Standard ML is a type-safe programming language that embodies many innovative ideas in programming language design. It is a statically typedlanguage, with an extensible type system. It supports polymorphic typeinference, which all but eliminates the burden of specifying types of vari-ables and greatly facilitates code re-use. It provides efficient automaticstorage management for data structures and functions. It encourages func-tional (effect-free) programming where appropriate, but allows imperative(effect-ful) programming where necessary. It facilitates programming withrecursive and symbolic data structures by supporting the definition of func-tions by pattern matching. It features an extensible exception mechanismfor handling error conditions and effecting non-local transfers of control.It provides a richly expressive and flexible module system for structur-ing large programs, including mechanisms for enforcing abstraction, im-posing hierarchical structure, and building generic modules. It is portableacross platforms and implementations because it has a precise definition.It provides a portable standard basis library that defines a rich collection ofcommonly-used types and routines.