Type erasure

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In programming languages, type erasure refers to the load-time process by which explicit type annotations are removed from a program, before it is executed at run-time. Operational semantics that do not require programs to be accompanied by types are called type-erasure semantics, to be contrasted with type-passing semantics. The possibility of giving type-erasure semantics is a kind of abstraction principle, ensuring that the run-time execution of a program does not depend on type information. In the context of generic programming, the opposite of type erasure is called reification.[1]

Type inference[edit]

The reverse operation is called type inference. Though type erasure can be used as an easy way to define typing over implicitly typed languages (an implicitly typed term is well-typed if and only if it is the erasure of a well-typed explicitly typed lambda term), it does not always lead to an algorithm to check implicitly typed terms.

See also[edit]


  1. ^ Langer, Angelika. "What is reification?". 
  • Crary, Karl; Weirich, Stephanie; Morrisett, Greg (2002). "Intensional Polymorphism in Type-Erasure Semantics". Journal of Functional Programming. 12 (6): 567–600. doi:10.1017/S0956796801004282.