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Compiler for "Easy" language from "Etudes for Programmers" book (1978)

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28 points by begoon 3 months ago · 9 comments

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shrubble 2 months ago

The Etudes book is considered a classic, especially among FSU programmers-the book was licensed for a small amount, translated into Russian and used in many classrooms.

dukoid 2 months ago

I was assuming it's something similar to PL/0 but the grammar looks quite extensive...

  • Joker_vD 2 months ago

    Basically Algol, but with gratuitous "SET" to simplify parsing assignment statements, and without generic "BEGIN" braces: those are baked into "DO"/"THEN"/"ELSE".

    You can probably straightforwardly translate it to Golang by running through a C preprocessor with an obvious set of macros.

ape4 2 months ago

The "FI" for "endif" is like bash.

The semicolons are like C.

The "PROGRAM" section is like COBOL.

  • kragen 2 months ago

    The "fi" thing arose during the Algol-68 process, which Steve Bourne participated in, which is why he put it in his shell. (He would have put "od" there too to terminate "do" if it wasn't already used for a hexdumper.) You also find it in, for example, Dijkstra's Discipline of Programming.

    Semicolons were widely used as statement separators in Algol-family languages, but in Easy they seem to be statement terminators, so they are apparently like C rather than like earlier Algol-family languages such as Pascal.

    Pascal also had the "program" thing. I'm not sure if earlier Algol languages did?

    • IAmBroom 2 months ago

      COBOL precedes Pascal.

      • kragen 2 months ago

        Yes, of course it does. I didn't mean to imply that COBOL got it from Pascal. I meant that the practice was much more widespread than just COBOL, and given that the rest of Easy is clearly an Algol-family language very similar to Pascal or (then-draft) Ada, that's probably where he got it.

  • Rendello 2 months ago

    If you're Stephen R. Bourne, "FI" is also like C!

    (From the Bourne Shell source): https://www.tuhs.org/cgi-bin/utree.pl?file=V7/usr/src/cmd/sh...

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