Smalltalk
Alan Kay and team · 1972
Smalltalk is a pure object-oriented language built for constructionist learning at Xerox PARC in the 1970s. Its first interpreter, Smalltalk-72, was written by Dan Ingalls in about 700 lines of BASIC for the Data General Nova in October 1972. It emerged from Alan Kay’s September 1972 bet that a message-passing core could fit on a page of code—and did so by the eighth morning. Smalltalk-80, released publicly in 1980, introduced foundational OOP ideas, featured an integrated development environment from inception, and established total reflection—both structural and computational. It has no primitive types: all values are objects, and all computation occurs via message passing. ANSI Smalltalk was ratified in 1998.