>So your argument is that ls is not efficient enough in its implementation
My complaint wasn't about the efficiency of ls, it was the fact that valuable information that is required for correctness is thrown away to achieve compatibility with the unix 'stream of text' interface and the attempt to recover that information leads to incorrect results. The paradigm is just fundamentally broken.
>you would suggest replacing all of that with an object model that implements the equivalent of Ruby's enumerable. Got it.
I don't even like Ruby at all (ironically, I find its grammar far too complex and shell-like to be able to parse in my head), so I've no idea what you are talking about. You seem to be assuming that everybody who dislikes the shell must be some strawman hipster.
>there are exceptions -- e.g., files with newlines in their name
I honestly find it extremely bewildering that any programmer would see that as being acceptable. It's not just that it fails to give the correct result, it fails silently. Silent data corruption is surely just about the worse class of bug.
>But pedagogically, I can assure you that teaching people shell is easier than teaching them map-reduce.
I presume you mean the functional ideas of map, reduce, and filter, not MapReduce ( https://en.wikipedia.org/wiki/Map-reduce ). The latter is irrelevant to the discussion.
My experience is the exact opposite. I found understanding the concepts of map and filter trivial. If you can understand a loop you can understand them. Reduce/fold isn't hard to understand either, although a bit tricker to make use of. Your example didn't use reduce anyway. Map and filter are typically much easier to use and reason about than a for loop in C, or a chain of commands in a shell script.
The shell is an absolute nightmare to learn. I have tried to learn to use it numerous times of the last decade or so, and I have always forgotten it the next time I come to do anything in the shell. The amount of knowledge you need to actually do anything is huge (the awk language, obscure and terse command names, complex regexes, memorising a bunch of command flags, memorising the output format of commands - usually a format designed for displaying to users rather than machine parsing, the shells ridiculously complex grammar, how to escape things etc etc) Your example illustrates that. It would have taken me 20 mins at least to put together that line of code you gave. Also, it's not like you escape having to understand concepts like map and filter. If you don't understand them (not necessarily by name) then you won't be able to write the line of unix commands you gave.
>Shell is easy to learn because people innately understand "and then do this with it".
People might find the concept of piping data easy to understand (I'm not convinced they do to be honest), but that alone won't do them much good because as your examples showed, you always need to run a bunch of complex and obscurely named commands, regex, or awk on the data to make the next command able to understand it.