Comment by doall | Hacker News Reader

Comment by doall | Hacker News Reader

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http://jmc.stanford.edu/articles/lisp/lisp.pdf

"One mathematical consideration that influenced LISP was to express programs as applicative expressions built up from variables and constants using functions. I considered it important to make these expressions obey the usual mathematical laws allowing replacement of expressions by expressions giving the same value. The motive was to allow proofs of properties of programs using ordinary mathematical methods. This is only possible to the extent that side-effects can be avoided. Unfortunately, side-effects are often a great convenience when computational efficiency is important, and “functions” with side-effects are present in LISP."

Seems not black or white to me. This paper is also written by McCarthy. He had pureness in his mind, but the real implementation had side-effects for practical reasons.

>McCarthy's original conception of Lisp was not purely functional (according to McCarthy himself as well as the historical evidence)

Again not black or white (according to McCarthy himself). The pure language is written in the original LISP paper and Graham and I viewed it as the core and it also showed the pureness of LISP.

>so how would the purely functional subset described in a later paper be "the original LISP" if you aren't denying the earlier work?

Again the definition. I have already explained what I meant with "the original LISP".

> > so how would the purely functional subset described in a later paper be "the original LISP" if you aren't denying the earlier work?

> Again the definition. I have already explained what I meant with "the original LISP".

I didn't ask what you meant by it, I asked how using that definition is different from claiming that McCarthy's earlier work on Lisp wasn't Lisp. In the same paper you just quoted, McCarthy says that Lisp was planned to have sequential programs before it was planned to have recursive functions; the part you quoted does not say that destructive functions were added later or that he ever planned not to have them. In the 1958 paper, he was already describing a language with mutable objects.

>McCarthy's earlier work on Lisp wasn't Lisp.

I didn't say this. I have already explained about the difference between the first LISP implementation and the core language written in the 1960 paper. There is no one true definition of LISP and I have already talked about this. People have different views of what LISP is.

You said black and white and it is not true from the paper I have shown.

>In the 1958 paper, he was already describing a language with mutable objects.

I am not talking about the 1958 paper. I am not also talking about which idea is first or not. Since it is not written clearly in the papers shown so far which idea is first, but I have showed that it is not black or white. Graham and my claim is based on the so called "original LISP paper" in 1960 and the pure version of LISP is written in it.

You and I have different views of LISP and that is OK. But please don't force your view to us, since there is no one true definition or interpretation of LISP.

Herbert Stoyan researched about the early history of Lisp and wrote books about that.

https://github.com/papers-we-love/papers-we-love/blob/master...

He says:

> LISP is understood as the model of a functional programming language today. There are people who believe that there once was a clean "pure" language design in the functional direction which was comprised by AI-programmers in search of efficiency. This view does not take into account, that around the end of the fifties, nobody, including McCarthy himself, seriously based his programming on the concept of mathematical function. It is quite certain that McCarthy for a long time associated programming with the design of stepwise executed "algorithms".

> On the other side, it was McCarthy who, as the first, seemed to have developed the idea of using funtional terms (in the form of "function calls" or "subroutine calls") for every partial step of a program. This idea emerged more as a stylistic decision, proved to be sound and became the basis for a proper way of programming - functional progamming (or, as I prefer to call it, function-oriented programming). We should mention here that McCarthy at the same time conceived the idea of logic-oriented programming, that is, the idea of using logical formulae to express goals that a program should try to establish and of using the prover as programming language interpreter. To come back to functional programming, it is an important fact that McCarthy as mathematician was familiar with some formal mathematical languages but did not have a deep, intimate understanding of all their details. McCarthy himself has stressed this fact (23). His aim was to use the mathematical formalismus as languages and not as calculi. This is the root of the historical fact that he never took the Lambda-Calculus conversion rules as a sound basis for LISP implementation. We have to bear this in mind if we follow now the sequence of events that led to LISP. It is due to McCarthy's work that functional programming is a usable way of programming today. The main practice of this programming style, done with LISP, still shows his personal mark.

Thanks for an interesting reference. This seems to be an important paper and I would like to take time later and read it in more depth.

> >McCarthy's earlier work on Lisp wasn't Lisp.

> I didn't say this.

Again, I was asking how what you did say was different from it. Your answer seems to just be that your definition of Lisp means the subset described in the 1960 paper, and doesn't include the original implementation or McCarthy's earlier writing on the subject.

> You said black and white and it is not true from the paper I have shown.

The paper you quoted said that Lisp was originally conceived as an impure language (the part I quoted) and that that was unfortunate, but true (the part you quoted).

> I have already explained about the difference between the first LISP implementation and the core language written in the 1960 paper. [...] I am not talking about the 1958 paper.

So you meant to say that the 1960 paper was the first description of a pure language. Calling the 1960 paper's subset of Lisp "the original LISP" and disregarding the already-existing implemented Lisp system which the paper acknowledges, as well as McCarthy's previous writing on the subject, is misleading at best.

> I am not also talking about which idea is first or not.

Then we have different definitions of "original," too.

>Your answer seems to just be that your definition of Lisp means the subset described in the 1960 paper,

Not true. I also consider LISP I as LISP, Common Lisp as LISP, and understand people calling Scheme as LISP, or Clojure as LISP. I really respect all of the works involving the LISP family.

>The paper you quoted said that Lisp was originally conceived as an non-pure language (the part I quoted) and that that was unfortunate, but true (the part you quoted).

The paper is referring LISP to the actual implementation and that is impure as we know. From the part I quoted, he had both pure and non-pure ideas and that I call "not black or white".

>So you meant to say that the 1960 paper was the first description of a pure language.

No I did not say this. Since it is not clear if it is the first pure language or not.

>Calling the 1960 paper's subset of Lisp "the original LISP"

I have already explained what I meant. I will also add that since the 1960 paper is so called "the original LISP paper", and the paper refers to the LISP implementation and describes a pure core LISP, I called the pure part "the original LISP" meaning the core of LISP in the original LISP paper. The most important part is the meaning and since I have explained what I meant, if you are not satisfied with the wordings, just use a different symbol "XXX LISP" and you will be satisfied.

>and disregarding the already-existing implemented Lisp system which the paper acknowledges,

No I am not. You seem to be disregarding that a pure LISP can be constructed from the idea in the paper.

>as well as McCarthy's previous writing on the subject, is misleading at best.

Not true.

Since I have to wait for more than an hour to reply in a deep comment level, I will reply here to kbp.

>The confusion seems to stem from your insistence on using the word "original" to mean the pure Lisp described in the 1960 paper, despite the fact there was Lisp before that. It seems like it's mostly a disagreement about the meaning of the word original; I consider your use misleading.

Yes I should have used a different word and I am sorry for making a confusion. After this long discussion about the history of LISP, I can now come up with a better word instead of using "original", and also I have an updated view of the LISP history.

>As I said several times, The 1960 paper describes a pure subset of Lisp, I was only disagreeing that it was the original Lisp.

Great!

>I think we understand each other now.

Yes it seems so.

>It was nice reading some old papers I hadn't seen before :)

Definitely true and thanks for having a very long discussion :)

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