fakedata-0.8.0: README.md
[](https://hackage.haskell.org/package/fakedata)
[](http://stackage.org/nightly/package/fakedata)
[](http://stackage.org/lts/package/fakedata)
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**Table of Contents**
- [fakedata](#fakedata)
- [Tutorial](#tutorial)
- [Generating address](#generating-address)
- [Generating name](#generating-name)
- [Generate quotes from the movie Back to the Future](#generate-quotes-from-the-movie-back-to-the-future)
- [Combining Fake datas](#combining-fake-datas)
- [Combinators](#combinators)
- [listOf](#listof)
- [oneOf](#oneof)
- [suchThat](#suchthat)
- [Comparision with other libraries](#comparision-with-other-libraries)
- [Acknowledgments](#acknowledgments)
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fakedata
========
This library is a port of Ruby's
[faker](https://github.com/stympy/faker). It's a library for producing
fake data such as names, addressess and phone numbers. Note that it
directly uses the source data from that library, so the quality of
fake data is quite high!
Tutorial
--------
### Generating address
``` {.shellsession}
~/g/fakedata (master) $ stack ghci
λ> import Faker.Address
λ> address <- generate fullAddress
λ> address
"Apt. 298 340 Ike Mission, Goldnertown, FL 19488-9259"
```
### Generating name
``` {.shellsession}
λ> fullName <- generate name
λ> fullName
"Sherryl Steuber"
```
### Generate quotes from the movie Back to the Future
λ> import Faker.Movie.BackToTheFuture
λ> import Faker.Combinators
λ> qs <- generateNonDeterministic $ listOf 5 quotes
λ> qs
[ "Yes. Yes. I'm George. George McFly. I'm your density. I mean, your destiny."
, "Hello? Hello? Anybody home? Huh? Think, McFly. Think! I gotta have time to get them retyped. Do you realize what would happen if I hand in my reports in your handwriting? I'll get fired. You wouldn't want that to happen, would ya? Would ya?"
, "Lorraine. My density has brought me to you."
, "See you in about 30 years."
, "You really think I ought to swear?"
]
### Combining Fake datas
``` {.haskell}
{-#LANGUAGE RecordWildCards#-}
import Faker
import Faker.Name
import Faker.Address
import Data.Text
data Person = Person {
personName :: Text,
personAddress :: Text
} deriving (Show, Eq)
fakePerson :: Fake Person
fakePerson = do
personName <- name
personAddress <- fullAddress
pure $ Person{..}
main :: IO ()
main = do
person <- generate fakePerson
print person
```
And on executing them:
$ stack name.hs
Person
{ personName = "Sherryl Steuber"
, personAddress = "Apt. 298 340 Ike Mission, Goldnertown, FL 19488-9259"
}
You would have noticed in the above output that the name and address are
the same as generated before in the GHCi REPL. That's because, by
default all the generated data are deterministic. If you want a
different set of output each time, you would have to modify the random
generator output:
main :: IO ()
main = do
gen <- newStdGen
let settings = setRandomGen gen defaultFakerSettings
person <- generateWithSettings settings fakePerson
print person
And on executing the program, you will get a different output:
``` {.shellsession}
Person
{ personName = "Ned Effertz Sr."
, personAddress = "Suite 158 1580 Schulist Mall, Schulistburgh, NY 15804-3392"
}
```
The above program can be even minimized like this:
``` {.haskell}
main :: IO ()
main = do
let settings = setNonDeterministic defaultFakerSettings
person <- generateWithSettings settings fakePerson
print person
```
Or even better:
``` {.haskell}
main :: IO ()
main = do
person <- generateNonDeterministic fakePerson
print person
```
### Combinators
#### listOf
``` {.haskell}
λ> import Faker.Address
λ> item <- generateNonDeterministic $ listOf 5 country
λ> item
["Ecuador","French Guiana","Faroe Islands","Canada","Armenia"]
```
#### oneOf
``` {.haskell}
λ> item <- generate $ oneof [country, fullAddress]
λ> item
"Suite 599 599 Brakus Flat, South Mason, MT 59962-6876"
```
#### suchThat
``` {.shellsession}
λ> import qualified Faker.Address as AD
λ> item :: Text <- generate $ suchThat AD.country (\x -> (T.length x > 5))
λ> item
"Ecuador"
λ> item :: Text <- generate $ suchThat AD.country (\x -> (T.length x > 8))
λ> item
"French Guiana"
```
For seeing the full list of combinators, see the module documentation of
`Faker.Combinators`.
Comparision with other libraries
--------------------------------
There are two other libraries in the Hackage providing fake data:
- [faker](https://hackage.haskell.org/package/faker-0.0.0.2)
- [fake](https://hackage.haskell.org/package/fake-0.1.1.1)
The problem with both the above libraries is that the library covers
only a very small amount of fake data source. I wanted to have an
equivalent functionality with something like
[faker](https://github.com/stympy/faker). Also, most of the
combinators in this packages has been inspired (read as taken) from
the `fake` library. Also, `fakedata` offers fairly good amount of
support of different locales. Also since we rely on an external data
source, we get free updates and high quality data source with little
effort. Also, it's easier to extend the library with [it's own data
source](https://github.com/psibi/fakedata/blob/master/Development.md#custom-fake-source-support-with-yml-file)
if we want to do it that way.
Acknowledgments
---------------
Benjamin Curtis for his [Ruby faker
library](https://github.com/stympy/faker) from which the data source is
taken from.
Icons made by [Freepik](https://www.flaticon.com/authors/freepik) from
[Flaticon](https://www.flaticon.com/).