[Rochus]

> The question I have is why following established principles should matter

Apparently I still don't understand your question, sorry. For what I understand, following established principles is part of the engineering profession; it has proven to be the right thing to do over decades, and it is part of engineering education.

> I would have expected that the ergonomics of a language and measurement of the "level of suffering" would be with respect to the programmer, not the one experiencing the use of the software that's developed as a result.

Usually not the "level of suffering" is measured in human factors engineering, but the time needed and degree of fulfillment of typical tasks a typical representative of a test group is suppost to perform. You can do that with different designs and can then conclude which one meets the performance requirements best. Human factors typically enter a specification as performance requirements (what functions shall the system implement and how well). Given a programming language, you could measure how long a typical programmer requires to complete a specific task and how many errors the implementation has in the first version.

[saghm]

> Apparently I still don't understand your question, sorry. For what I understand, following established principles is part of the engineering profession; it has proven to be the right thing to do over decades, and it is part of engineering education.

I agree that following established principles is important, but my understanding is that the principles get established because they're better at leading to desirable outcomes. I'm trying to understand what the outcomes are that the principles you describe are intended to lead to. From your most recent two replies, my best interpretation is that it leads to fewer errors overall in the programs produced, but that wasn't as apparent to me from your first comment. I do think I understand now though.

[Rochus]

> I'm trying to understand what the outcomes are that the principles you describe are intended to lead to.

The application of the principles of Human factors engineering to the design of systems reduces human errors, increases productivity, and enhances safety, health and comfort when interacting with these systems. For a programming language, taking human factors into account appropriately means that the target group of language users (i.e. programmers) is sufficiently capable of performing their tasks in all phases of a program's life cycle, e.g., they are not cognitively overwhelmed, and the likelihood of misunderstandings or mistakes is reduced. However, they should neither be unnecessarily restricted or hindered in their work, because also this creates unnecessary extraneous cognitive load that exhausts the programmer's limited working memory capacity. Human working memory can hold only 3-5 "chunks" of information simultaneously. This is a well-documented, hard biological constraint; when programming languages impose excessive formalism, they force programmers to juggle more mental "chunks" than working memory can handle. Self-explanatory code (which includes avoiding incomprehensible abbreviations or confusing syntax) reduces the cognitive load on the programmer. Ada's explicit human factors principle states: "Code is read more than written"; over a program's lifetime, especially in large, long-lived systems, code is read orders of magnitude more often than it's written; Ada's formalism optimizes for the more frequent activity (reading and maintenance) at the expense of the less frequent activity (initial writing). As a language designer, you therefore have to find the right balance, which of course is a function of your target audience, and the primary activities they will perform with the language.