3 ms·

"The input data would be considered the language" really? I would have thought that the question is one of equivalence between a program (not the input) and a

"The input data would be considered the language" really? I would have thought that the question is one of equivalence between a program (not the input) and a language (evaluator) so i read the quoted SICP fragment to mean input --> program --> output and somehow an equivalent input --> (equivalent to program) language evaluator --> output with the "language" (that is evaluated by the evaluator) and "program" being (somehow) "points of view". This seems to posit an equivalence between a program and a language evaluator. Not really disputing your(jacquesm's) formulation, just providing an alternative. I don't completely understand the quoted paragraph either. I find it a little hard to think of a randomly chosen program (say the HN webapp) as a language. The inputs would be submissions, upvotes (clicks), downvotes (clicks)etc. The output would be the display page and scores etc. How is this a language processor? Seems to be one of those "zen koan" elements of SICP, which needs a flash of insight to understand. :-) edited for clarity, (1) responding to jacquesm's response "input -->(equivalent to program)language evaluator" substituted for "input --> language" (2) expanded HN web app example in terms of explicit inputs and outputs

jacquesm 17y ago
the program implements the language, but is not usually written in the language that it implements.
- plinkplonk 17y ago
  "The program implements the language, but is not usually written in the language that it implements." I agree. Edited my formulation to make it more clear.
  - jacquesm 17y ago
    I think the problem is that the abstraction from 'program processes data' to 'program implements language' is a pretty tricky one to get your head around. When you're using stuff like lex+yacc though you quickly realize that almost every processing that you do on structured data of some sort is actually equivalent to implementing a language.

jacquesm 17y ago

the program implements the language, but is not usually written in the language that it implements.

plinkplonk 17y ago
"The program implements the language, but is not usually written in the language that it implements." I agree. Edited my formulation to make it more clear.
- jacquesm 17y ago
  I think the problem is that the abstraction from 'program processes data' to 'program implements language' is a pretty tricky one to get your head around. When you're using stuff like lex+yacc though you quickly realize that almost every processing that you do on structured data of some sort is actually equivalent to implementing a language.