Double then increment numbers
Input
compose_map([lambda x: x * 2, lambda x: x + 1], [1, 2, 3])
Output
[3, 5, 7]
Each number is doubled then incremented: 1->2->3, 2->4->5, 3->6->7.
Full lesson preview
Compose multiple functions into a single map pipeline
Create a reusable map pipeline that applies a sequence of functions to each item in an iterable.
Python practice21 minFunctions as Objects (Lambda, Map/Filter)AdvancedLast updated March 20, 2026
Problem statement
You often need to apply several transformations to every element of a sequence. Instead of nesting maps or writing a loop each time, build a reusable pipeline that composes multiple functions and applies them in order to each element.
Write compose_map(funcs, iterable) that:
- Accepts funcs: an iterable (e.g., list or tuple) of callables. Each callable receives the output of the previous one.
- Accepts iterable: any iterable of input values.
- Returns a list where each input element has been transformed by every function in funcs in the same order.
Behavior details:
- If funcs is empty, compose_map should return a list constructed from iterable (no transformation).
- The functions may change types (e.g., int -> str). The pipeline must pass the intermediate result to the next function.
Task
Implement compose_map(funcs, iterable) which chains multiple callables and returns a list of transformed items.
Examples
Input format
Two arguments: (1) funcs: iterable of callables, (2) iterable: any iterable of input items.
Output format
A list containing transformed items (Python list repr).
Constraints
- Do not modify the original iterable in-place. - Always return a list. - Functions are applied in the order provided.
Samples
Sample 1
Input
compose_map([str, lambda s: s + '!'], [1, 2])
Output
['1!', '2!']
Convert numbers to strings then append '!'.