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Lecture 7A: Metacircular Evaluator, Part 1

MIT OpenCourseWare · 31.6K views · 2019-08-22 · 1:24:38

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Overview

Lecture 7A from MIT 6.001 (SICP) by Abelson and Sussman introduces the metacircular evaluator, a Scheme interpreter written in Scheme. It shows how evaluating a program is itself a program.

On Hacker News

HN holds the SICP lectures up as joyful classics, and this lecture as the moment the evaluator is revealed.

Recommended by 1 HN people across 1 months · HN mentions 2020–2023

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Compilers, interpreters & program analysisFunctional programmingUniversity lectures & courses
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What people said

mrspeaker · 2020-06 · Strong recommendation

I re-watch this course every bunch of years, and every time I get something different from it. But mostly it just makes me happy - it's infectious and weird. Especially the "revelation" (spoiler!) [VIDEO]

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ufo · 2023-09 · Reference

"We're getting really close to the spirit of the computer at this point, so I have to show a certain amount of reverence and respect" [VIDEO]

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prezjordan · 2021-07 · Reference

I learned best in Scheme because you don't need to parse your input and can just evaluate a tree[0] (Parsing is, in my opinion, the most boring part about writing an interpreter!) Chapter 7 of Crafting Interpreters lays out how an evaluator works in a pretty clean way [1]. I've also blogged about evaluating ASTs in JavaScript [2] Lastly, Gary Bernhardt took it a step further and instead of "evaluating" code, "compiled" it to JavaScript (this tutorial uses Ruby) [3]. Very much a mind-blown moment for me. Have fun!! Writing interpreters remains one of my favorite things to do when learning a new programming language. [0] [VIDEO] [1] [LINK] [2] [LINK] [3] [LINK]

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Sources

Video by MIT OpenCourseWare, played through YouTube.

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