RCR 299: Indented code blocks

   if ... then
                if ... then
                        ...
                end            |
        end                    |  <--- 3 lines to indicate end of code block

        if 5 > 4:
                if 5 > 2:                          <--- indentation is compulsory
                       puts "hello"

The other syntax is still compatible: def f()

        if 5 > 4
                if 5 > 2
                        puts "hello"               <--- indentation is optional
                end
        end

In the future the "end of block" syntax may get deprecated and replaced by indented blocks.

Languages like Python and Haskell (see the 'do' syntax) use indented blocks to avoid this. For the above example: if ... :

   if .... :
                if ... :
                        ...

In this example ':' means "beginning of indented block" We don't have to write the three ends as they are put automatically by the lexer. As a restriction, each of the inner blocks have to be indented. The same may be applied to any definition (class, modules, methods): class c:

   ...
        ...

Most of the current programs may remain untouched since it is not common to use ':'. Compatibility is assured.

In the future the "end of block" syntax may get deprecated and replaced by indented blocks and we may be able to write: if 5 > 4 <-- the ':' is no more required

   puts "hello"