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Back to Apple3.14

This is an implementation of Apple3.14 in J, written by User:Conor O'Brien.


I assume the following, since detail is to be desired on the actual spec.

  1. All programs must start with apple3.14 in that case exactly, followed by an optional carriage return (\r) and a necessary newline (\n);
  2. all programs must end with the end command, and that any amount of text may come after it, but will not be executed;
  3. all lines not starting with goto followed by a space are ignored;
  4. any invalid number passed to a goto command causes an error;
  5. negative numbers passed to a goto command print an newline;
  6. and that multiple gotos are allowed.


Without further ado, this is the program, Apple314.ijs:

getpi =: '3'"_`('3.',[:":10#.[:([:-/1 10*[:<.@o.10x^1 0+])"0 i.)@.*
isn   =: [:<./'0123456789'e.~]
throw =: (5)1!:2&5,&LF

3 : 0]1!:1(3)
  NB. split on newlines and remove carriage returns
  lines =. <;._1 LF, y -. CR
  if. -. 'apple3.14' -: > {. lines do. throw 'error: first line is not "apple3.14"' end.
  NB. remove first line
  lines =. }. lines
  for_line. lines do.
    if. 'end' -: >line do. return.
    elseif. 'goto' -: > 0 { wln =. ;: >line do.
      num =. >1 { wln
      if.     isn num                       do. echo getpi ". num
      elseif. ('-' -: {. num) *. isn }. num do. echo ''
      elseif. 1                             do. throw 'error: malformed number "' , num , '"'
exit 0

Running the program

You can execute programs like this:

On windows:

type <filename> | Apple314.ijs

On bash/related:

cat <filename> | Apple314.ijs

Further notes

This program currently does not display the entirety of sufficiently long strings. However, this is currently being worked on.