First

Author: jsl

.travis.yml

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+language: haskell
+ghc:
+  - 7.4
+  - 7.6
+  - 7.8

LICENSE

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+Copyright (c) 2015 Justin Leitgeb
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# Dotenv files for Haskell
+
+In most applications,
+[configuration should be separated from code](http://12factor.net/config). While
+it usually works well to keep configuration in the environment, there
+are cases where you may want to store configuration in a file outside
+of version control.
+
+"Dotenv" files have become popular for storing configuration,
+especially in development and test environments. In
+[Ruby](https://github.com/bkeepers/dotenv),
+[Python](https://github.com/theskumar/python-dotenv) and
+[Javascript](https://www.npmjs.com/package/dotenv) there are libraries
+to facilitate loading of configuration options from configuration
+files. This library loads configuration to environment variables for
+programs written in Haskell.
+
+## Installation
+
+In most cases you will just add `dotenv` to your cabal file. You can
+also install the library and executable by invoking `cabal install dotenv`.
+
+## Usage
+
+Set configuration variables in a file following the format below:
+
+```
+S3_BUCKET=YOURS3BUCKET
+SECRET_KEY=YOURSECRETKEYGOESHERE
+```
+
+Then, calling Dotenv.load from your Haskell program reads the above
+settings into the environment.:
+
+```haskell
+import Configuration.Dotenv
+Dotenv.loadFile False "/path/to/your/file"
+```
+
+## Configuration
+
+The first argument to `loadFile` specifies whether you want to
+override system settings. `False` means Dotenv will respect
+already-defined variables, and `True` means Dotenv will overwrite
+already-defined variables.
+
+## Advanced Dotenv File Syntax
+
+You can add comments to your Dotenv file, on separate lines or after
+values. Values can be wrapped in single or double quotes. Multi-line
+values can be specified by wrapping the value in double-quotes, and
+using the "\n" character to represent newlines.
+
+The [spec file](spec/Configuration/Dotenv/ParseSpec.hs) is the best
+place to understand the nuances of Dotenv file parsing.
+
+## Command-Line Usage
+
+You can call dotenv from the command line in order to load settings
+from one or more dotenv file before invoking an executable:
+
+```
+dotenv -f mydotenvfile myprogram
+```
+
+Hint: The `env` program in most Unix-like environments prints out the
+current environment settings. By invoking the program `env` in place
+of `myprogram` above you can see what the environment will look like
+after evaluating multiple  Dotenv files.
+
+## Author
+
+Justin Leitgeb
+
+## License
+
+MIT
+
+## Copyright
+
+(C) 2015 Stack Builders Inc.

Setup.hs

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+import Distribution.Simple
+main = defaultMain

dotenv.cabal

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+name:                dotenv
+version:             0.1.0.0
+synopsis:            Loads environment variables from `.env`
+description:
+  .
+  This project is modelled after the Ruby and Python packages for
+  loading files from a dotfile. It can be used as a standalone program,
+  or embedded inside of web servers like Yesod and Snap.
+license:             MIT
+license-file:        LICENSE
+author:              Justin Leitgeb
+maintainer:          [email protected]
+copyright:           2015 Stack Builders Inc.
+category:            Configuration
+build-type:          Simple
+-- extra-source-files:
+cabal-version:       >=1.10
+
+executable dotenv
+  main-is:             Main.hs
+  -- other-modules:
+  -- other-extensions:
+  build-depends:         base >=4.5 && <4.8
+                       , optparse-applicative >=0.11 && <0.12
+                       , parsec >= 3.1.0 && <= 3.2
+                       , process
+
+  hs-source-dirs:      src
+  default-language:    Haskell2010
+
+library
+  exposed-modules:    Configuration.Dotenv.Parse
+                    , Configuration.Dotenv
+
+  build-depends:         base >=4.5 && <4.8
+                       , parsec >= 3.1.0 && <= 3.2
+
+  hs-source-dirs:      src
+  default-language:    Haskell2010
+  ghc-options:         -Wall
+
+
+test-suite dotenv-test
+  type: exitcode-stdio-1.0
+  hs-source-dirs: spec, src
+  main-is: Spec.hs
+  build-depends:       base >=4.5 && <4.8
+                       , parsec >= 3.1.0 && <= 3.2
+
+                       , hspec
+
+  default-language:    Haskell2010
+  ghc-options:         -Wall
+
+source-repository head
+  type:     git
+  location: https://github.com/stackbuilders/dotenv-hs

