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authorBenjamin Barenblat <benjamin@barenblat.name>2012-12-26 21:56:42 -0600
committerBenjamin Barenblat <benjamin@barenblat.name>2013-01-28 15:03:56 -0500
commitf9c68cad1273d6d7b2373600b8d6d11080b7863a (patch)
tree0ac6144d129c441cb93522cfcfa8ef4037a494ab
Initial commitHEADmaster
-rw-r--r--.gitignore8
-rw-r--r--DBpedia.hs90
-rw-r--r--HACKING27
-rw-r--r--LICENSE675
-rw-r--r--Main.hs58
-rw-r--r--RequestMethod.hs42
-rw-r--r--SamplePlugin.hs30
-rw-r--r--Setup.hs2
-rw-r--r--ageOf.cabal30
9 files changed, 962 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
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--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,8 @@
+# .gitignore for ageOf -*- conf -*-
+
+# Editor backup files
+*~
+
+# cabal-dev files
+cabal-dev/
+dist/
diff --git a/DBpedia.hs b/DBpedia.hs
new file mode 100644
index 0000000..1f4d74b
--- /dev/null
+++ b/DBpedia.hs
@@ -0,0 +1,90 @@
+{- DBpedia.hs -- requesting ages from DBpedia
+Copyright (C) 2012 Benjamin Barenblat <benjamin@barenblat.name>
+
+This module is a part of ageOf.
+
+ageOf is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+ageOf is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+ageOf. If not, see <http://www.gnu.org/licenses/>. -}
+
+module DBpedia (dbpedia) where
+
+import Control.Monad (void)
+import Database.HSparql.Connection
+import Database.HSparql.QueryGenerator
+import qualified Data.Time as Time (Day, parseTime)
+import qualified Data.RDF as RDF (Node(..), LValue(..))
+import qualified Data.Text as Text (unpack)
+import System.CurrentLocale (currentLocale)
+import System.Locale (TimeLocale)
+
+import RequestMethod (RequestMethod(BirthDateFunction))
+
+-- The DBpedia plugin, defined by the single function 'getBirthDate'.
+dbpedia :: RequestMethod
+dbpedia = BirthDateFunction getBirthDate
+
+getBirthDate :: String -> IO (Maybe Time.Day)
+getBirthDate name = do
+ locale <- currentLocale
+ response <- askDBpedia $ selectBirthDate name
+ return $ case response of
+ Nothing -> Nothing
+ Just Unbound -> Nothing
+ Just (Bound node) -> parseAsDate locale node
+
+{- Generates a DBpedia SELECT query for a person's birth date. You can see the
+generated query by running 'putStrLn $ createSelectQuery simpleSelect'. -}
+selectBirthDate :: String -> Query SelectQuery
+selectBirthDate name = do
+ -- Variables
+ page <- var
+ birthDate <- var
+ -- Prefixes
+ dbpprop <- prefix "dbprop" $ iriRef "http://dbpedia.org/property/"
+ rdfs <- prefix "rdfs" $ iriRef "http://www.w3.org/2000/01/rdf-schema#"
+ -- Okay, here we go.
+ let query = SelectQuery [birthDate]
+ void $ triple page (rdfs .:. "label") (name, "en")
+ void $ triple page (dbpprop .:. "birthDate") birthDate
+ return query
+
+{- Runs a SELECT query for a single variable on DBpedia, returning the first
+possible match. -}
+askDBpedia :: Query SelectQuery -> IO (Maybe BindingValue)
+askDBpedia q = do
+ result <- selectQuery "http://dbpedia.org/sparql" q
+ return $ case result of
+ Just ([x]:_) -> Just x
+ Just ((_:_):_) -> error "got more than one bound variable"
+ _ -> Nothing
+
+-- Parses an RDF literal as a date.
