internal static Fallible <TSource> ReduceImpl <TSource>(
this IEnumerable <TSource> source,
Func <TSource, TSource, Fallible <TSource> > accumulator,
Func <Fallible <TSource>, bool> predicate)
{
Debug.Assert(source != null);
Debug.Assert(accumulator != null);
Debug.Assert(predicate != null);
using (var iter = source.GetEnumerator())
{
if (!iter.MoveNext())
{
throw new InvalidOperationException("Source sequence was empty.");
}
Fallible <TSource> retval = Fallible <TSource> .η(iter.Current);
while (predicate(retval) && iter.MoveNext())
{
retval = retval.Bind(val => accumulator(val, iter.Current));
}
return(retval);
}
}
internal static Fallible <TAccumulate> FoldImpl <TSource, TAccumulate>(
this IEnumerable <TSource> source,
TAccumulate seed,
Func <TAccumulate, TSource, Fallible <TAccumulate> > accumulator)
{
Debug.Assert(source != null);
Debug.Assert(accumulator != null);
Fallible <TAccumulate> retval = Fallible <TAccumulate> .η(seed);
using (var iter = source.GetEnumerator())
{
while (iter.MoveNext())
{
retval = retval.Bind(val => accumulator(val, iter.Current));
}
}
return(retval);
}
