R7RS Scheme specification:
I have often used (slib format) for formatting text, which is borrowed from
Lisp. This library provides a scheme-like way of formatting text. (Note:
the Tangerine Edition refers to SRFI 159, but that has been withdrawn in
favour of SRFI 166.)
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R7RS Name
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Documentation
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Description
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(scheme show)
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(srfi 159)
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Formatting text
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I have used Dorai Sitaram's pregexp library
in the past, which uses a familiar string-based representation of
regular-expressions. This library, like show, provides a scheme-like way of
describing regular expressions.
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R7RS Name
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Documentation
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Description
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(scheme regex)
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(srfi 115)
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Regular expressions
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- Text
- This library introduces an immutable form of a string, called a
text.
The rationale for this library is that more efficient operations can be
implemented for strings which are immutable, particularly if they are
unicode-encoded. Helpfully, many of the implemented operations work on
"textual" objects, which includes both the new immutable text data type and
regular string values.
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R7RS Name
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Documentation
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Description
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(scheme text)
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(srfi 135)
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Immutable strings
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- Numbers
- These libraries provide additional functionality and potentially efficient implementations for working with numbers.
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R7RS Name
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Documentation
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Description
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(scheme division)
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(srfi 141)
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Provides six different ways of computing the quotient and remainder (q and r) when dividing an integer n so that n = dq+r
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(scheme bitwise)
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(srfi 151)
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Treats integers as twos-complement numbers, and provides a complete set of operators for manipulating integers in bitwise form
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(scheme fixnum)
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(srfi 143)
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Provides efficient implementations of operations on integers which are "small enough" to be treated within a single machine word
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(scheme flonum)
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(srfi 144)
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Provides efficient implementations of operations on flonums, a subset of the full range of inexact real numbers
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Data structures (collections) seem to have been a major focus of R7RS-large
development. The small language has built-in the list and vector datatypes, a
specialisation of vector to bytevectors, and a simple mapping pattern in the
form of association lists.
- Set-like
- Designed to hold one or more values without any additional structure, such as order, imposed on them. Set-like structures may enforce unique values (sets) or permit multiple values (bags, or multi-sets).
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R7RS Name
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Documentation
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Description
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(scheme box)
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(srfi 111)
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Provides a single-item container
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(scheme set)
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(srfi 113)
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Provides both set and bag data structures, along with a wide-range of supporting functions
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(scheme charset)
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(srfi 14)
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Deals specifically with sets of characters, making available some predefined character sets, and operations to work with such sets
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- List-like
- Designed to hold one or more values in a specific order. Values can be duplicated within the data structure.
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R7RS Name
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Documentation
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Description
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(scheme list)
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(srfi 1)
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Provides a wide-range of functions working with the built-in list datatype
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(scheme ilist)
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(srfi 116)
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Provides an immutable version of the built-in list along with functions equivalent to those in the list library, where appropriate
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(scheme rlist)
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(srfi 101)
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An alternative to the built-in list, but offers more efficient references (rlist-ref is O(log n)) and a functional interface. Note that, unlike the SRFI and implementation in Gauche, the R7RS-large version prefixes identifiers with "r" to avoid name-clashes with list
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(scheme ideque)
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(srfi 134)
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Provides an immutable deque data struture, a double-ended queue which supports efficient (O(1)) adding/removal of items from either end
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(scheme list-queue)
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(srfi 117)
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A mutable deque data structure, which offers efficient adding/removal of items from the front and adding of items to the back
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Vectors are a variant of lists, which both hold values in a specific order, but
also provide O(1) look-up time using a numeric index. The different types allow
for specialisation in terms of the particular contents.
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R7RS Name
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Documentation
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Description
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(scheme vector)
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(srfi 133)
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Provides a wide-range of functions working with the built-in vector datatype
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(scheme bytevector)
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(rnrs bytevectors)
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Taken from R6RS
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(scheme vector @)
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(srfi 160)
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Provide homogeneous equivalents to the vector type and library for specific numeric types; these can potentially be implemented more efficiently than the general form
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- Map-like
- Collections of key-value pairs, where a key is used to retrieve a value stored within the collection. They can be thought of as a generalisation of the vector, except that any type of value can be used as the index, not just a number.
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R7RS Name
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Documentation
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Description
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(scheme hash-table)
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(srfi 125)
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Provides a standard hash table data structure
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(scheme mapping)
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(srfi 146)
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Provides a more general data structure than hash-table, supporting functional procedures
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- Stream-like
- These data structures do not store existing values, but instead construct new values on demand.
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R7RS Name
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Documentation
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Description
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(scheme generator)
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(srfi 158)
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Provides both "generators" and "accumulators". A generator is a zero-argument procedure that acts as a source of values; an accumulator is a single-argument procedure that acts as a sink of values
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(scheme lseq)
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(srfi 127)
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A list where the "cdr" element is a generator; this is similar to stream except that the lists are odd, so the first element is eager evaluated
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(scheme stream)
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(srfi 41)
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Provides low-level and higher-level support for lazy lists; lists where each item is constructed on demand. These lists are even, so both elements are lazy evaluated
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These libraries are used to support data structures.
