Tutorial: Lines

Lines

sclin's program structure is rather strange. By default, the first line of each program runs; commands exist to allow programs to access and execute other lines.

Some examples - here, the first line runs and ends:

1 1+
2 2+
=> 2

Here, both lines run with the help of ;, which executes the next line:

1 1+ ;
2 2+
=> 2 4

Basing program execution around lines enables some pretty cool abstractions. Program flow can weave between lines like so:

1 1+ ; 3 3+
2 2+
=> 2 4 6

Anonymous recursion is also effortless thanks to @, which executes the current line:

1;
dup 1+ @
=> 1 2 3 4 ...

HINT: Use the -v ("verbose") flag to see this stack grow recursively!

Same with mutual recursion, this time using ;; to execute the previous line:

1 1+ ;
2 2+ ;;
=> 2 4 2 4 ...

I'm still not 100% sure why I kept this artifact of a design decision from lin, but I find it rather ergonomic to work with, and I find it to be a wonderful mechanic that meshes well with the sclin philosophy.