\DOC delta_map

\TYPE {delta_map : ('a -> 'a delta) -> 'a list -> 'a list delta}

\SYNOPSIS
Apply a function to a list, sharing as much structure as possible.

\KEYWORDS
sharing.

\DESCRIBE
An application {delta_map f list} applies {f} to each member {[x1,...,xn]}
of {list}. If all applications of {f} return {SAME}, then {delta_map f list}
returns {SAME}. Otherwise, {DIFF [y1,...,yn]} is returned. If {f xi}
yielded {SAME}, then {yi} is {xi}. Otherwise, {f xi} equals {DIFF yi}.

\FAILURE
If some application of {f xi} raises {e}, then {delta_map f list} raises {e}.

\EXAMPLE
See the example in the documentation for {delta_apply}.

\SEEALSO
Lib.delta, Lib.delta_apply, Lib.delta_pair.
\ENDDOC