Solvent and Game Oriented Assembly Lisp: Difference between pages

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'''Game Oriented Assembly Lisp''' (or '''GOAL''') is a computer game programming language developed by [[Andy Gavin]] and the [[Jak and Daxter]] team at [[Naughty Dog]]. It was written using [[Allegro Common Lisp]] and used in the development of the entire [[Jak and Daxter]] series of games.

[[ja:溶媒]]

Syntactically GOAL resembles [[Scheme (programming language)|Scheme]], though with many idiosyncratic features inspired by other languages such as classes, inheritance, and virtual functions. An example of what GOAL code looks like can be found at [http://lists.midnightryder.com/pipermail/sweng-gamedev-midnightryder.com/2005-August/003804.html]. GOAL encourages an [[imperative programming]] style: programs tend to be comprised of sequence of events to be executed rather than the [[functional programming]] style of functions to be evaluated recursively. This is a diversion from [[Scheme (programming language)|Scheme]], which allows such [[side-effect (computer science)|side-effects]] but does not encourage imperative style.

A '''solvent''' is a liquid that dissolves a [[solute]]. The solvent is the component of a solution that is present in greater amount. See [[solution]].

Like many modern implementations of Common [[Lisp programming language|Lisp]], GOAL does not run in an interpreter, but instead is compiled directly into [[PlayStation 2]] machine code for execution. It offers limited facilities for [[Garbage collection (computer science)|garbage collection]], relying extensively on runtime support. It offers dynamic memory allocation primitives designed to make it well-suited to running in constant memory on a video game console. GOAL has extensive support for [[Inline expansion|inlined]] assembly code using a special <code>rlet</code> form[http://lists.midnightryder.com/pipermail/sweng-gamedev-midnightryder.com/2005-August/003804.html], allowing programmers to freely mix assembly and higher-level constructs within the same function.

Perhaps the most common solvent in everyday life is [[water]]. Many other solvents are organic compounds, such as [[benzene]], [[tetrachloroethylene]] or [[turpentine]].

The GOAL compiler is implemented in [[Allegro Common Lisp]]. It supports a long term compiling listener session which gives the compiler knowledge about the state of the compiled and therefore running program, including the symbol table. This, in addition to dynamic linking, allows a function to be edited, recompiled, uploaded, and inserted into a running game without having to restart. The process is similar to the "edit and continue" feature offered by some [[C++]] compilers, but allows the programmer to replace arbitrary amounts of code (even up to entire object files), and does not interrupt the running game with the debugger. This feature was used to implement code as well as level streaming in the [[Jak and Daxter]] games.

Solvents can be broadly classified into polar and non-polar solvents. Common polar solvents include water and ethanol. Generally polar or ionic compounds will only dissolve in polar solvents. A test for the polarity of a liquid solvent is to rub a plastic rod, to induce static electricity. Then hold this charged rod close to a running stream of the solvent. If the path of the solvent deviates when the rod is held close to it, it is a polar solvent.

GOAL's first use was for the original [[Jak and Daxter]] PS2 game; the predecessor language, GOOL, was also developed by Andy Gavin for [[Crash Bandicoot (video game)|Crash Bandicoot]].

In chemistry, a common rule for determining if a solvent will dissolve a given solute is "like dissolves like." Solvents composed of polar molecules, such as water, dissolve other polar molecules, such as [[table salt]], while nonpolar solvents, such as [[gasoline]], dissolve nonpolar substances such as [[wax]]. The degree that a solvent dissolves a given solute is known as its '''solubility'''. Ethyl alcohol is highly soluble in water, for example. Vinegar is very insoluble in oil, and the two substances will quickly separate into two layers even after being shaken well.

==External links==

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* http://www.franz.com/success/customer_apps/animation_graphics/naughtydog.lhtml &mdash; Franz Inc. success story

* http://bc.tech.coop/blog/060118.html &mdash; Page about LISP developments by [[Paul Graham]] and [[Naughty Dog]]

* http://www.gamasutra.com/features/gdcarchive/2003/White_Stephen.ppt &mdash; (Powerpoint) ''Jak & Daxter: The Precursor Legacy'', development overview, lessons learned, very interesting

* http://www.gamasutra.com/features/gdcarchive/2003/Denman_Stu.ppt &mdash; (Powerpoint) ''Highly detalied continuous worlds'', about the streaming world loader

[[Category:ChemicalsLisp programming language family]]

[[Category:Functional languages]]

[[Category:Object-oriented programming languages]]

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