does lack of type declarations make Python unsafe?

Mirko Zeibig mirko-lists at
Wed Jun 18 11:45:49 CEST 2003

beliavsky at wrote:
> The beginning of the following Fortran 95 subroutine, for example,
> provides useful information both to the compiler and to a programmer
> trying to understand what it does:
> subroutine solve_lsq_svd_rmse(aa,bb,xx,rmse,ierr)
> ! solve a set of least-squares linear equations and compute the rmse
> real     , intent(in)   :: aa(:,:) ! matrix of independent variables
> real     , intent(in)   :: bb(:)   ! vector of dependent variable
> real     , intent(out)  :: xx(:)   ! solution of least-squares problem
> real     , intent(out)  :: rmse    ! rmse of regression
> integer  , intent(out)  :: ierr    ! error flag
> In Python, to ensure that aa is a 2-D array and that bb and xx are 1-D
> arrays, you need to write some checking code, which will not be as
> clear as the above declarations IMO. Even if you do this, the errors
> will be caught at run time, not compile time.

What about using the array-module for this?

from import array
aa = [array('d', aa[0]), array('d', aa[1])] # matrix of independent variables
bb = array('d', bb)                         # vector of dependent variable
xx = array('d')                             # solution of least-squares problem


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