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Forth is an imperative stack-based computer programming language and environment originally designed by Charles "Chuck" Moore. Language features include structured programming, reflection (the ability to modify the program structure during program execution), concatenative programming (functions are composed with juxtaposition) and extensibility (the programmer can create new commands). Although not an acronym, the language's name is sometimes spelled with all capital letters as FORTH, following the customary usage during its earlier years. A procedural programming language without type checking, Forth features both interactive execution of commands (making it suitable as a shell for systems that lack a more formal operating system) and the ability to compile sequences of commands for later execution. Some Forth implementations (usually early versions or those written to be extremely portable) compile threaded code, but many implementations today generate optimized machine code like other language compilers. Forth is used in the Open Firmware boot loader, space applications,〔(NASA applications of Forth ) (original NASA server no longer running, copy from archive.org)〕 and other embedded systems which involve interaction with hardware. The bestselling 1986 MS-DOS game Starflight, from Electronic Arts, was written with a custom Forth. The open source Gforth implementation is actively maintained, as are several commercially supported systems. ==Overview== A Forth environment combines the compiler with an interactive shell, where the user defines and runs subroutines called "words". Words can be tested, redefined, and debugged as the source is entered without recompiling or restarting the whole program. All syntactic elements, including variables and basic operators are defined as words. Forth environments vary in how the resulting program is stored, but ideally running the program has the same effect as manually re-entering the source. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Forth (programming language)」の詳細全文を読む スポンサード リンク
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