CSc 120: Format (Recursive)

Expected Behavior

Write a recursive function fmt(spec, values) that is a very simple variant of Python's str.format method. Here's an example of usage:

>>> fmt("x = {}, y = {}", [10, 20])
'x = 10, y = 20'

fmt(spec, values) returns a copy of the string spec where the Nth occurrence of "{}" is replaced by the Nth value in values.

Assume that there are a sufficient number of values to fill all occurrences of "{}". If there are excess values, they are simply ignored.

Programming Requirements

IMPORTANT: You may not use str.format.

Programming Requirements

• if statements;
• return statements;
• assignment;
• recursive function calls (if you use a helper function, then it must be recursive);
• comparison operations (==, !=, etc.);
• list indexing and slicing;
• list and string concatenation.

Solutions that go outside these constructs, e.g., by using for/while loops or list comprehensions, will not get credit.

Examples

1. fmt("testing",[1,2,3])
   return value: 'testing'

2. fmt("{{},{},{}}",[1,'two',3])
   return value: '{1,two,3}'

3. fmt("L = {}.",["just a test".split()])
   return value: "L = ['just', 'a', 'test']."

4. fmt("x = {}, y = {}", [10, 20])
   return value: 'x = 10, y = 20'