@scan(f:function, t:tab)
returns the tab of the partial reduction by f of the elements of t: 
       [ t[0], f(t[0],t[1]), f(f(t[0], t[1]),t[2]), ...]
For example, the tab of the partial sums of the integers between 0 (included) and 10 (excluded) is computed by the expression: 
       @scan(@+, [$x | $x in (10)])  -> [0,1,3,6,10,15,21,28,36,45]

If t is empty, the results in undef.

See also @reduce and @map.

See also Tab Manipulations @car,    @cdr,    @clear,    @concat,    @cons,    @copy,    @count,    @dim,    @domain,    @drop,    @empty,    @find,    @flatten,    @gnuplot,    @insert,    @iota,    @is_list,    @is_prefix,    @is_subsequence,    @is_suffix,    @lace,    @last,    @listify,    @map,    @max_val,    @median,    @member,    @normalize,    @occurs,    @parse,    @permute,    @push_back,    @push_front,    @range,    @reduce,    @remove,    @remove_duplicate,    @replace,    @reshape,    @resize,    @reverse,    @rotate,    @scan,    @scramble,    @size,    @slice,    @sort,    @sputter,    @stutter,    @succession,    @tab_history,    @tab_history_date,    @tab_history_rdate,    @take    @to_num