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That's not really a meaningful criticism. As others have pointed out, the point of Knuth's exercise was not to optimally solve the technical problem, but to dem

That's not really a meaningful criticism. As others have pointed out, the point of Knuth's exercise was not to optimally solve the technical problem, but to demonstrate the effectiveness of Literate Programming (or the lack thereof). The technical problem was just a strawman, so that Knuth had a non-trivial program to demonstrate. With this in mind, McIlroy's pipe example isn't a critique of LP at all -- if anything, it was just a distracting advertisement for the Unix style of composing programs in the shell. What McIlroy could have examined -- and chose not to at the time -- is whether awk, sed, tr, and friends could themselves be written in a literate style, and whether such a rewrite would have achieved the goals that Knuth was setting out for LP. Knuth could have chosen to break his monolith into multiple, loosely-coupled programs, and then written then all in an LP style. But would that have really made the demonstration any more effective?

scythe 7y ago
> Knuth could have chosen to break his monolith into multiple, loosely-coupled programs, and then written then all in an LP style. But would that have really made the demonstration any more effective? I would say yes. Clearly loose-coupling isn't necessary for a program that small. And no, it isn't always optimal. But I have clear memories of being asked to re-do an intro CS assignment three times because it wasn't in a properly object-oriented style. Modularity is not a necessity all of the time, but it is important sometimes. Demonstrating the potential to write reusable code seems just as important as demonstrating anything else. (If the conclusion is "LP helps clarity, but you can't write libraries", is that even positive?) As far as I can tell, "this code has only one useful point of entry" was a key part of the anti-LP argument leveled by McIlroy. After all, isn't the goal to demonstrate that LP works for people who aren't Donald Knuth?
- gmfawcett 7y ago
  I think McIlroy missed the mark here. Single points of entry, and tightly-coupled code, might be reasonable criticisms of Knuth's personal style, but I don't see them as inherent limitations of the LP approach. You could write multiple useful, interesting narratives about a library's core elements -- algorithms, data structures, etc., -- and then write a simple appendix documenting the entry points / API. The style itself doesn't have to get in the way of good program structure. My own critique of LP is really more about the act of writing itself. Many people, programmers included, just aren't skilled at it! Knuth's literate programs are interesting because he's got something interesting to day, and his writing style is engaging. But I wouldn't enjoy having to read (or maintain!) a literate program that was written by a poor writer in a dull, meandering style. Also, Knuth seems to think that the literate style ought to make us into better programmers, simply because we're writing prose along with the code -- that the combination somehow unlocks a better understanding of the problem, how to solve it, and how to explain it to others. That sounds inspiring, but I'm not sure it's really true in the general case. Perhaps more research is needed to find out. :)

scythe 7y ago

> Knuth could have chosen to break his monolith into multiple, loosely-coupled programs, and then written then all in an LP style. But would that have really made the demonstration any more effective? I would say yes. Clearly loose-coupling isn't necessary for a program that small. And no, it isn't always optimal. But I have clear memories of being asked to re-do an intro CS assignment three times because it wasn't in a properly object-oriented style. Modularity is not a necessity all of the time, but it is important sometimes. Demonstrating the potential to write reusable code seems just as important as demonstrating anything else. (If the conclusion is "LP helps clarity, but you can't write libraries", is that even positive?) As far as I can tell, "this code has only one useful point of entry" was a key part of the anti-LP argument leveled by McIlroy. After all, isn't the goal to demonstrate that LP works for people who aren't Donald Knuth?

gmfawcett 7y ago
I think McIlroy missed the mark here. Single points of entry, and tightly-coupled code, might be reasonable criticisms of Knuth's personal style, but I don't see them as inherent limitations of the LP approach. You could write multiple useful, interesting narratives about a library's core elements -- algorithms, data structures, etc., -- and then write a simple appendix documenting the entry points / API. The style itself doesn't have to get in the way of good program structure. My own critique of LP is really more about the act of writing itself. Many people, programmers included, just aren't skilled at it! Knuth's literate programs are interesting because he's got something interesting to day, and his writing style is engaging. But I wouldn't enjoy having to read (or maintain!) a literate program that was written by a poor writer in a dull, meandering style. Also, Knuth seems to think that the literate style ought to make us into better programmers, simply because we're writing prose along with the code -- that the combination somehow unlocks a better understanding of the problem, how to solve it, and how to explain it to others. That sounds inspiring, but I'm not sure it's really true in the general case. Perhaps more research is needed to find out. :)