php7 shimmying类型关键字，以方便过渡

I want to improve my php5 codebase and make it ready for php7. alas, for code that I want to run on a php5 interpreter, I would like to do the C preprocessor equivalent of

 #define int
 #define float
 #define string
 #define bool

and perhaps

 #define array

so that

 function(int $x) {...}

is seen by php5 to be the same as

 function($x) {...}

it would also clarify the meaning of my code to me, even if it does not trigger anything in the interpreter itself.

is this possible?