Thats becuse the arduino add the file WProgram.h automatic as the first setp in building. ( Thats where you fin boolean. )
"The Arduino environment performs a few transformations to your main sketch file (the concatenation of all the tabs in the sketch without extensions) before passing it to the avr-gcc compiler.
First, #include "WProgram.h" is added to the top of your sketch. This header file (found in /hardware/cores//) includes all the defintions needed for the standard Arduino core. " from http://arduino.cc/en/Hacking/BuildProcess.
but it does not add this to libraries.