FIRST_CONVConv.FIRST_CONV : conv list -> convApply the first of the conversions in a given list that succeeds.
FIRST_CONV [c1,...,cn] t returns the result of applying
to the term t the first conversion ci that
succeeds (or raises UNCHANGED) when applied to
t. The conversions are tried in the order in which they are
given in the list.
FIRST_CONV [c1,...,cn] t fails if all the conversions
c1, …, cn fail when applied to the term
t. FIRST_CONV cs t also fails if
cs is the empty list.