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12.0 Fundamentals of functional programming
12.2 Programming with functions
12.2.1 Function composition
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What is function composition in functional programming?
Chaining functions together
Functions in function composition are treated as
first-class citizens
.
Function composition is typically done from right to
left
What is the common mathematical notation for function composition?
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
If
g
(
x
)
=
g(x) =
g
(
x
)
=
x
+
x +
x
+
2
2
2
and
f
(
y
)
=
f(y) =
f
(
y
)
=
y
∗
y *
y
∗
3
3
3
, then f(g(x)) = 3x + 6
Steps in evaluating the function composition
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
1️⃣ Compute
g
(
x
)
g(x)
g
(
x
)
2️⃣ Pass the result to
f
f
f
3️⃣ Compute
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
Function composition
enhances code readability and maintainability.
Match the feature with its corresponding paradigm:
Structure ↔️ Modular and chained
Reusability ↔️ Excellent
Maintenance ↔️ Simple updates
Function composition breaks down complex tasks into smaller, reusable
functions
What is function composition in functional programming?
Applying one function to another
In function composition, functions are treated as
first-class citizens
.
In mathematical notation, function composition is represented as
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
In function composition, functions are applied from left to right.
False
Match the feature with its corresponding approach:
Notation ↔️
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
Clarity ↔️ Highly structured
Execution ↔️ Right to left
What is one benefit of using function composition in programming?
Modularity
Function composition enhances code clarity by chaining
functions
together.
Function composition provides excellent
reusability
Order the steps involved in applying function composition in Python.
1️⃣ Functions are first-class citizens
2️⃣ Application occurs from right to left
3️⃣ Notation follows
f
(
g
(
x
)
)
f(g(x))
f
(
g
(
x
))
In Python, functions used in
composition
must be defined before being composed.
How is a composed function created in Python using
λ
\lambda
λ
?
lambda x: f(g(x))
Function composition in
Python
applies functions from right to left.
Function composition is used to uppercase the first letter of a string and reverse it, with the notation
f
(
g
(
t
e
x
t
)
)
f(g(text))
f
(
g
(
t
e
x
t
))
Function composition can combine uppercase_first and reverse_string to format text in
Python
.