How can I define cas function of an operator(mathematical term)?

[Albert Chan]

Code:

NORM1(f,a,b) :=
BEGIN
LOCAL c := int(f(¬x)*conj(f(¬x)), ¬x, a, b);
unapply( f(¬x)/sqrt(c), ¬x);
END;

Cas> NORM1(t -> sin(2*pi*t), 0, 1)

(¬x) -> sin(2*π*¬x)/√2*2

Cas> NORM1((x)->x*(LL-x),0,LL)

(¬x) -> ¬x*(LL-¬x)/√(LL^5/30)

Examples taken from video, How to Normalize a Wave function in Quantum Mechanics

Update:
CyperAngel had suggested "¬x", to reduce chances of name conflict.
If variables used always start with alphabet, we are safe.