fundamentals-fp-lab5.md

Lab5

Learning objective: To control program flow using iterative functions.

Prerequisite

1. Daml SDK installed and setup
2. Daml Fundamentals Training: Functional Programming in Daml - Lessons 1 to 10 completed.

Problem statement 1

There is a list of tuples provided to you as shown below:

song = [("do", "a deer, a female deer"), ("re", "a drop of golden sun"), ("mi", "a name, I call myself"), ("fa", "a long long way to run")]

Each tuple has a note, e.g. 'do', and a meaning, 'a deer, a female deer'.

Given this data, write a script to extract the notes and meanings into two separate lists and print them first in the given order.

A sample output is as shown below:

Trace: 
  ["do","re","mi","fa"]
  ["a deer, a female deer","a drop of golden sun","a name, I call myself","a long long way to run"]

Hint:

• You may find map function useful

Problem statement 2

This problem has two parts

1. Using the map function, write a function named multiTermFrequency that takes a Text, say x, and a list of Texts, say y, as input. It then returns a list of numbers with each number at index i representing the frequency of x in the i-th element in y.

   Here is a script to test your function:

   testMultiTermFrequency = script do 
       let x = "hello"
       let y = [ "hello from the other side I must have called a thousand times", 
               "You say goodbye and I say hello hello hello",
               "hello is it me you’re looking for",
               "hello hello is anyone home"
               ]
   
       debug $ multiTermFrequency x y
       return()
   

   It should produce the following output:

   Trace: 
   [0.0833333333,0.3333333333,0.1428571429,0.4]
   

2. Write the same function as above using foldr instead of map function

Hint:

• If you did Lab2 where you wrote a function named termFrequency, then you should be able to reuse it here.