+parseAsDate :: TimeLocale -> RDF.Node -> Maybe Time.Day
+parseAsDate locale (RDF.LNode node) =
+ let value =
+ case node of
+ RDF.PlainL v -> v
+ RDF.PlainLL v _lang -> v
+ RDF.TypedL v _type -> v
+ in parseXMLSchemaDate locale $ Text.unpack value
+parseAsDate _ _ = Nothing
+
+{- Parses a date somewhat as described in the XML Schema
+<http://www.w3.org/TR/xmlschema-2/#date>. TODO: Handle large (>12-hour) time
+zone offsets correctly. TODO: Handle BCE (negative) years correctly. -}
+parseXMLSchemaDate :: TimeLocale -> String -> Maybe Time.Day
+parseXMLSchemaDate locale dateString =
+ let expectedFormat =
+ if length dateString > length "YYYY-MM-DD"
+ then "%F%z" -- There's a time zone.
+ else "%F"
+ in Time.parseTime locale expectedFormat dateString
diff --git a/HACKING b/HACKING
new file mode 100644
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+++ b/HACKING
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+ ageOf architecture
+
+ageOf determines somebody's age by querying one or more sources on the
+Internet. Since there are hundreds of different sites that catalogue the ages
+of famous (and not-so-famous) people, ageOf uses a plugin-based architecture.
+Each source gets its own plugin, and then ageOf queries each source in turn.
+The first source that gives back an age wins.
+
+The Haskell idiom to do a plugin-based architecture is to define a plugin data
+type, and that's what I've done here. The 'RequestMethod' type represents a
+plugin--a single function that takes the name of a person and returns
+(depending on which constructor you use) his/her age or date of birth. To
+define a new plugin, you thus need to create a new module which exports a
+'RequestMethod' type.
+
+There are currently two plugins packaged with ageOf (though that may change in
+the future). One is a sample plugin--it knows when Simon Peyton Jones (the
+author of Haskell) was born, and that's it; use it as a skeleton for writing
+your own plugins. The second plugin is a real, nontrivial plugin that uses
+DBpedia (the Semantic Web mirror of Wikipedia) to determine the age of anybody
+whose age is stored on Wikipedia.
+
+
+Local Variables:
+mode: text
+fill-column: 79
+End:
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..12fc7e0
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,675 @@
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diff --git a/Main.hs b/Main.hs
new file mode 100644
index 0000000..c08ac83
--- /dev/null
+++ b/Main.hs
@@ -0,0 +1,58 @@
+{- Main.hs -- main entry point
+Copyright (C) 2012 Benjamin Barenblat <benjamin@barenblat.name>
+
+This module is a part of ageOf.
+
+ageOf is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+ageOf is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+ageOf. If not, see <http://www.gnu.org/licenses/>. -}
+
+module Main where
+
+import Control.Monad (foldM)
+import System.Environment (getArgs, getProgName)
+import System.Exit (ExitCode(..), exitWith)
+import Text.Printf (printf)
+
+import RequestMethod (RequestMethod, getAge)
+import DBpedia (dbpedia)
+import SamplePlugin (samplePlugin)
+
+-- The plugins we're going to query, in order of preference.
+plugins :: [RequestMethod]
+plugins = [ samplePlugin
+ , dbpedia ]
+
+main :: IO ()
+main = getArgs >>= go >>= exitWith
+
+go :: [String] -> IO ExitCode
+go (name : []) = do
+ age <- getAgeWith plugins name
+ case age of
+ Nothing -> return $ ExitFailure 1
+ Just n -> print n >> return ExitSuccess
+go _ = usage >> return (ExitFailure 1)
+
+{- The workhorse function. Given a list of 'RequestMethod's, 'getAgeWith'
+tries to look up 'name' in each one. As soon as a match succeeds, it returns
+the age. -}
+getAgeWith :: [RequestMethod] -> String -> IO (Maybe Integer)
+getAgeWith methods name =
+ foldM maybeTryNextMethod Nothing methods
+ where maybeTryNextMethod :: Maybe Integer -> RequestMethod -> IO (Maybe Integer)
+ maybeTryNextMethod v@(Just _) _ = return v
+ maybeTryNextMethod Nothing method = getAge method name
+
+usage :: IO ()
+usage = do
+ programName <- getProgName
+ printf "usage: %s <name>\n" programName
diff --git a/RequestMethod.hs b/RequestMethod.hs
new file mode 100644
index 0000000..0828b13
--- /dev/null
+++ b/RequestMethod.hs
@@ -0,0 +1,42 @@
+{- RequestMethod.hs -- how to request somebody's age off the Internet
+Copyright (C) 2012 Benjamin Barenblat <benjamin@barenblat.name>
+
+This module is a part of ageOf.
