returns the type of an expression as string.
Returns the type of the first list element if the expression is an
expression list.
Possible types are:
"ideal"
,
"int"
,
"intmat"
,
"intvec"
,
"list"
,
"map"
,
"matrix"
,
"module"
,
"number"
,
"none"
,
"poly"
,
"proc"
,
"qring"
,
"resolution"
,
"ring"
,
"string"
,
"vector"
.
For internal use only is the type
"?unknown type?"
.