Type Systems
Brief definitions
- Compatibility among composite types describes the behavior of functions applied to data typed similarly to its intended type. Name-based compatibility means that functions work only on data of its intended type and declared subtypes. Property-based compatibility means that functions work on any data that has the same properties as its intended type.
- Type checking determines whether and when types are verified. Static checking occurs at compile-time. Dynamic checking occurs at run-time.
| Language | Type strength | Type safety | Type expression | Type compatibility among composites | Type checking |
|---|---|---|---|---|---|
| ActionScript 3.0 | strong | safe | implicit with optional explicit typing | static | |
| Ada | strong | safe | explicit | name-based | partially dynamic |
| Aldor | strong | unsafe | implicit | static | |
| ALGOL 58 | strong | safe | explicit | static | |
| ALGOL 60 | strong | safe | explicit | static | |
| ALGOL 68 | strong | safe | explicit | property-based | static |
| APL | strong | safe | dynamic | ||
| AutoHotkey | none | ||||
| Ateji PX | strong | safe | explicit | name-based | static |
| BASIC | varies by dialect | ||||
| BLISS | none | n/a | n/a | n/a | n/a |
| BeanShell | strong | safe | name-based | dynamic | |
| Boo | strong | safe | implicit with optional explicit typing | static with optional dynamic typing | |
| C | weak | unsafe | explicit | name-based | static |
| C++ (ISO/IEC 14882) | strong | unsafe | explicit | name-based | static |
| C# | strong | safe | implicit with optional explicit typing | name-based | static |
| Clean | strong | safe | implicit | static | |
| Clojure | strong | safe | implicit with optional explicit typing | dynamic | |
| COBOL | strong | static | |||
| ColdFusion (CFML) | strong | safe | implicit | dynamic | |
| Common Lisp | strong | safe | implicit with optional explicit typing | dynamic | |
| Curl | strong | safe | name-based | ||
| Cython | strong | safe | implicit with optional explicit typing | name-based (extension types) and property-based (Python) | dynamic with optional static typing |
| D | strong | unsafe | explicit | name-based | static |
| Dylan | strong | safe | dynamic | ||
| Eiffel | strong | safe | name-based | static | |
| Erlang | strong | safe | implicit | dynamic | |
| Euphoria | strong | safe | explicit, implicit with objects | name-based | static, dynamic with objects |
| F# | strong | safe | implicit | name-based | static |
| Falcon | strong | safe | implicit | property-based | dynamic |
| Forth | none | n/a | n/a | n/a | n/a |
| Fortran | strong | safe | explicit | name-based | static |
| Gambas | strong | safe | explicit | name-based | |
| GLBasic | strong | safe | explicit. Non-explicit declarations available through project options | name-based | static |
| Go | strong | safe | implicit with optional explicit typing | property-based | static |
| Gosu | strong | safe | partially implicit (local type inference) | name-based (subclassing) and property-based (structural) | static |
| GraphTalk | weak | ||||
| Groovy | strong | safe | implicit with optional explicit typing | dynamic with optional static typing | |
| Harbour | strong | safe | implicit with optional explicit typing | dynamic | |
| Haskell | strong | safe | implicit with optional explicit typing | property-based | static |
| haXe | strong | safe | implicit with optional explicit typing | name-based (subclassing) and property-based (structural) | static with optional dynamic typing |
| Io | strong | safe | implicit | dynamic | |
| ISLISP | strong | safe | dynamic | ||
| J | strong | safe | dynamic | ||
| Java | strong | safe | explicit | name-based | static |
| JavaScript | weak | implicit | dynamic | ||
| Joy | strong | safe | dynamic | ||
| Lua | weak | safe | implicit | dynamic | |
| Mathematica | strong | dynamic | |||
| MATLAB M-code | dynamic | ||||
| Modula-2 | strong | unsafe | explicit | name-based | static |
| Modula-3 | strong | unsafe | explicit | property-based | static |
| Oberon | strong | safe | explicit | name-based | static and partially dynamic |
| Objective-C | weak | safe | explicit | name-based (subclassing) and property-based (protocols) | dynamic with optional static typing |
| OCaml | strong | safe | implicit with optional explicit typing | property-based | static |
| Object Pascal (Delphi) | strong | safe | explicit | name-based | static |
| Opa | strong | safe | implicit with optional explicit typing | property-based | static |
| Oxygene | strong | unsafe | implicit | static | |
| Oz | strong | safe | implicit | property-based | dynamic |
| Pascal | strong | unsafe | explicit | name-based | static |
| Perl 5 | weak | implicit | dynamic | ||
| Perl 6 | partially implicit | dynamic with optional static typing | |||
| PHP | weak | implicit | dynamic | ||
| Plus | strong | safe | explicit | property-based | static, dynamic (optional) |
| Prolog | strong | dynamic | |||
| Pure | dynamic | ||||
| Python | strong | safe | implicit | property-based | dynamic |
| REBOL | strong | safe | implicit | dynamic | |
| RPG (IBM) | strong | unsafe | static | ||
| Ruby | strong | safe | implicit | property-based | dynamic |
| Rust | strong | safe | implicit with optional explicit typing | static with optional dynamic typing | |
| S | strong | dynamic | |||
| S-Lang | strong | safe | implicit | dynamic | |
| Scala | strong | safe | partially implicit (local type inference) | name-based (subclassing) and property-based (structural) | static |
| Scheme | strong | implicit | dynamic (latent) | ||
| Simula | strong | safe | static | ||
| Smalltalk | strong | safe | implicit | dynamic | |
| Standard ML | strong | safe | implicit with optional explicit typing | property-based | static |
| Tcl | dynamic | ||||
| Visual Basic | strong | safe | implicit with optional explicit typing | name-based | static |
| Visual Basic .NET | strong | unsafe | explicit | static | |
| Visual Prolog | strong | safe | partially implicit | name-based | static |
| Windows PowerShell | strong | safe | implicit | dynamic | |
| XL | strong | safe | name-based | static | |
| Language | Type strength | Type safety | Type expression | Type compatibility among composites | Type checking |
Read more about this topic: Comparison Of Programming Languages
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