Your solution is not a good one, because if a general array is passed to copy-to it will cause an error if all the elements are not the same type as the first one. For example, (copy-to #(1.0d0 1)) will behave incorrectly. By the way, your example with #(1d0 2d0) fails on SBCL as well, and should fail everywhere because #( ) is making a general (T) array. It is unfortunate that CLISP apparently does not have specialized arrays, but the proper solution is to use a different function. The correct solution when copying from a general array is to explicitly specify the element-type. This capability is provided by the function #'copy (copy #(1d0 2d0) :grid-type 'grid:foreign-array :element-type 'double-float) The function #'copy-to is provided merely as a convenient shortcut to using #'copy which works in many situations. The solution to your problem is to use copy with explicit element-type instead of copy-to. After debating whether to eliminate copy-to, I have added another optional argument, element-type, that defaults to *default-element-type*, and this should fix your problem. However, it is meant only as a convenience for interactive code, it should really not be put into files relying on the default value specials which may be changed. So I have also removed its use in GSLL itself. This change is untested and made in 86671c4ef057, which is in the multiple-systems branch and will be merged into master soon. I have added antik-devel to this email because this an Antik issue and has nothing to do with GSLL. On Fri, Jan 4, 2013 at 10:39 AM, Mirko Vukovic <mirko.vukovic@gmail.com>wrote:

The following works in sbcl+grid:

(copy-to (make-array 2 :element-type 'double-float :initial-contents '(1.0d0 2.0d0)) 'grid:foreign-array)

But it does not work in clisp+grid.

The root cause lies in the function grid/array.lisp/element-type. It uses `(array-element-type grid)'.

But this can present a problem. Quoting hyperspec:

(Because of *array* <http://26_glo_a.htm#array> *upgrading*, this *type specifier* <http://26_glo_t.htm#type_specifier> can in some cases denote a *supertype* <http://26_glo_s.htm#supertype> of the *expressed array element type* <http://26_glo_e.htm#expressed_array_element_type> of the *array*.)

In CLISP, array-element-type returns `T' when passed #(1d0 2d0)

It returns T even when passed a simple array:

(array-element-type (make-array 2 :element-type 'double-float :initial-contents '(1.0d0 2.0d0) :adjustable nil :fill-pointer nil :displaced-to nil) )

The proposed fix is

(defmethod element-type ((grid array)) (type-of (row-major-aref grid 0)) #+skip(array-element-type grid))

Now copy-to works in clisp as well.

Mirko

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