Lambdas

Lambda Expressions

Lambdas (anonymous functions) use backslash notation — the \ resembles the Greek letter λ:

\x -> x + 1          -- adds 1
\x y -> x * y        -- multiplies two numbers

With Higher-Order Functions

Lambdas are most useful when passed to map, filter, foldl, etc.:

map (\x -> x * x) [1..5]
-- [1,4,9,16,25]

filter (\x -> x > 3) [1..6]
-- [4,5,6]

Partial Application

Often, a lambda can be replaced with partial application:

map (\x -> x + 10) [1,2,3]
-- same as:
map (+10) [1,2,3]
-- [11,12,13]

Your Task

Use map with a lambda to convert a list of temperatures in Celsius to Fahrenheit. Formula: f = c * 9 / 5 + 32. Print the result for [0, 20, 37, 100].