inexact complex, typically 128 bits

These are not part of SRFI 4.

{{c128vectors}} must preserve at least as much precision and range as
{{c64vectors}}. (See the implementation section for details.)

Each element of a homogeneous vector must be valid. That is, for an integer
vector, it must be an exact integer within the inclusive range specified above;
for a float vector, it must be an inexact real number; and for a complex
vector, it must be an inexact complex number. It is an error to try to use a
constructor or mutator to set an element to an invalid value.

=== Additions to the specification

The CHICKEN implementation adds a couple of features to the SRFI specification.
It prints {{c64vector}} and {{c128vector}} as {{#!c64(...)}} and
{{#!c128(...)}}, respectively, with the appropriate sharp-read-syntax
{{'#!c64(...)}} and {{'#!c128(...)}}.

It also exports the following two procedures for access to the underlying
srfi-4 vectors that make up the body of complex vectors:

<procedure>(c128vector-body c128vec)</procedure>

Returns the {{f64vector}} body of {{c128vec}}.

<procedure>(c64vector-body c64vec)</procedure>

Returns the {{f32vector}} body of {{c64vec}}.

=== Notation

So as not to multiply the number of procedures described in this SRFI beyond
necessity, a special notational convention is used. The description of the
procedure make-@vector is really shorthand for the descriptions of the twelve
procedures {{make-s8vector}}, {{make-u8vector}}, ... {{make-c128vector}}, all
of which are exactly the same except that they construct different homogeneous
vector types. Furthermore, except as otherwise noted, the semantics of each
procedure are those of the corresponding SRFI 133 procedure, except that it is
an error to attempt to insert an invalid value into a homogeneous vector.
Consequently, only a brief description of each procedure is given, and SRFI 133
(or in some cases SRFI 152) should be consulted for the details. It is worth
mentioning, however, that all the procedures that return one or more vectors
(homogeneous or heterogeneous) invariably return newly allocated vectors
specifically.

In the section containing specifications of procedures, the following notation
is used to specify parameters and return values:

; {{vec}} : Must be a heterogeneous vector, i.e. it must satisfy the predicate vector?.

; {{@vec}}, {{@to}}, {{@from}} : Must be a homogeneous vector, i.e. it must satisfy the predicate {{@vector?}}. In {{@vector-copy!}} and {{reverse-@vector-copy!}}, {{@to}} is the destination and {{@from}} is the source.

; {{i}}, {{j}}, {{start}}, {{at}} : Must be an exact-nonnegative-integer less than the length of the {{@vector}}. In {{@vector-copy!}} and {{reverse-@vector-copy!}}, at refers to the destination and {{start}} to the source.

; {{end}} : Must be an exact-nonnegative-integer not less than {{start}} and not greater than the length of the vector. This indicates the index directly before which traversal will stop -- processing will occur until the index of the vector is one less than {{end}}. It is the open right side of a range.

; {{f}} : Must be a procedure taking one or more arguments, which returns (except as noted otherwise) exactly one value.

; {{pred}} : Must be a procedure taking one or more arguments that returns one value, which is treated as a boolean.

; {{=}} :  Must be an equivalence procedure.

; {{obj}}, {{seed}}, {{knil}} : A scheme object.

; {{fill}}, {{value}} : Any number that is valid with respect to the {{@vec}}.

; {{[something]}} : An optional argument; it needn't necessarily be applied. Something needn't necessarily be one thing; for example, this usage of it is perfectly valid: {{[start [end]]}} and is indeed used quite often.

; {{something ...}} : Zero or more somethings are allowed to be arguments.

; {{something[1] something[2] ...}} : At least one something must be arguments.

=== Packaging

For each {{@vector}} type, there is a corresponding library named (srfi 160 @),
and if an implementation provides a given type, it must provide that library as
well. In addition, the library (srfi 160 base) provides a few basic procedures
for all {{@vector}} types. If a particular type is not provided by an
implementation, then it is an error to call the corresponding procedures in
this library. Note that there is no library named (srfi 160).

=== Procedures

The procedures shared with SRFI 4 are marked with {{SRFI 4}}. The procedures
with the same semantics as SRFI 133 are marked with {{SRFI 133}}. The
procedures analogous to SRFI 152 string procedures are marked with {{SRFI 152}}.

