Standard ML

About Standard ML

fun fib 0 = 0
  | fib 1 = 1
  | fib n = fib (n - 1) + fib (n - 2)

Standard ML (SML) is one of the two main dialects of the ML programming language. ML was the first strong statically typed language, developed in the early 1970s at the University of Edinburgh.

Despite its age, SML feels very young in many ways; SML had features that mainstream languages would not pick up for decades and are still being experimented with today.

Here are some of ML's "cutting-edge" features:

• strong static typing
• automatic type inference
• exception handling
• pattern matching
• parametric polymorphism
• first class functions

SML was originally designed for developping proofs about first-order predicate calculus (read: computer programs) and it can have a distinct academic feel about it.

However, its emphasis on immutability and strong typing has led SML to be used in many fields where program correctness is paramount (compiler design, code analysis, financial systems, medical systems, etc...).

Learning SML makes you a better programmer, because it forces you to write code that is stateless and to use closures effectively.

It's also many programmers first introduction to pattern matching and (truely) strong typing. And because SML's type system is so strong and well-thought out, it often feels like you are working in a dynamically typed language instead.

There are several popular implementations:

• MLton
• SML/NJ
• PolyML.

You can find information on the language on each implementation's sites.