Editing APL (programming language) (section)

=== Optimised bytecode ===
Weak typing in APL means that a name may reference an array (of any datatype), a function or an operator. In general, the interpreter cannot know in advance which form it will be and must therefore perform analysis, syntax checking etc. at run-time.<ref>{{cite journal |last1=Strawn |first1=George O. |date=March 1977 |title=Does APL really need run-time parsing? |journal=Software: Practice and Experience |volume=7 |issue=2 |pages=193–200 |doi=10.1002/spe.4380070207 |s2cid=1463012}}</ref> However, in certain circumstances, it is possible to deduce in advance what type a name is expected to reference and then generate [[bytecode]] which can be executed with reduced run-time overhead. This bytecode can also be optimised using compilation techniques such as [[constant folding]] or [[common subexpression elimination]].<ref name="DyalogCompiler">{{cite web|title=Compiler User Guide|url=http://docs.dyalog.com/16.0/Compiler%20User%20Guide.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://docs.dyalog.com/16.0/Compiler%20User%20Guide.pdf |archive-date=2022-10-09 |url-status=live |website=www.dyalog.com|publisher=Dyalog Ltd.|access-date=May 7, 2018}}</ref> The interpreter will execute the bytecode when present and when any assumptions which have been made are met. Dyalog APL includes support for optimised bytecode.<ref name="DyalogCompiler"/>