The Racket repository
2661d46929
Progress toward making the bytecode compiler deterministic, so that a fresh `make base` always produces exactly the same bytecode from the same sources. Most changes involve avoiding hash-table order dependencies and adjusting scope identity. The namespace used to load a reader extension is also better defined. Plus many other little changes. The identity of a scope that is unmarshaled from a bytecode file now incorporates the hash of the file, and the relative order of scopes is preserved in a bytecode file. This combination allows compilation to start with modules that loaded and compiled in different orders (including delayed loading of bytecode fragments within one file). Formerly, a reader extension triggered by `#lang` or `#reader` was loaded in whatever namespace happens to be current. That's unpredictable and can pollute a module build at the level of bytecode. To help make builds deterministic, reader extensions are now loaded in a root namespace of the current namespace. Deterministic compilation in general relies on deterministic macros. The two most common ways for a macro to be non-deterministic are by using `gensym` (use `generate-temporaries`, instead) and by using an unsorted hash-table traversal (don't do that). At this point, bytecode generation is unlikely to be completely deterministic, since I uncovered non-determinism mostly by iterating attempts over the base collections. For now, the intent is not to provide guarantees outside of the compilation of the base collections --- but "more deterministic" is likely to be useful in the short run, and we can improve further in the long run. |
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This is the source code for the main Racket distribution. See "INSTALL.txt" for information on building Racket. License ------- Racket Copyright (c) 2010-2014 PLT Design Inc. Racket is distributed under the GNU Lesser General Public License (LGPL). This implies that you may link Racket into proprietary applications, provided you follow the rules stated in the LGPL. You can also modify Racket; if you distribute a modified version, you must distribute it under the terms of the LGPL, which in particular states that you must release the source code for the modified software. See racket/src/COPYING_LESSER.txt for more information.