Type Safety

“Well typed programs cannot go wrong.” — this phrase was coined by Robin Milner in his 1978 paper, A Theory of Type Polymorphism in Programming.

Type safety is the extent to which a programming language discourages or prevents type errors.

Many programs that are syntactically valid but are semantically problematic.

A type error is erroneous or undesirable program behavior caused by a discrepancy between differing data types.

Type enforcement can be static, catching potential errors at compile time or associating type information with values at run-time.