+
+ageOf is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+ageOf is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+ageOf. If not, see <http://www.gnu.org/licenses/>. -}
+
+module RequestMethod ( RequestMethod(..)
+ , getAge
+ ) where
+
+import Control.Applicative ((<$>))
+import Data.Time
+
+data RequestMethod = AgeFunction (String -> IO (Maybe Integer))
+ | BirthDateFunction (String -> IO (Maybe Day))
+
+getAge :: RequestMethod -> String -> IO (Maybe Integer)
+getAge (AgeFunction f) name = f name
+getAge (BirthDateFunction f) name = do
+ today <- localDay <$> zonedTimeToLocalTime <$> getZonedTime
+ maybeDate <- f name
+ return $ diffYears today <$> maybeDate
+
+diffYears :: Day -> Day -> Integer
+new `diffYears` old =
+ let (oldYear, _, _) = toGregorian old
+ (newYear, _, _) = toGregorian new in
+ let yearsDelta = newYear - oldYear in
+ if addGregorianYearsRollOver yearsDelta old > new
+ then yearsDelta - 1
+ else yearsDelta
diff --git a/SamplePlugin.hs b/SamplePlugin.hs
new file mode 100644
index 0000000..3a795a8
--- /dev/null
+++ b/SamplePlugin.hs
@@ -0,0 +1,30 @@
+{- SamplePlugin.hs -- a sample request plugin
+Copyright (C) 2012 Benjamin Barenblat <benjamin@barenblat.name>
+
+This module is a part of ageOf.
+
+ageOf is free software: you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation, either version 3 of the License, or (at your option) any later
+version.
+
+ageOf is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along with
+ageOf. If not, see <http://www.gnu.org/licenses/>. -}
+
+module SamplePlugin (samplePlugin) where
+
+import Data.Time (Day, fromGregorian)
+
+import RequestMethod (RequestMethod(BirthDateFunction))
+
+-- The sample plugin, defined by the single function 'getBirthDate'.
+samplePlugin :: RequestMethod
+samplePlugin = BirthDateFunction getBirthDate
+
+getBirthDate :: String -> IO (Maybe Day)
+getBirthDate "Simon Peyton Jones" = return $ Just $ fromGregorian 1958 1 18
+getBirthDate _ = return Nothing
diff --git a/Setup.hs b/Setup.hs
new file mode 100644
index 0000000..9a994af
--- /dev/null
+++ b/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/ageOf.cabal b/ageOf.cabal
new file mode 100644
index 0000000..17382d1
--- /dev/null
+++ b/ageOf.cabal
@@ -0,0 +1,30 @@
+name: ageOf
+version: 0.1.0
+license: GPL-3
+license-file: LICENSE
+author: Benjamin Barenblat
+maintainer: benjamin@barenblat.name
+category: Web
+build-type: Simple
+cabal-version: >=1.8
+
+executable ageOf
+ main-is: Main.hs
+ other-modules: DBpedia
+ , RequestMethod
+ , SamplePlugin
+ ghc-options: -Wall
+ build-depends: base ==4.5.*
+ , current-locale ==0.*
+ , hsparql ==0.2.*
+ , old-locale ==1.*
+ , rdf4h ==1.1.*
+ , text ==0.11.*
+ , time ==1.4.*
+
+
+-- Local Variables:
+-- mode: Haskell-Cabal
+-- fill-column: 70
+-- indent-tabs-mode: nil
+-- End: