Op 2017-08-17, Rustom Mody schreef <rustompm...@gmail.com>: > On Thursday, August 17, 2017 at 6:49:19 AM UTC+5:30, Mok-Kong Shen wrote: >> Am 17.08.2017 um 02:41 schrieb Steve D'Aprano: >> > By reference and by value are not the only two conventions. >> > >> > Perhaps if you go back to the 1950s you might be able to argue that >> > "reference" and "value" are the only two conventions, but >> > alternatives have existed for many decades, since *at least* 1960 >> > when Algol introduced "call by name".
I'm a bit late to this discussion, but pelase allow me to add some (to me at least) fascinating history to this. In 1966, a very influential paper was published: P.J. Landin, "The Next 700 Programming Languages" See: https://www.cs.cmu.edu/~crary/819-f09/Landin66.pdf In this paper, Landin decribes a "family of unimplemented computing languages that is intended to span differences of application area by a unified framework". He calls this language (or family of languages) ISWIM. It is a language with Lisp-like semantics but "Algol-like" (i.e. infix) syntax, dynamically typed, and he introduces the novel idea to have "Indentation, used to indicate program structure." Sounds familiar to anybody? Yep, this is basically proto-Python. Anyway, then there is a later paper (from 1974) by G.D. Plotkin, "Call-by-name, call-by-value and the λ-calculus" (see http://www.sciencedirect.com/science/article/pii/0304397575900171 ). In this paper, Plotkin "examines the old question of the relationship between ISWIM and the λ-calculus, using the distinction between call-by-value and call-by-name." Yep, in 1974, what to call the calling convention of proto-Python was already an "old question". In this paper, Plotkin introduces the λV-calculus, the call-by-value lambda-calculus, to formalize what it is what ISWIM (and Python) are actually doing. This paper is, to the best of my knowledge, the closest thing to an "official" definition of what call-by-value actually means. Needless to say, according to the definition in Plotkin's paper, Python is "call-by-value". Stephan -- https://mail.python.org/mailman/listinfo/python-list
