public static <R> IntFunction<R> intFunction(CheckedIntFunction<R> function, Consumer<Throwable> handler) {
        return t -> {
            try {
                return function.apply(t);
            }
            catch (Throwable e) {
                handler.accept(e);

                throw new IllegalStateException("Exception handler must throw a RuntimeException", e);
            }
        };
    }
Wrap a {@link CheckedIntFunction} in a {@link IntFunction} with a custom handler for checked exceptions.
<p>
Example:
<pre><code>
IntStream.of(1, 2, 3).mapToObj(Unchecked.intFunction(
    i -> {
        if (i &lt; 0)
            throw new Exception("Only positive numbers allowed");

        return "" + i;
    },
    e -> {
        throw new IllegalStateException(e);
    }
));
</code></pre>
jOOL/src/main/java/org/jooq/lambda/Unchecked.java