Add first prototype

.gitignore

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+# Vim swap files
+*.sw?
+
+# Haskell unversioned stuff
+dist
+dist-*
+cabal-dev
+*.o
+*.hi
+*.hie
+*.chi
+*.chs.h
+*.dyn_o
+*.dyn_hi
+.hpc
+.hsenv
+.cabal-sandbox/
+cabal.sandbox.config
+*.prof
+*.aux
+*.hp
+*.eventlog
+.stack-work/
+cabal.project.local
+cabal.project.local~
+.HTF/
+.ghc.environment.*

CHANGELOG.md

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+# Revision history for trivialini
+
+## 0.1.0.0 -- 2021-02-22
+
+* First version. Released on an unsuspecting world.

LICENSE

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+Copyright (c) 2021 Mirko Westermeier
+
+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.

Setup.hs

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+import Distribution.Simple
+main = defaultMain

src/Trivialini.hs

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+-- | Ultra light weight ini file parser
+module Trivialini (config, configFile) where
+
+import Data.Map     (Map, keys, empty, insert, (!))
+import Text.Regex   (mkRegex, matchRegex)
+
+--
+--  Data structure and accessors
+--
+
+-- data structure for "ini" file representation
+data Config = Empty | Config String (Map String String) Config
+
+instance Show Config where
+    show Empty = ""
+    show (Config sec defs rest) = secLn ++ defLns ++ "\n" ++ show rest
+        where
+            secLn   = "[" ++ sec ++ "]\n"
+            defLns  = concatMap def $ keys defs
+            def key = key ++ " = " ++ defs ! key ++ "\n"
+
+-- Extract the list of all section names
+sections :: Config -> [String]
+sections Empty                  = []
+sections (Config name _ rest)   = name : sections rest
+
+-- Extract the map of config values for a given section name
+section :: Config -> String -> Map String String
+section Empty _                         = empty
+section (Config name map rest) query
+    | name == query                     = map
+    | otherwise                         = section rest query
+
+-- Extract a configuration data value for a given section and key
+value :: Config -> String -> String -> String
+value conf sec key = s ! key
+    where s = section conf sec
+
+--
+--  Parsing data structure from text file
+--
+
+readConfig :: String -> Config
+-- Preparation of config parsing
+readConfig = rc "default" empty . lines
+
+rc :: String -> Map String String -> [String] -> Config
+-- Build config data line by line (first argument is the current section)
+rc sec values [] = Config sec values Empty
+rc sec values (line:lines) = case chkSec line of
+
+    -- It's a section
+    (Just [newS]) -> Config sec values $ rc newS empty lines
+
+    -- It's not a section
+    Nothing -> case chkKV line of
+
+        -- It's a key value assignment
+        (Just [key, value]) -> rc sec (insert key value values) lines
+
+        -- Neither: ignore
+        Nothing -> rc sec values lines
+
+    where
+        chkSec  = matchRegex (mkRegex "^\\[(.+)\\]")
+        chkKV   = matchRegex (mkRegex "^(\\S+)\\s+=\\s+(.*)$")
+
+--
+--  Public interface
+--
+
+config :: String -> String -> String -> String
+-- ^Return the config value for a given section and key from the given config
+config = value . readConfig
+
+configFile :: String -> String -> String -> IO String
+-- ^Return the config file value for a given section and key
+configFile file sec key = do
+    content <- readFile file
+    return $ config content sec key

trivialini.cabal

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+-- Initial trivialini.cabal generated by cabal init.  For further
+-- documentation, see http://haskell.org/cabal/users-guide/
+
+name:                trivialini
+version:             0.1.0.0
+synopsis:            Ultra light weight ini file parser
+-- description:
+homepage:            https://github.com/memowe/trivialini
+license:             MIT
+license-file:        LICENSE
+author:              Mirko Westermeier
+maintainer:          [email protected]
+-- copyright:
+category:            Text
+build-type:          Simple
+extra-source-files:  CHANGELOG.md
+cabal-version:       >=1.10
+
+library
+  exposed-modules:
+    Trivialini
+  -- other-modules:
+  -- other-extensions:
+  build-depends:
+    base >=4.12 && <4.13,
+    containers,
+    regex-compat
+  hs-source-dirs:      src
+  default-language:    Haskell2010