发布于 2014-11-03 23:21:29 | 258 次阅读 | 评论: 0 | 来源: 网友投递
Kawa 高级动态编程语言
Kawa是一门编程语言，用JAVA实现的高级语言，编译出来是JAVA的字节码，在文件系统中，就是.class文件。
Kawa 是一个采用 Java 实现的高级动态编程语言，编译后是 Java 的类。
Kawa 1.90 是个 beta 版本，很快将会发布 Kawa 2.0 版本，此版本包括大量的新特性，最值得关注的是 R7RS 兼容性。
改进记录如下：
New define-alias can define aliases for static class members.
The treatment of keywords is changing to not be self-evaluating (in Scheme). If you want a literal keyword, you should quote it. Unquoted keywords should only be used for keyword arguments. (This will be enforced in a future release.) The compiler now warns about badly formed keyword arguments, for example if a value is missing following a keyword.
The default is now Java 7, rather than Java 6. This means the checked-in source code is pre-processed for Java 7, and future binary releases will require Java 7.
The behavior of parameters and fluid variables has changed. Setting a parameter no longer changes its value in already-running sub-threads. The implementation is simpler and should be more efficient.
The form define-early-constant is similar todefine-constant, but it is evaluated in a module's class initializer (or constructor in the case of a non-static definition).
Almost all of R7RS is now working:
The various standard libraries such as (scheme base) are implemented.
The functions eval and loadcan now take an environment-specifier. Implemented the environment function.
Extended numerator,denominator, gcd, and lcm to inexacts.
Implemented the define-library syntax.
More pieces of R7RS-style library functionality are working: The keyword export is now a synonym for module-export, and both support the rename keyword. The prefix option of import now works.
The cond-expand form now supports thelibrary clause.
Implemented make-promise and delay-force(equivalent to the older name lazy).
Implemented include-ci. The command includenew searches search the containing file's directory. It does this aftersearching the current directory, for backward compatibility.
Implemented define-values.
Fixed string->number to correctly handle a radix specifier in the string.
The read procedure now returns mutable pairs.
If you need to use ... in a syntax-rulestemplate you can use (...template), which disables the special meaning of ... in template. (This is an extension of the older (... ...).)
Alternatively, you can can write(syntax-rulesdots(literals)rules). The symbol dots replaces the functionality of... in the rules.
An underscore _ in a syntax-rules pattern matches anything, and is ignored.
The syntax-error syntax (renamed from %syntax-error) allows error reporting insyntax-rules macros. (The older Kawa-specific syntax-error procedure was renamed to report-syntax-error.)
Implemented and documented R7RS exception handling: The syntax guard and the procedures with-exception-handler,raise, and raise-continuable all work. The error procedure is R7RS-compatible, and the procedures error-object?, error-object-message,error-object-irritants, file-error?, and read-error? were implemented.
Implemented emergency-exit, and modified exitso finally-blocks are executed.
Implemented exact-integer?, floor/,floor-quotient, floor-remainder,truncate/, truncate-quotient, and truncate-remainder.
The letrec* syntax is now supported. (It works the same as letrec, which is an allowed extension of letrec.)
The functions utf8->stringand string->utf8 are now documented in the manual.
The changes to characters and strings are worth covering separately:
The character type is now a new primitive type (implemented as int). This can avoid boxing (object allocation)
There is also a new character-or-eof. (A union of character and the EOF value, except the latter is encoded as -1, thus avoiding object allocation.) The functions read-char and peek-char now return a character-or-eof value.
Functions like string-ref that take a character index would not take into account non-BMP characters (those whose value is greater than #xffff, thus requiring two surrogate characters). This was contrary to R6RS/R7RS. This has been fixed, though at some performance cost . (For example string-ref andstring-length are no longer constant-time.)
Implemented a string-cursor API (based on Chibi Scheme). Thes allow efficient indexing, based on opaque cursors (actually counts of 16-bits chars).
Optimized string-for-each, which is now the preferred way to iterate through a string.
Implemented string-map.
New function string-append! for in-place appending to a mutable string.
New function string-replace! for replacing a substring of a string with some other string.
The SRFI-13 function string-append/sharedis no longer automatically visible; you have to(import (srfi :13 strings)) or similar.
The module-name form allows the name to be a list, as in a R6RS/R7RS-style library name.
The syntax @expression is a splicing form. The expression must evaluate to a sequence (vector, list, array, etc). The function application or constructor form is equivalent to all the elements of the sequence.
The parameter object current-path returns (or sets) the default directory of the current thread.
Add convenience procedures and syntax for working with processes:run-process, process-exit-wait,process-exit-ok?, &cmd, &`,&sh, path-bytes, and path-data. Convenient syntax for re-direction: &<{pname} &>{pname} &>>{pname}. Read about processes. We also introduce "blobs" which may be text or binary depending on context.
The initial values of (current-output-port)and (current-error-port) are now hybrid textual/binary ports. This means you can call write-bytevectorand write-u8 on them, making it possible for an application to write binary data to standard output. Similarly, initial value of (current-input-port)is a hybrid textual/binary port, but only if there is no console (standard input is not a tty).
The cond-expand features java-6though java-9 are now set based on theSystem property "java.version"(rather than how Kawa was configured).
An Emacs-style coding declaration allows you to specify the encoding of a Scheme source file.
The command-line option --debug-syntax-pattern-matchprints logging importation to standard error when a syntax-rulesor syntax-case pattern matches.
SRFI-60 (Integers as Bits) is now fully implemented.
Ported SRFI-101. These are immutable (read-only) lists with fast (logarithmic) indexing and functional update (i.e. return a modified list). These are implemented by a RAPair class which extends the generic pair type, which means that most code that expects a standard list will work on these lists as well.
The class kawa.lib.kawa.expressionscontains an experimental Scheme API for manipulating and validating expressions.
Internal: Changed representation used for multiple values to an abstract class with multiple implementations.
Internal: Started converting to more standard Java code formatting and indentation conventions, rather than GNU conventions. Some files converted; this is ongoing work.
Internal: Various I/O-related classes moved to new package gnu.kawa.io.
Various changes to the configure+make build framework: A C compiler is now only needed if you configure with--enable-kawa-frontend. Improved support for building under Windows (using MinGW/MSYS).
Support for building with GCJ was removed.