spec/Configuration/Dotenv/ParseSpec.hs

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+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module Configuration.Dotenv.ParseSpec (spec) where
+
+import Configuration.Dotenv.Parse (configParser)
+
+import Test.Hspec (it, describe, shouldBe, Spec)
+
+import Text.Parsec (ParseError, parse)
+import Text.ParserCombinators.Parsec.Error(errorMessages)
+
+
+spec :: Spec
+spec = describe "parse" $ do
+  it "parses unquoted values" $
+    parseConfig "FOO=bar" `shouldBe` Right [("FOO", "bar")]
+
+  it "parses values with spaces around equal signs" $ do
+    parseConfig "FOO =bar" `shouldBe` Right [("FOO", "bar")]
+    parseConfig "FOO= bar" `shouldBe` Right [("FOO", "bar")]
+    parseConfig "FOO = bar" `shouldBe` Right [("FOO", "bar")]
+
+  it "parses double-quoted values" $
+    parseConfig "FOO=\"bar\"" `shouldBe` Right [("FOO", "bar")]
+
+  it "parses single-quoted values" $
+    parseConfig "FOO='bar'" `shouldBe` Right [("FOO", "bar")]
+
+  it "parses escaped double quotes" $
+    parseConfig "FOO=\"escaped\\\"bar\"" `shouldBe` Right [("FOO", "escaped\"bar")]
+
+  it "parses empty values" $
+    parseConfig "FOO=" `shouldBe` Right [("FOO", "")]
+
+  it "does not parse if line format is incorrect" $
+    isLeft (parseConfig "lol$wut") `shouldBe` True
+
+  it "expands newlines in quoted strings" $
+    parseConfig "FOO=\"bar\nbaz\"" `shouldBe` Right [("FOO", "bar\nbaz")]
+
+  it "parses variables with '.' in the name" $
+    parseConfig "FOO.BAR=foobar" `shouldBe` Right [("FOO.BAR", "foobar")]
+
+  it "strips unquoted values" $
+    parseConfig "foo=bar " `shouldBe` Right [("foo", "bar")]
+
+  it "ignores empty lines" $
+    parseConfig "\n \t  \nfoo=bar\n \nfizz=buzz" `shouldBe`
+    Right [("foo", "bar"), ("fizz", "buzz")]
+
+  it "ignores inline comments" $
+    parseConfig "FOO=bar # this is foo" `shouldBe` Right [("FOO", "bar")]
+
+  it "allows # in quoted values" $
+    parseConfig "foo=\"bar#baz\" # comment" `shouldBe`
+    Right [("foo", "bar#baz")]
+
+  it "ignores comment lines" $
+    parseConfig "\n\n\n # HERE GOES FOO \nfoo=bar" `shouldBe`
+    Right [("foo", "bar")]
+
+
+isLeft :: Either a b -> Bool
+isLeft ( Left _ ) = True
+isLeft _          = False
+
+
+instance Eq ParseError where
+  a == b = errorMessages a == errorMessages b
+
+parseConfig :: String -> Either ParseError [(String, String)]
+parseConfig = parse configParser "(unknown)"

spec/Configuration/DotenvSpec.hs

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+module Configuration.DotenvSpec (spec) where
+
+import Configuration.Dotenv (load, loadFile)
+
+import Test.Hspec (it, describe, shouldBe, Spec)
+
+import System.Environment (lookupEnv, setEnv, unsetEnv)
+
+spec :: Spec
+spec = do
+  describe "load" $ do
+    it "loads the given list of configuration options to the environment" $ do
+      beforeSet <- lookupEnv "foo"
+      beforeSet `shouldBe` Nothing
+
+      load False [("foo", "bar")]
+
+      afterSet <- lookupEnv "foo"
+      afterSet `shouldBe` Just "bar"
+
+      unsetEnv "foo" -- unset tested vars to clean test state
+
+    it "preserves existing settings when overload is false" $ do
+      setEnv "foo" "preset"
+
+      load False [("foo", "new setting")]
+
+      afterSet <- lookupEnv "foo"
+      afterSet `shouldBe` Just "preset"
+
+      unsetEnv "foo" -- unset tested vars to clean test state
+
+    it "overrides existing settings when overload is true" $ do
+      setEnv "foo" "preset"
+
+      load True [("foo", "new setting")]
+
+      afterSet <- lookupEnv "foo"
+      afterSet `shouldBe` Just "new setting"
+
+      unsetEnv "foo" -- unset tested vars to clean test state
+
+  describe "loadFile" $ do
+    it "loads the configuration options to the environment from a file" $ do
+      beforeSet <- lookupEnv "DOTENV"
+      beforeSet `shouldBe` Nothing
+
+      loadFile False "spec/fixtures/.dotenv"
+
+      afterSet <- lookupEnv "DOTENV"
+      afterSet `shouldBe` Just "true"
+
+      unsetEnv "DOTENV"
+
+    it "respects predefined settings when overload is false" $ do
+      setEnv "DOTENV" "preset"
+
+      loadFile False "spec/fixtures/.dotenv"
+
+      afterSet <- lookupEnv "DOTENV"
+      afterSet `shouldBe` Just "preset"
+
+      unsetEnv "DOTENV"
+
+    it "overrides predefined settings when overload is true" $ do
+      setEnv "DOTENV" "preset"
+
+      loadFile True "spec/fixtures/.dotenv"
+
+      afterSet <- lookupEnv "DOTENV"
+      afterSet `shouldBe` Just "true"
+
+      unsetEnv "DOTENV"

spec/Spec.hs

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+{-# OPTIONS_GHC -F -pgmF hspec-discover #-}

spec/fixtures/.dotenv

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+DOTENV=true

src/Configuration/Dotenv.hs

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+module Configuration.Dotenv (load, loadFile) where
+
+import System.Environment (lookupEnv, setEnv)
+
+import Configuration.Dotenv.Parse (configParser)
+
+import Text.Parsec (parse)
+
+-- | Loads the given list of options into the environment.
+-- Any existing settings will take priority.
+load ::
+  Bool -- ^ Override existing settings?
+
+  -- ^ A list of tuples in the form (key, value) to be set in the environment
+  -> [(String, String)]
+  -> IO ()
+load override = mapM_ (applySetting override)
+
+-- | Loads the options in the given file to the environment.
+loadFile ::
+  Bool        -- ^ Override existing settings?
+  -> FilePath -- ^ A file containing options to load into the environment
+  -> IO ()
+loadFile override f = do
+  contents <- readFile f
+
+  case parse configParser f contents of
+    Left e        -> error $ "Failed to read file" ++ show e
+    Right options -> load override options
+
+
+applySetting :: Bool -> (String, String) -> IO ()
+applySetting override (key, value) =
+  if override then
+    setEnv key value
+
+  else do
+    res <- lookupEnv key
+
+    case res of
+      Nothing -> setEnv key value
+      Just _  -> return ()