==== Constructors

<procedure>(make-@vector size [fill]) -> @vector</procedure>

Returns a {{@vector}} whose length is size. If fill is provided, all the
elements of the {{@vector}} are initialized to it.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#constructors|SRFI 4]]

<procedure>(@vector value ...) -> @vector</procedure>

Returns a {{@vector}} initialized with values.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#constructors|SRFI 4]]

<procedure>(@vector-unfold f length seed) -> @vector</procedure>

Creates a vector whose length is length and iterates across each index {{k}}
between 0 and {{length - 1}}, applying {{f}} at each iteration to the current
index and current state, in that order, to receive two values: the element to
put in the kth slot of the new vector and a new state for the next iteration.
On the first call to {{f}}, the state's value is seed.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

<procedure>(@vector-unfold-right f length seed) -> @vector</procedure>

The same as @vector-unfold, but initializes the {{@vector}} from right to left.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

<procedure>(@vector-copy @vec [start [end]]) -> @vector</procedure>

Makes a copy of the portion of {{@vec}} from {{start}} to {{end}} and returns
it.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

<procedure>(@vector-reverse-copy @vec [start [end]]) -> @vector</procedure>

The same as {{@vector-copy}}, but in reverse order.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

<procedure>(@vector-append @vec ...) -> @vector</procedure>

Returns a {{@vector}} containing all the elements of the {{@vecs}} in order.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

<procedure>(@vector-concatenate list-of-@vectors) -> @vector</procedure>

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

The same as {{@vector-append}}, but takes a list of {{@vectors}} rather than
multiple arguments.

<procedure>(@vector-append-subvectors [@vec start end] ...) -> @vector</procedure>

Concatenates the result of applying {{@vector-copy}} to each triplet of
{{@vec}}, {{start}}, {{end}} arguments, but may be implemented more
efficiently.

[[https://wiki.call-cc.org/eggref/5/srfi-133#constructors|SRFI 133]]

==== Predicates

<procedure>(@? obj) -> boolean</procedure>

Returns {{#t}} if obj is a valid element of an {{@vector}}, and {{#f}}
otherwise.

<procedure>(@vector? obj) -> boolean</procedure>

Returns {{#t}} if obj is a {{@vector}}, and {{#f}} otherwise.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#predicates|SRFI 4]]

<procedure>(@vector-empty? @vec) -> boolean</procedure>

Returns {{#t}} if {{@vec}} has a length of zero, and {{#f}} otherwise.

[[https://wiki.call-cc.org/eggref/5/srfi-133#predicates|SRFI 133]]

<procedure>(@vector= @vec ...) -> boolean</procedure>

Compares the {{@vecs}} for elementwise equality, using = to do the comparisons.
Returns {{#f}} unless all {{@vectors}} are the same length.

[[https://wiki.call-cc.org/eggref/5/srfi-133#predicates|SRFI 133]]

==== Selectors

<procedure>(@vector-ref @vec i) -> value</procedure>

Returns the ith element of {{@vec}}.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#getters|SRFI 4]]

<procedure>(@vector-length @vec) -> exact-nonnegative-integer</procedure>

Returns the length of {{@vec}}

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#length|SRFI 4]]

==== Iteration

<procedure>(@vector-take @vec n) -> @vector</procedure>

Returns a {{@vector}} containing the first {{n}} elements of {{@vec}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#selection|SRFI 152]]

<procedure>(@vector-take-right @vec n) -> @vector</procedure>

Returns a {{@vector}} containing the last {{n}} elements of {{@vec}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#selection|SRFI 152]]

<procedure>(@vector-drop @vec n) -> @vector</procedure>

Returns a {{@vector}} containing all except the first {{n}} elements of
{{@vec}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#selection|SRFI 152]]

<procedure>(@vector-drop-right @vec n) -> @vector</procedure>

Returns a {{@vector}} containing all except the last {{n}} elements of
{{@vec}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#selection|SRFI 152]]

<procedure>(@vector-segment @vec n) -> list</procedure>

Returns a list of {{@vectors}}, each of which contains n consecutive elements
of {{@vec}}. The last {{@vector}} may be shorter than {{n}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#replication-and-splitting|SRFI 152]]

<procedure>(@vector-fold kons knil @vec @vec2 ...) -> object</procedure>

When one {{@vector}} argument {{@vec}} is given, folds {{kons}} over the
elements of {{@vec}} in increasing order using {{knil}} as the initial value.
The {{kons}} procedure is called with the state first and the element second,
as in SRFIs 43 and 133 (heterogeneous vectors). This is the opposite order to
that used in SRFI 1 (lists) and the various string SRFIs.

