Is this a good use for lambda

[Charlie Taylor]

I find that I use lambda functions mainly for callbacks to things like
integration or root finding routines as follows.

flow = integrate(lambda x: 2.0*pi * d(x)* v(x) * sin(a(x)),xBeg, xEnd) 

root = findRoot(xBeg, xEnd, 
       lambda x: y2+ lp*(x-x2) -wallFunc( x )[0], tolerance=1.0E-15)

I have tried using named functions instead of using lambda functions,
however, I always end up with a convoluted, hard to follow mess.

Is there a better solution than a lambda in the above situations?