Matrix in ATS

matrix.dats

#include "share/atspre_staload.hats"
    
typedef matrix (a:t@ype) = mtrxszref (a)

extern fun {a:t@ype} matrix_transpose (matrix (a)): matrix (a)
extern fun {a:t@ype} foreach (matrix (a), (a, size_t, size_t) -<cloref1> void): matrix (a)
extern fun matrix_print (matrix (int)): void

implement {a} foreach (m, f) = let
    val nrow = mtrxszref_get_nrow (m)
    val ncol = mtrxszref_get_ncol (m)

    fun do_row (row: size_t):<cloref1> void = 
        if row >= nrow then () 
        else let 
            val _ = do_col (row, size_of_int (0))
        in 
            do_row (row + size_of_int (1))
        end
    and do_col (row: size_t, col: size_t):<cloref1> void = 
        if col >= ncol then ()
        else let
            val _ = f (m[row, col], row, col)
        in
            do_col (row, col + size_of_int (1))
        end

    val _ = do_row (size_of_int (0))
in 
    m
end

implement matrix_print (m) = () where {
    val ncol = mtrxszref_get_ncol (m)
    val _ = foreach<int> (m, lam (e, r, c) =<cloref1> () where {	
                    val _ = fprint (stdout_ref, e)
                    val _ = if c = ncol - size_of_int (1) then println! ()
                })
}

implement {a} matrix_transpose (m) = let 
    val nrow = mtrxszref_get_nrow (m)
    val ncol = mtrxszref_get_ncol (m)
    val n = mtrxszref_make_elt (ncol, nrow, m[0,0])
    val _ = foreach (m, lam (e, r, c) =<cloref1> () where {val _ = n[c, r] := e})
in 
    n
end

implement main0 () = () where {
    val m = mtrxszref_make_elt<int> (size_of_int (5), size_of_int (8), 0)
    val _ = matrix_print (matrix_transpose (m))
}