History of the Scheme programming language: Difference between revisions

Revision as of 21:47, 10 March 2025

Revision as of 21:47, 10 March 2025

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[[ALGOL 58]], originally to be called IAL for "International Algorithmic Language", was developed jointly by a committee of European and American computer scientists in a meeting in 1958 at [[ETH Zurich]]. [[ALGOL 60]], a later revision developed at the ALGOL 60 meeting in Paris and now commonly named [[ALGOL]], became the standard for the publication of algorithms and had a profound effect on future language development, despite the language's lack of commercial success and its limitations. [[Tony Hoare]] has remarked: "Here is a language so far ahead of its time that it was not only an improvement on its predecessors but also on nearly all its successors."<ref>{{cite book |last=Hoare |first=Tony |author-link=Tony Hoare |date=December 1973 |title=Hints on Programming Language Design |url=http://www.eecs.umich.edu/~bchandra/courses/papers/Hoare_Hints.pdf |page=27 }} (This statement is sometimes erroneously attributed to [[Edsger W. Dijkstra]], also involved in implementing the first ALGOL 60 [[compiler]].)</ref>

ALGOL introduced the use of block structure and lexical scope. It was also notorious for its difficult [[call by name]] default parameter passing mechanism, which was defined so as to require textual substitution of the expression representing the working parameter in place of the formal parameter during execution of a procedure or function, causing it to be re-evaluated each time it is referenced during execution. ALGOL implementors developed a mechanism they called a [[thunk]], which captured the context of the working parameter, enabling it to be evaluated during execution of the procedure or function.

==Carl Hewitt, the Actor model, and the birth of Scheme==

{{See also|Actor model|Planner (programming language)|MDL (programming language)}}

In 1971 Sussman, [[Drew McDermott]], and [[Eugene Charniak]] had developed a system called [[Planner (programming language)#Micro-planner implementation|Micro-Planner]] which was a partial and somewhat unsatisfactory implementation of [[Carl Hewitt]]'s ambitious [[Planner (programming language)|Planner]] project. Sussman and Hewitt worked together along with others on Muddle, later renamed [[MDL (programming language)|MDL]], an extended Lisp which formed a component of Hewitt's project. Drew McDermott, and Sussman in 1972 developed the Lisp-based language ''Conniver'', which revised the use of automatic backtracking in Planner which they thought was unproductive. Hewitt was dubious that the "hairy control structure" in Conniver was a solution to the problems with Planner. [[Pat Hayes]] remarked: "Their [Sussman and McDermott] solution, to give the user access to the implementation primitives of Planner, is however, something of a retrograde step (what are Conniver's semantics?)"<ref>{{cite journal |last=Hayes |first=Pat |date=1974 |title=Some Problems and Non-Problems in Representation Theory |journal=Society for the Study of Artificial Intelligence and the Simulation of Behaviour (AISB) }}</ref>

In November 1972, Hewitt and his students invented the [[Actor model]] of computation as a solution to the problems with Planner.<ref name="hewitt1973">{{cite journal |last1=Hewitt |first1=Carl |author-link=Carl Hewitt |last2=Bishop |first2=Peter |last3=Steiger |first3=Richard |title=A Universal Modular Actor Formalism for Artificial Intelligence |publisher=IJCAI |year=1973}}</ref> A partial implementation of Actors was developed called Planner-73 (later called PLASMA). Steele, then a graduate student at MIT, had been following these developments, and he and Sussman decided to implement a version of the Actor model in their own "tiny Lisp" developed on [[Maclisp]], to understand the model better. Using this basis they then began to develop mechanisms for creating actors and sending messages.<ref name="revisited">{{cite journal

|last1=Sussman |first1=Gerald Jay |author-link=Gerald Jay Sussman |last2=Steele Jr. |first2=Guy L. |author-link2=Guy L. Steele Jr.

|date = December 1998