121 lines
4.2 KiB
Markdown
121 lines
4.2 KiB
Markdown
# Benz
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Benz is a super tiny scheme interpreter intended to be embedded in other applications such as game engine and network server. It provides a subset language of R7RS with several useful extensions. By default, Benz just contains some C files and headers and this README file. In embedding, you only need to copy the files into the project and add `include` dir to the include path.
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Originally, Benz used to be the core component of [Picrin Scheme](https://github.com/picrin-scheme/picrin). They are currently maintained at separate repositories.
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## Example
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```c
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#include <stdio.h>
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#include "picrin.h"
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/* Simple REPL program */
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int
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main(int argc, char *argv[])
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{
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pic_state *pic;
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pic_value expr;
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pic = pic_open(argc, argv, NULL);
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while (1) {
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printf("> ");
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expr = pic_read(pic, pic_stdin(pic));
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if (pic_eof_p(expr)) {
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break;
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}
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pic_printf(pic, "~s\n", pic_eval(pic, expr, pic->lib));
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}
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pic_close(pic);
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return 0;
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}
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```
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## More Example
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Function binding is also easy. `pic_defun` defines a scheme procedure converting from a C function. In the native function, callee arguments can be taken with `pic_get_args`. `pic_get_args` gets arguments according to the format string. If actual arguments does not match a number or incompatible types, it will raise an exception.
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```c
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#include "picrin.h"
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int fact(int i) {
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return i == 1 ? 1 : i * fact(i - 1);
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}
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pic_value factorial(pic_state *pic) {
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int i;
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pic_get_args(pic, "i", &i);
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return pic_int_value(fact(i));
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}
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int
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main(int argc, char *argv[])
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{
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pic_state *pic = pic_open(argc, argv, NULL);
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pic_defun(pic, "fact", factorial); /* define fact procedure */
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pic_load_cstr(pic, "(display (fact 10))");
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pic_close(pic);
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return 0;
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}
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```
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## Language
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All procedures and syntaces are exported from a single library named `(picrin base)`. The complete list is found at https://gist.github.com/wasabiz/344d802a2340d1f734b7 .
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### call/cc
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Full continuation has many problems in embbeding into applications. By default, Benz's call/cc operator does not support continuation that can handle re-entering (it only supports escape continuations). To remove this restriction, please use an add-on provided from [Picrin Scheme's repository](https://github.com/picrin-scheme/picrin/tree/master/contrib/03.callcc).
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### Strings
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Benz utilize rope data structure to implement string type. Thanks to the implementation, string-append is guaranteed to be done in a constant time (so do string-copy, when ascii-only mode is enabled). In return for that, strings in benz are immutable by default. It does not provide mutation API (string-set!, string-copy! and string-fill! in R7RS). This restriction can be also removed with an add-on in [Picrin Scheme's repository](https://github.com/picrin-scheme/picrin/tree/master/contrib/03.mutable-string).
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### Dictionaries
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Dictionary is a hash table object. Its equivalence is tested with equal? procedure.
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### Attribute
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Benz has an facility to get or set metadata to any heap object.
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## Authors
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See https://github.com/picrin-scheme/benz and https://github.com/picrin-scheme/picrin for details.
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## LICENSE
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Copyright (c) 2013-2014 Yuichi Nishiwaki and other picrin contributors
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Permission is hereby granted, free of charge, to any person obtaining a copy of
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this software and associated documentation files (the "Software"), to deal in
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the Software without restriction, including without limitation the rights to
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use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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the Software, and to permit persons to whom the Software is furnished to do so,
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subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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