Shenpen

#"Project" name: PyNQ
#IDEA:
#LINQ in C# is cool
#Python doesn't quite need it as it has generatior expressions, sum(), len(), sorted() and itertools.groupby()
#so let's just wrap a nice SQL-like interface over them in order to make them more familiar

#Problem: all these lambdas suck. Any better ways to do it?

#TODOS/QUESTIONS:
#1. is it a good idea?
#2. can it be made to not suck (do something with all those lambdas)?
#3. implement GroupBy()

class From(object):
    def __init__(self, lst):
        self.lst = (x for x in lst)

    def Where(self, func):
        self.lst = ( x for x in self.lst if func(x))
        return self

    def Select(self, func=lambda x: x):
        self.lst = (func(x) for x in self.lst)
        return self

    def Count(self, func=lambda x: x):
        return len([func(x) for x in self.lst])

    def Sum(self,func=lambda x: x):
        return sum(func(x) for x in self.lst)

    def OrderBy(self, func):
        self.lst= sorted(self.lst, lambda x, y: func(x) - func(y))
        return self

    def __iter__(self):
        return self.lst

#examples
table = ((8, 2, 9), (4, 5, 6), (2, 1, 9))
mySum = From(table)\
        .Where(lambda column: column[2]==9)\
        .Sum(lambda column: column[0])

print mySum

myLst = From(table) \
        .Where(lambda column: column[2]==9) \
        .OrderBy(lambda column: column[2])  \
        .Select(lambda column: column[0])

for item in myLst: print item