Integral involving Bessel function - sympy

Question

Is there any way to get sympy to perform this integral?
x=var('x')
L=var('L')
Q.positive(1/L)
integrate(besseli(1,x) * exp(-x**2/(4*L)-L),(x,0,inf))
Sympy just returns the integral:
Integral(exp(-L - x**2/(4*L))*besseli(1, x), (x, 0, +inf))
Mathematica does it:
Integrate[BesselI[1, x] Exp[-(x^2/(4 L)) - L], {x, 0, Infinity}]
Result:
ConditionalExpression[1 - E^-L, Re[1/L] > 0]
EDIT: using the answer provided below, a better way to perform this integral is:
L=var('L',real=True,positive=True)
x=var('x',real=True,positive=True)
integrate(besseli(1,x) * exp(-x**2/(4*L)-L),(x,0,oo))

Answer 1

The problem is that you are using inf, which I guess is Float('inf'). You want oo, the symbolic infinity. SymPy should probably be smarter about converting Float('inf') to oo.
In [1]: x=var('x')
In [2]: L=var('L')
In [3]: Q.positive(1/L)
Out[3]: Q.positive(1/L)
In [5]: integrate(besseli(1,x) * exp(-x**2/(4*L)-L),(x,0,oo))
Out[5]:
⎧ ⎛ L ⎞ -L │ ⎛ 1 ⎞│ π
⎪ ⎝ℯ - 1⎠⋅ℯ for │periodic_argument⎜─────────────, ∞⎟│ < ─
⎪ │ ⎝polar_lift(L) ⎠│ 2
⎪
⎪∞
⎪⌠
⎨⎮ 2
⎪⎮ x
⎪⎮ -L - ───
⎪⎮ 4⋅L
⎪⎮ ℯ ⋅besseli(1, x) dx otherwise
⎪⌡
⎩0

Answer 2

The original expression now works in SymPy because inf is automatically recast to oo:
>>> inf=float('inf')
>>> x=var('x')
>>> L=var('L')
>>> Q.positive(1/L)
Q.positive(1/L)
>>> integrate(besseli(1,x) * exp(-x**2/(4*L)-L),(x,0,inf))
Piecewise(
((exp(L) - 1)*exp(-L), Abs(arg(L)) < pi/2),
(Integral(exp(-L - x**2/(4*L))*besseli(1, x), (x, 0, oo)), True))