Thanks to wrapping work of Jennifer Balakrishnan of M.I.T., we can compute explicitly with the L-series of the modular form \Delta. Like for elliptic curves, behind these scenes this uses Dokchitsers L-functions calculation Pari program.
sage: L = delta_lseries(); L L-series associated to the modular form Delta sage: L(1) 0.0374412812685155
In some cases we can also compute with L-series attached to a cusp form.
sage: f = CuspForms(2,8).newforms()[0] sage: L = f.lseries() sage: L(1) 0.0884317737041015 sage: L(0.5) 0.0296568512531983
Unfortunately, computing with the L-series of a general newform is not yet implemented.
sage: S = CuspForms(23,2); S Cuspidal subspace of dimension 2 of Modular Forms space of dimension 3 for Congruence Subgroup Gamma0(23) of weight 2 over Rational Field sage: f = S.newforms('a')[0]; f q + a0*q^2 + (-2*a0 - 1)*q^3 + (-a0 - 1)*q^4 + 2*a0*q^5 + O(q^6)
Computing with L(f,s) totally not implemented yet, though should be easy via Dokchitser.