Type-safe `read` in Haskell

Question

Learn You a Haskell discusses the following data type:

data Day = Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday   
           deriving (Eq, Ord, Show, Read, Bounded, Enum)  

The book demonstrates how to use read to parse a String into a Day type.

$ read "Saturday" :: Day
Saturday

However, I can pass in a non-Day value, resulting in an exception.

$ read "foo" :: Day
*** Exception: Prelude.read: no parse

What's a type-safe way to use read in the above example?

Answer 1

In addition to the old standard function reads mentioned by @JonPurdy, there's also the more recently added

Text.Read.readMaybe :: Read a => String -> Maybe a

which is simpler to use when the string contains just one value to parse.