Readit NewsWith traditional Q/A-style spaced repetition, I feel like accumulating a long list of isolated facts sometimes (I know, you can remedy this a bit by also quizzing connections, context, but I feel like the general tendency still remains).
Local variables are also not necessary to have reasonable ergonomics, even in mathy contexts. Instead, the language can define special operators that access fields on the stack by type name and move or copy them to the top of the stack. For some reason, in the math example, the author deliberately added an unnecessary parameter that had to be dropped and put the arguments in the wrong order. Cleaning up the signature, there are several reasonable ways to solve the problem in a concatenative language with the features I've described.
type n number
type y n
type x n
def op_math_example [(y x) -> (n)] \\x * \\y \\y * + \y abs -
Even if we restore the original signature and use the author's syntax, there is a much cleaner solution to the problem without the move/copy operators.
def sq dup *
def op_math_full drop swap sq over sq + swap abs -
type n number
type x n
type y n
type z n
def sq [(n) -> (n)] dup *
def op_math_impl [(y x) (n)] sq over sq + swap abs -
def op_math_full [(x y z) -> (n)] drop swap op_math_impl
def projection_size [(x y z) -> (n)] drop swap PRINT_STACK sq over sq + swap abs -
1 2 3 projection_size
({ y 2 } { x 1 })
I have only used concatenative languages that I have implemented myself, however. I have read quite a bit about forth, but for me, there are clear problems with vanilla forth that are solved for me with the meta operators like [, [[, \ and \\ as well as good debug tools like PRINT_STACK above. Forth was an incredible discovery for its time. We can do a lot better now.
There is also one that is called "tody" that we didn't try out. Both require a small subscription fee though, which I really dislike. I wish I had found a nice open source alternative. Besides the subscription fee (which was like 18€/year for us both), I have no complaints yet about the app.