Dear Catherine Greenhill,

Does anyone know what GAP does first when it reads the "*" symbol,
ie checking which domain the elements belong to, whether they
are records with an operations record containing a * function, etc.
I assume GAP does things like this but if anyone knows which order it
does them in, it would be very helpful.

---------------------------cut here -----------------------------------------
/****************************************************************************
**
*V  HdCallProd  . . . . . . . . . . .  handle of the 'prod' function call bag
**
**  'ProdRec' returns the product of the two operands  <hdL>  and  <hdR>,  of
**  which at least one must be a record.
**
**  '<left> * <right>'
**
**  The product of two records or an  object  and  a  record  is  defined  as
**  follows:
**
**  If the right operand <right> is a record
**    and is has a element with the name 'operations', which is a record,
**    and this record has a element '*', which is a function,
**  or if the left operand <left> is a record
**    and is has a element with the name 'operations', which is a record,
**    and this record has a element '*' which is a function,
**  then this function is called with <left> and <right> as arguments
**    and '<left> * <right>' is the value returned by this function.
*/
---------------------------cut here -----------------------------------------

Example:

gap> r := rec( operations := rec( \* := function(x,y) Print("r\n"); end ) );;
gap> l := rec( operations := rec( \* := function(x,y) Print("l\n"); end ) );;
gap> 1 * r;
r
gap> r * 1;
r
gap> l * r;
r
gap> l * 1;
l

best wishes
Frank