Implementing the Repository Pattern with LINQ-to-SQL

using System;
using System.Collections.Generic;
using System.Text;


public interface IRepository<T> where T : class
{
    /// <summary>
    /// Return all instances of type T.
    /// </summary>
    /// <returns></returns>
    IEnumerable<T> All();

    /// <summary>
    /// Return all instances of type T that match the expression exp.
    /// </summary>
    /// <param name="exp"></param>
    /// <returns></returns>
    IEnumerable<T> FindAll(Func<T, bool> exp);

    /// <summary>Returns the single entity matching the expression. Throws an exception if there is not exactly one such entity.</summary>
    /// <param name="exp"></param><returns></returns>
    T Single(Func<T, bool> exp);

    /// <summary>Returns the first element satisfying the condition.</summary>
    /// <param name="exp"></param><returns></returns>
    T First(Func<T, bool> exp);

    /// <summary>
    /// Mark an entity to be deleted when the context is saved.
    /// </summary>
    /// <param name="entity"></param>
    void MarkForDeletion(T entity);

    /// <summary>
    /// Create a new instance of type T.
    /// </summary>
    /// <returns></returns>
    T CreateInstance();

    /// <summary>Persist the data context.</summary>
    void SaveAll();
}