an archived introduction to Standard ML programming language. [mostly lost to the sands of time and bit rot]

The MLton docs include a directory of reference material. Useful links out to a number of Standard ML related stuff. Also some stuff on type theory more generally.

Standard ML is a programming language which combines the elegance of functional programming with the effectiveness of imperative programming. This tutorial introduces important concepts in the language, illustrating them with brief examples. The examples are suitable for cutting-and-pasting into an on-line session.

Textbook on Standard ML (PDF)

S-expressions are great, but if you think carefully, you might notice that S-expressions work as a kind of high-level assembly language on top of which you craft your own data structures. ML, by contrast, offers a powerful tool for expressing data structures directly: the algebraic data type. Don’t let the mathy name worry you; algebraic data types solve real programming problems