When multiple {{@vector}} arguments are given, {{kons}} is called with the
current state value and each value from all the vectors; {{@vector-fold}} scans
elements from left to right. If the lengths of vectors differ, only the portion
of each vector up to the length of the shortest vector is scanned.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-fold-right kons knil @vec @vec2 ...) -> object</procedure>

When one {{@vector}} argument {{@vec}} is given, folds {{kons}} over the
elements of {{@vec}} in decreasing order using {{knil}} as the initial value.
The {{kons}} procedure is called with the state first and the element second,
as in SRFIs 43 and 133 (heterogeneous vectors). This is the opposite order to
that used in SRFI 1 (lists) and the various string SRFIs.

When multiple {{@vector}} arguments are given, {{kons}} is called with the
current state value and each value from all the vectors; {{@vector-fold-right}}
scans elements from right to left. If the lengths of vectors differ, only the
portion of each vector up to the length of the shortest vector is scanned.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-map f @vec @vec2 ...) -> @vector</procedure>

Iterate over the elements of {{@vec}} and apply {{f}} to each, returning a
{{@vector}} of the results.

If more than one vector is passed, {{f}} gets one element from each vector as
arguments. If the lengths of the vectors differ, iteration stops at the end of
the shortest vector.

If {{@vector-map}} returns more than once (i.e. because of a continuation
captured by {{f}}), the values returned or stored by earlier returns may be
mutated.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-map! f @vec @vec2 ...) -> unspecified</procedure>

Iterate over the elements of {{@vec}} and apply {{f}} to each, returning an
undefined value with the results placed back in {{@vec}}.

If more than one vector is passed, {{f}} gets one element from each vector as
arguments. If the lengths of the vectors differ, iteration stops at the end of
the shortest vector. Only {{@vec}} is modified even when multiple vectors are
passed.

If {{@vector-map!}} returns more than once (i.e. because of a continuation
captured by {{f}}), the values returned or stored by earlier returns may be
mutated.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-for-each f @vec @vec2 ...) -> unspecified</procedure>

Iterate over the elements of {{@vec}} and apply {{f}} to each, returning an
undefined value with no change to the passed {{@vec}}s.

If more than one vector is passed, {{f}} gets one element from each vector as
arguments. If the lengths of the vectors differ, iteration stops at the end of
the shortest vector.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-count pred? @vec @vec2 ...) -> exact-nonnegative-integer</procedure>

Call {{pred?}} on each element of {{@vec}} and return the number of calls that
return true.

When multiple vectors are given, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are given for each iteration, which stops at the end of the shortest vector.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

<procedure>(@vector-cumulate f knil @vec) -> @vector</procedure>

Like {{@vector-fold}}, but returns an {{@vector}} of partial results rather
than just the final result.

[[https://wiki.call-cc.org/eggref/5/srfi-133#iteration|SRFI 133]]

==== Searching

<procedure>(@vector-take-while pred? @vec) -> @vector</procedure>

Return the shortest prefix of {{@vec}} all of whose elements satisfy
{{pred?}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#searching|SRFI 152]]

<procedure>(@vector-take-while-right pred? @vec) -> @vector</procedure>

Return the shortest suffix of {{@vec}} all of whose elements satisfy
{{pred?}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#searching|SRFI 152]]

<procedure>(@vector-drop-while pred? @vec) -> @vector</procedure>

Drops the longest initial prefix of {{@vec}} such that all its elements
satisfy pred.

[[https://wiki.call-cc.org/eggref/5/srfi-152#searching|SRFI 152]]

<procedure>(@vector-drop-while-right pred? @vec) -> @vector</procedure>

Drops the longest initial suffix of {{@vec}} such that all its elements
satisfy pred.

