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Programming Language Theory: Difference between revisions
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==Typing== | ==Typing== | ||
Weak- vs strong-typing refers to the degree to which the language's typing system can be subverted, and whether this is regularly necessary. Static- vs dynamic-typing refers to (among other possible definitions) whether type is determined at compile-time or run-time. The benefits of static typing include: | Weak- vs strong-typing refers to the degree to which the language's typing system can be subverted, and whether this is regularly necessary. Static- vs dynamic-typing refers to (among other possible definitions) whether type is determined at compile-time or run-time (among dynamic typing, ''duck typing'' types based on (dynamically-bound) method availability). The benefits of static typing include: | ||
* Detection of many types of errors at compile-time | * Detection of many types of errors at compile-time | ||
** "Safety = Progress + Preservation" (Harper 1994) suggests well-typed expressions ought not get [[Programming_Language_Theory#Divergent_Combinators|stuck]], and that reductions of well-typed expressions are themselves well-typed. | ** "Safety = Progress + Preservation" (Harper 1994) suggests well-typed expressions ought not get [[Programming_Language_Theory#Divergent_Combinators|stuck]], and that reductions of well-typed expressions are themselves well-typed. | ||
* Improved performance, reduced resource requirements | * Improved performance, reduced resource requirements | ||
* Secure data abstractions can be built atop the safety of strong typing systems | * Secure data abstractions can be built atop the safety of strong typing systems | ||
Properties of a typing system include: | |||
* Support for ''polymorphism'' (dispatch based on types of actual arguments) | |||
** Parametric polymorphism: Generation of a version for necessary types (Ada generics, C++ templates, SML type parameters) | |||
==Objects== | ==Objects== | ||
