Explanation how to use comptime, the right way

[stefanos82]

The following code works just fine:

require 'C.stdio'

local function foo(f: integer, g: integer, h: integer): void
  local hello <comptime> = "Hello"
  local msg <comptime> = hello .. " world!"
  for color=f,g do
    if color % 16 == 0 then
      C.puts("")
    end
    C.printf("%s\n", msg)
  end
end

foo(0,255,0)

whereas this one does not!

local function color_range(first: integer, last: integer, anyground: integer)
  local resetcolor <comptime> = "\x1b[0m"
  local resetoutput <comptime> = resetcolor .. " "

  for color=first,last do
    if color % 16 == 0 then
      C.puts("")
    end
    C.printf("\x1b[%ld;5;%ldm%3ld%s", anyground, color, color, resetoutput)
  end
end

The error message is

colorsv2.nelua:1:1: from: AST node Block
require 'C.stdio'
^~~~~~~~~~~~~~~~~
colorsv2.nelua:10:3: from: AST node Block
  local resetcolor <comptime> = "\x1b[0m"
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
colorsv2.nelua:11:9: error: compile time variables can only assign to compile time expressions
  local resetoutput <comptime> = resetcolor .. " "
        ^~~~~~~~~~~~~~~~~~~~~~


shell returned 1

@edubart Can you explain to me why the first example works whereas the second does not?