Source code in the icon programming language

# text based adaptaion of 

procedure main(A)

   width := 2 ^ ( 1 + (order := 0 < integer(\A[1]) | 4))  # order of arg[1] or 4
   write("Triangle order= ",order)

   every !(canvas := list(width)) := list(width," ")      # prime the canvas
   every y := 1 to width & x := 1 to width do             # traverse it
      if iand(x - 1, y - 1) = 0 then canvas[x,y] := "*"   # fill

   every x := 1 to width & y := 1 to width do
      writes((y=1,"\n")|"",canvas[x,y]," ")               # print

end