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R7RS Name
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Documentation
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Description
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(scheme comparator)
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(srfi 128)
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Bundles together the equality, comparison and hash functions for different data-types, so they can be used in the construction of a data structure for a specific type of data. This library is used in: hash-table, mapping, and set
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(scheme ephemeron)
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(srfi 124)
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Can be used to implement data structures with weak references, which permit garbage collection
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(scheme sort)
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(srfi 132)
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A collection of sort, merge and related functions, working on the built-in list and vector datatypes
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This edition appears to have been
voted on, but there are not many details available yet, e.g. what the `(scheme
NAME)` names will be. Here is a list of what might be expected:
R6RS includes several libraries, which I've tabulated below for easy reference.
R7RS-large has gradually included a number of approximately equivalent
libraries, so I've listed these to make it easy to link the two standards -
"equivalent" is meant loosely, as there are many variations and even
incompatibilities.
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R6RS Name
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Description
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R7RS Equivalent
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(rnrs unicode)
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Unicode semantics when working with characters and strings.
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Mostly covered in (scheme base) and (scheme char), although full Unicode support is optional
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(rnrs bytevectors)
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Deals with blocks of binary data.
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(scheme bytevector) included in R7RS-large (Tangerine)
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(rnrs lists)
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Useful procedures that operate on lists.
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Anything not in (scheme base) is in (scheme list), included in R7RS-large (Red)
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(rnrs sorting)
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Provides list-sort and vector-sort.
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(scheme sort) included in R7RS-large (Red)
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(rnrs control)
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Useful control structures (e.g. when, do).
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Included in (scheme base)
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(rnrs records *)
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Record data-types.
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An alternative form of record is included in (scheme base)
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(rnrs exceptions)
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Exception handling and exception-raising constructs.
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Included in (scheme base)
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(rnrs conditions)
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For creating and inspecting condition types and values.
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-
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(rnrs io *)
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For performing input and output.
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Some support in (scheme base) and (scheme file)
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(rnrs files)
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Provides file-exists? and delete-file.
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Included in (scheme file)
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(rnrs programs)
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Provides command-line and exit.
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Included in (scheme process-context)
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(rnrs arithmetic fixnums)
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Various operations on fixnums.
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(scheme fixnum) included in R7RS-large (Tangerine)
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(rnrs arithmetic flonums)
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Various operations on flonums.
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(scheme flonum) included in R7RS-large (Tangerine)
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(rnrs arithmetic bitwise)
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Generic operations on exact integer objects.
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(scheme bitwise) included in R7RS-large (Tangerine)
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(rnrs syntax-case)
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Support for writing low-level macros in a high-level style.
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Included in R7RS-large (Yellow)
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(rnrs hashtables)
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Operations for creating and using hashtables.
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(scheme hash-table) included in R7RS-large (Red)
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(rnrs enums)
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Enumerated values and enumerated sets.
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- Although (srfi 209) is scheduled for vote in R7RS-large (Orange).
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Considering the levels of R7RS-large support in the implementations I use:
- Gauche
- complete support.
- Kawa
- partial support with r7rs-libs. Kawa's implementation of continuations - see internals/complications - means
(scheme generator) and (scheme lseq) cannot be supported.
- Sagittarius
- complete support.
- Gauche
- complete support.
- Kawa
- partial support with r7rs-libs. Missing are
(scheme show) (scheme regex) (scheme fixnum) (scheme flonum) (scheme bytevector) (scheme vector @) (scheme mapping)
- Sagittarius
- complete support, except that
(scheme show) is named (scheme format).
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Library Name
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Description
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Gauche
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Kawa
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Sagittarius
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syntax-case
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From R6RS
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-
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-
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Y
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identifier-case
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From R6RS
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-
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-
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Y
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(srfi 139)
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Syntax parameters
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-
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-
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Y
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(srfi 188)
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Splicing binding constructs for syntactic keywords
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-
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-
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-
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(srfi 212)
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Aliases
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-
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see define-alias
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-
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(srfi 213
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Identifier properties
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-
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-
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-
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(srfi 61)
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A more general cond clause
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built-in
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-
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Y
|
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(srfi 8)
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receive: Binding to multiple values
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Y
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Y
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Y
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(srfi 31)
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A special form rec for recursive evaluation
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Y
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r7rs-libs
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Y
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(srfi 26)
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Notation for specializing parameters without currying
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Y
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Y
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Y
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(srfi 219)
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Define higher-order lambda
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Y
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-
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built-in
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(srfi 210)
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Procedures and syntax for multiple values
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r7rs-libs
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r7rs-libs
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r7rs-libs
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