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APL2C: Difference between revisions
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'''APL2C''' is a [[Nested array model|nested]] APL implementation consisting of a complete interpreter, and a compatible compiler with some restrictions. It supports much of the functionality specified by the Extended APL standard [[ISO/IEC 13751:2001]], including some features such as the [[Commute]] and [[Rank (operator)|Rank]] operators that were not widely supported at the time of its initial release.<ref>F.H.D. van Batenburg. [http://archive.vector.org.uk/art10000930 Conformity of APL Implementations to the ISO APL Standard]. [[Vector journal]] Volume 21, No.3. 2005-05.</ref> Development of APL2C began in 1991, and it was used in commercial applications before its public release. The compiler and its use in medical image analysis were presented at the [[APL00|2000 APL conference]].<ref>Tilman P. Otto. [https://doi.org/10.1145/570475.570498 APL Based medical image analysis] at [[APL00]].</ref><ref>Tilman P. Otto. [https://doi.org/10.1145/570475.570499 An APL Compiler] at [[APL00]].</ref> The implementation was later offered as a trial version, with a tutorial on using it presented at the 2001 APL conference. | '''APL2C''' is a [[Nested array model|nested]] APL implementation consisting of a complete interpreter, and a compatible compiler with some restrictions. It supports much of the functionality specified by the Extended APL standard [[ISO/IEC 13751:2001]], including some features such as the [[Commute]] and [[Rank (operator)|Rank]] operators that were not widely supported at the time of its initial release.<ref>F.H.D. van Batenburg. [http://archive.vector.org.uk/art10000930 Conformity of APL Implementations to the ISO APL Standard]. [[Vector journal]] Volume 21, No.3. 2005-05.</ref> Development of APL2C began in 1991, and it was used in commercial applications before its public release. The compiler and its use in medical image analysis were presented at the [[APL00|2000 APL conference]].<ref>Tilman P. Otto. [https://doi.org/10.1145/570475.570498 APL Based medical image analysis] at [[APL00]].</ref><ref>Tilman P. Otto. [https://doi.org/10.1145/570475.570499 An APL Compiler] at [[APL00]].</ref> The implementation was later offered as a trial version, with a tutorial on using it presented at the 2001 APL conference. | ||
APL2C's compiler generates [[wikipedia:C_(programming_language)|C]] code that calls functions for primitives and other operations such as loading variables, removing interpreter dispatch overhead. Compiling allows a program to be distributed as an executable file, and allows the APL code to inter-operate with C. | APL2C's compiler generates [[wikipedia:C_(programming_language)|C]] code that calls functions for primitives and other operations such as loading variables, removing interpreter dispatch overhead. Compiling allows a program to be distributed as an executable file, and allows the APL code to inter-operate with C. In order to compile, the generated code must be linked against a platform-specific [[wikipedia:shared library|shared library]] containing primitive implementations, as source code for the primitives is not distributed. Some dynamic functionality is also restricted: compiled programs can't dynamically create APL functions with <syntaxhighlight lang=apl inline>⎕FX</syntaxhighlight>, and can't pass arrays (rather than functions) as [[operand]]s to user-defined operators. | ||
== Control structures == | |||
[[Control structure]]s in APL2C are written using the [[Del]] character <syntaxhighlight lang=apl inline>∇</syntaxhighlight>, which is not used for [[defined function|function definition]] because this is initiated with editor interaction rather than source code. All control structures consist of an opening <syntaxhighlight lang=apl inline>∇</syntaxhighlight> followed by an expression, and closed with <syntaxhighlight lang=apl inline>∇</syntaxhighlight> alone. For example, the following structure doubles <syntaxhighlight lang=apl inline>X</syntaxhighlight> if it's less than 3. | |||
<syntaxhighlight lang=apl> | |||
∇X<3 | |||
X←2×X | |||
∇ | |||
</syntaxhighlight> | |||
The interpretation of the control expression's result follows a proposal of F.H.D. van Batenburg.<ref>F. H. D. van Batenburg. [https://dl.acm.org/doi/10.1145/114054.114092 L-one-two-three (L1:..L2:..L3:) considered harmful] at [[APL91]].</ref> If the result is a non-negative number, the enclosed code is repeated that many times. A negative number indicates to repeat a number of times equal to the absolute value, but return to the controlling expression afterwards, allowing "while" to be implemented. A vector indicates counts for multiple sections, which are each preceded with a label-less <syntaxhighlight lang=apl inline>:</syntaxhighlight>, allowing "if-else" and "select" forms. | |||
== References == | == References == | ||
<references/> | <references/> | ||
{{APL dialects}}[[Category:APL dialects]][[Category:Nested array languages]][[Category:Ahead-of-time compilers]] | {{APL dialects}}[[Category:APL dialects]][[Category:Nested array languages]][[Category:Ahead-of-time compilers]] | ||