

delay {base}                                 R Documentation

_D_e_l_a_y _E_v_a_l_u_a_t_i_o_n

_D_e_s_c_r_i_p_t_i_o_n_:

     `delay' creates a promise to evaluate the given expres-
     sion in the specifies environment if its value is
     requested.  This provides direct access to lazy evalua-
     tion mechanism used by R for the evaluation of (inter-
     preted) functions.

_U_s_a_g_e_:

     delay(expr, env=.GlobalEnv)

_A_r_g_u_m_e_n_t_s_:

    expr: an expression.

     env: an evaluation environment

_D_e_t_a_i_l_s_:

     This is an experimental feature and its addition is
     purely for evaluation purposes.

_V_a_l_u_e_:

     A promise to evaluate the expression.  The value which
     is returned by `delay' can be assigned without forcing
     its evaluation, but any further accesses will cause
     evaluation.

_E_x_a_m_p_l_e_s_:

     x <- delay({
         for(i in 1:7)
             cat("yippee!\n")
         10
     })

     x^2#- yippee
     x^2#- simple number

