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Type Synonyms

Use keyword "type", not "data"

  • Type synonyms don't actually make anything new, just making a synonym for an already existing type.
  • Just use synonyms to convey more information to make our code more descriptive.

Synonyms for simple types​

> type Name = String
> :paste
… myName1 :: Name
… myName1 = "Joe"
…
> myName1
"Joe"

Synonyms for complex types​

Synonyms for complex types, such as Record,

type Person = { name :: String, age :: Int, address :: String }

p1 :: Person
p1 = {name: "Joe", address: "Fake city", age: 43}

when use 'data', when use 'type'?