I wouldn't want to write the parser

As in Algol, the programs are pretty-printed in different fonts, as in ABC 80 BASIC, the pretty-printing is enforced, as in COBOL, the programs pretend to be in English, as in Fortran, you have to use continuation characters, as in C++, the error messages are incomprehensible: AppleScript.

Here is our old friend, the Hailstone program:

on run
    display dialog "Seed" default answer "" buttons {"OK"} default button "OK"
    set a to (text returned of result) as integer
    set outstring to a as string
    repeat until a is equal to 1
        if a mod 2 is equal to 0 then
            set a to a div 2
        else
            set a to a * 3 + 1
        end if
        set outstring to outstring & ", " & a as string
    end repeat
    display dialog outstring buttons {"OK"} default button "OK"
end run