[[https://wiki.call-cc.org/eggref/5/srfi-152#searching|SRFI 152]]

<procedure>(@vector-index pred? @vec @vec2 ...) -> (or exact-nonnegative-integer #f)</procedure>

Return the index of the first element of {{@vec}} that satisfies {{pred?}}.

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are passed for each iteration. If the lengths of vectors differ, iteration
stops at the end of the shortest one.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-index-right pred? @vec @vec2 ...) -> (or exact-nonnegative-integer #f) </procedure>

Return the index of the last element of {{@vec}} that satisfies {{pred?}}.

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are passed for each iteration. Lengths of vectors must be the same.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-skip pred? @vec @vec2 ...) -> (or exact-nonnegative-integer #f)</procedure>

Returns the index of the first element of {{@vec}} that does not satisfy
{{pred?}}.

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are passed for each iteration. If the lengths of vectors differ, iteration
stops at the end of the shortest one.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-skip-right pred? @vec @vec2 ...) -> (or exact-nonnegative-integer #f)</procedure>

Returns the index of the last element of {{@vec}} that does not satisfy
{{pred?}}.

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are passed for each iteration. Lengths of vectors must be the same.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-any pred? @vec @vec2 ...) -> (or value boolean)</procedure>

Returns first non-false result of applying {{pred?}} on a element from the
{{@vec}}, or {{#f}} if there is no such element. If {{@vec}} is empty, returns
#t

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
are passed for each iteration. If the lengths of vectors differ, it stops at
the end of the shortest one.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-every pred? @vec @vec2 ...) -> (or value boolean)</procedure>

If all elements from {{@vec}} satisfy {{pred?}}, return the last result of
{{pred?}}. If not all do, return {{#f}}. If {{@vec}} is empty, return #t

When multiple vectors are passed, {{pred?}} must take the same number of
arguments as the number of vectors, and corresponding elements from each vector
is passed for each iteration. If the lengths of vectors differ, it stops at the
end of the shortest one.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-partition pred? @vec) -> @vector integer</procedure>

Returns an {{@vector}} of the same type as {{@vec}}, but with all elements
satisfying {{pred?}} in the leftmost part of the vector and the other elements
in the remaining part. The order of elements is otherwise preserved. Returns
two values, the new {{@vector}} and the number of elements satisfying
{{pred?}}.

[[https://wiki.call-cc.org/eggref/5/srfi-133#searching|SRFI 133]]

<procedure>(@vector-filter pred? @vec) -> @vector</procedure>

Return an {{@vector}} containing the elements of {{@vec}} that satisfy
{{pred?}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#fold-and-map-and-friends|SRFI 152]]

<procedure>(@vector-remove pred? @vec) -> @vector</procedure>

Return an {{@vector}} containing the elements of {{@vec}} that do not satisfy
{{pred?}}.

[[https://wiki.call-cc.org/eggref/5/srfi-152#fold-and-map-and-friends|SRFI 152]]


==== Mutators

<procedure>(@vector-set! @vec i value) -> unspecified</procedure>

Sets the ith element of {{@vec}} to value.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#setters|SRFI 4]]

<procedure>(@vector-swap! @vec i j) -> unspecified</procedure>

Interchanges the ith and jth elements of {{@vec}}.

<procedure>(@vector-fill! @vec fill [start [end]]) -> unspecified</procedure>

Fills the portion of {{@vec}} from {{start}} to {{end}} with the value fill.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

<procedure>(@vector-reverse! @vec [start [end]]) -> unspecified</procedure>

Reverses the portion of {{@vec}} from {{start}} to {{end}}.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

<procedure>(@vector-copy! @to at @from [start [end]]) -> unspecified</procedure>

Copies the portion of {{@from}} from {{start}} to {{end}} onto {{@to}},
starting at index at.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

<procedure>(@vector-reverse-copy! @to at @from [start [end]]) -> unspecified</procedure>

The same as {{@vector-copy!}}, but copies in reverse.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

<procedure>(@vector-unfold! f @vec start end seed) -> @vector</procedure>

Like vector-unfold, but the elements are copied into the vector {{@vec}}
starting at element {{start}} rather than into a newly allocated vector.
Terminates when {{end}} - {{start}} elements have been generated.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

<procedure>(@vector-unfold-right! f @vec start end seed) -> @vector</procedure>

The same as {{@vector-unfold!}}, but initializes the {{@vector}} from right to
left.

