GIML: Tutorial 1: duplicate
duplicate: the answer
<![CDATA[fun duplicate s = s ^ s;
duplicate "go";
]]>
The label s is the formal parameter - given in the definition of
duplicate. The value "go" is the actual parameter - given in an
execution of duplicate.
A common mistake is to put the formal parameter in quotes, perhaps in order to
convince the interpreter that it really is a string. For example:
<![CDATA[
fun duplicate "s" = "s"^"s";
]]>
ML will accept this, however defines a function which is defined at exactly
one value only. You can evaluate the expression duplicate "s"; only
any other parameter value will fail. The expression duplicate "x";
for example will not evaluate, you will an error message such "uncaught
Match exception".