Comment by mlajtos | Hacker News Reader

Comment by mlajtos | Hacker News Reader

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+ was invented by Nicole Oresme in 1360. He was tired of writing “et” (latin for and) over and over.

While we have some standardized operators that got into programming languages, we are doing a very poor job of using symbols even for very useful functions. Iverson was, and still is, right about terse notation. However, APL/J/BQN are not flexible enough in this regard. You can’t introduce new symbols. For example, you CAN do “et = +”, but you CAN’T do “• = *”. User-level definition of custom operators would enable APL-family to break out of the diamond world in which they live in.

I don't think user-level definitions of custom symbols are that useful, but for what it's worth, you can do it in ngn/k...

    (Π):!/:  / make table
    
    Π[`a   `b
     ( 1    2
       3    4)]

TIL that ngn/apl and ngn/k supports user-defined symbols. Thank you!

Creating custom notation (aka DSL) can be very liberating. As Iverson noted, having a good notation enables you to think previously unthinkable thoughts. Einstein’s theory of relativity was enabled by use of his sum notation. [0]

Of course, it should be paired with the right user interface. Inputting non-ASCII chars on keyboards is still pretty cumbersome. But APL with its weird symbols is perfect for paper and pencil, where it has its origins. [1]

Some might see pencil-and-paper interface for an array-oriented REPL as going backwards, but I consider pencil to be mightier than the keyboard. Finally you could sketch visually your algorithm beside the runnable code.

[0]: https://en.m.wikipedia.org/wiki/Einstein_notation [1]: https://mlajtos.mu/posts/new-kind-of-paper

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