[[https://wiki.call-cc.org/eggref/5/srfi-133#mutators|SRFI 133]]

==== Conversion

<procedure>(@vector->list @vec [start [end]]) -> proper-list</procedure>

Returns a list, with the same elements as the argument.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#conversions|SRFI 4]]

<procedure>(reverse-@vector->list @vec [start [end]]) -> proper-list</procedure>

Returns a list, with the same elements as the argument in reverse order.

[[https://wiki.call-cc.org/eggref/5/srfi-133#conversion|SRFI 133]]

<procedure>(list->@vector proper-list) -> @vector</procedure>

Returns an {{@vector}} with the same elements as the argument.

[[https://wiki.call-cc.org/man/5/Module%20srfi-4#conversions|SRFI 4]]

<procedure>(reverse-list->@vector proper-list) -> @vector</procedure>

Returns an {{@vector}} with the same elements as the argument in reverse order.

[[https://wiki.call-cc.org/eggref/5/srfi-133#conversion|SRFI 133]]

<procedure>(@vector->vector @vec [start [end]]) -> vector</procedure>

Returns a heterogeneous vector with the same elements as the argument.

<procedure>(vector->@vector vec [start [end]]) -> @vector</procedure>

Returns an {{@vector}} with the same elements as the argument.

==== Generators

<procedure>(make-@vector-generator @vector)</procedure>

Returns a [[https://srfi.schemers.org/srfi-121/srfi-121.html|SRFI 121]]
generator that generates all the values of {{@vector}} in order. Note that the
generator is finite.

==== Comparators

<constant>@vector-comparator</constant>

Variable containing a [[https://srfi.schemers.org/srfi-128/srfi-128.html|SRFI
128]] comparator whose components provide ordering and hashing of {{@vectors}}.

==== Output

<procedure>(write-@vector @vec [ port ] ) -> unspecified</procedure>

Prints to port (the current output port by default) a representation of
{{@vec}} in the lexical syntax explained below.

=== The SRFI 160 base library

The library (srfi 160 base) is in the repository of this SRFI. It supports the
eight procedures of SRFI 4, namely make-@vector, {{@vector}}, {{@vector?}},
{{@vector-length}}, {{@vector-ref}}, {{@vector-set!}}, {{@vector->list}}, and
{{list->@vector}}, not only for the ten homogeneous vector types supported by
SRFI 4, but also for the two homogeneous vector types beyond the scope of SRFI
4, namely {{c64vectors}} and {{c128vectors}}. In addition, the {{@?}}
procedure, which is not in SRFI 4, is available for all types.

=== Acknowledgements

Thanks to all participants in the SRFI 160 mailing list over the unconscionably
long time it took me to get this proposal to finalization. Special thanks to
Shiro Kawai for bringing up many issues and contributing the code that extended
many procedures from one {{@vector}} to many.

=== Authors

* John Cowan (based on SRFI 4 by Marc Feeley)
* Shiro Kawai (contributed a major patch).
* Ported to Chicken Scheme 5 by Sergey Goldgaber

=== Maintainer

[[https://wiki.call-cc.org/users/diego-mundo|Diego A. Mundo]]

=== Repository

[[https://code.dieggsy.com/srfi-160/]]

=== Copyright

 Copyright © John Cowan 2018.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
 to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice (including the next
 paragraph) shall be included in all copies or substantial portions of the
 Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.

=== Version history

; 0.5.3 : Revert breaking build changes in 0.5.2
; 0.5.2 : Build enhancements
; 0.5.1 : Add a record printer/reader, handle non-fixnum length passed to {{make-c*vector}}
; 0.5 : Optimize performance using fixnum operations and move-memory!, export {{c*vector-body}}
; 0.4 : Fix bugs in {{@vector-fold-right}} and {{@vector-reverse!}}
; 0.3 : Ensure correct result for {{@vector=}} with more than 2 vectors
; 0.2 : Ensure {{start}} and {{end}} arguments to {{copy!}} procedures are optional
; 0.1 : Ported to Chicken Scheme 5