Function Piping in Python

FunctionPiper.py

# I don't know 100% what this is, but it seems interesting, so I am recording it.

class FunctionPiper:
  def applyAll(self, data):
    if len(self.functionList) > 0:
      for func in self.functionList:
        data = func(data)
    return data

j=FunctionPiper()
j.functionList=[lambda x:x*2,lambda x:x-1]
j.applyAll(5)
# 9


# select the first entry of each list
j.functionList=[lambda x: map(lambda y: y[0], x)]
j.applyAll([[1,2,3],[4,5,6],[7,8,9]])
# [1, 4, 7]


# sum the first entry of each list
j.functionList=[lambda x: map(lambda y: y[0], x), lambda z: reduce(lambda x,y:x+y,z,0)]
j.applyAll([[1,2,3],[4,5,6],[7,8,9]])
# 12

could be just:

class FP2:
... def a(self, data):
... for i in self.functionList:
... data = i(data)
... return data
...
j = FP2()
j.functionList=[lambda x:x*2,lambda x:x-1]
j.a(5)
9

Its a mapping. could be written for a list not just scalar.

You're right. I originally wrote it with the intention of processing lists of lists, but demonstrated it here with just a scalar. I like the way you simplified the iteration over the functions.