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Although most attempts to speed-up Smalltalk have focused on providing more efficient interpreters, code optimization is probably necessary for further increases in speed. A type-system for Smalltalk is a prerequisite for building an optimizing compiler. Unfortunately, none of the type-systems so far proposed for Smalltalk are adequate; they either cause nearly all Smalltalk programs to be type incorrect, allow run-time type errors, or do not provide enough information for optimization. This paper presents a type-system for Smalltalk that is suitable for code optimization.
Ralph E. Johnson (Sun,) studied this question.