Neat way to write loop that has special logic for the first item in a collection

Question

Often I have to code a loop that needs a special case for the first item, the code never seems as clear as it should ideally be.

Short of a redesign of the C# language,

Answer 1

You could try:

collection.first(x=>
{
    //...
}).rest(x=>
{
    //...
}).run();

first / rest would look like:

FirstPart first(this IEnumerable c, Action a)
{
    return new FirstPart(c, a);
}

FirstRest rest(this FirstPart fp, Action a)
{
    return new FirstRest(fp.Collection, fp.Action, a);
}

You would need to define classed FirstPart and FirstRest. FirstRest would need a run method like so (Collection, FirstAction, and RestAction are properties):

void run()
{
    bool first = true;
    foreach (var x in Collection)
    {
        if (first) {
            FirstAction(x);
            first = false;
        }
        else {
             RestAction(x);
        }
    }
}