Add initial revision, README and TODO list

README.md

@@ -1 +1,20 @@
-# pi-digits
+# pi-digits
+
+Calculate requested digits of Pi.
+
+Built using [The BBP Algorithm for Pi](http://www.davidhbailey.com/dhbpapers/bbp-alg.pdf).
+
+## Building
+
+Install `stack`, then run `stack build` from inside the repository.
+
+## Running
+
+Run `stack exec pi-digits-exe`, or execute the binary found in `./.stack-work/install/`.
+
+## TODO
+
+- Add a function for converting results to decimal.
+- Implement a faster mod operation, to allow for larger numbers (like 12345678901234567890). It will likely be implemented with the algorithm explained in the paper.
+- Replace the mess in `prompt` with a monad.
+- Implement threading?

Setup.hs

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+import Distribution.Simple
+main = defaultMain

app/Main.hs

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+module Main where
+import Numeric (showHex)
+import Data.List (isInfixOf, genericIndex)
+import Data.List.Split(splitOn)
+import Text.Read (readMaybe)
+import System.IO (hFlush, stdout)
+
+hexPi :: Integer -> Char
+hexPi n =
+  let
+    summation = (4 * sumPi n 1) - (2 * sumPi n 4) - (sumPi n 5) - (sumPi n 6)
+    skimmedSum = summation - (fromIntegral (floor summation :: Integer))
+  in
+    showHex (floor (16 * skimmedSum) :: Integer) "" !! 0
+
+sumPi :: Integer -> Integer -> Double
+sumPi n x =
+  let
+    summation1 = [(fromIntegral ((16^(n-k) `mod` ((8*k)+x)))) / (fromIntegral ((8*k)+x)) | k <- [0..n]]
+    -- 5000 is used in place of Infinity. This value drops off quickly, so no need to go too far.
+    summation2 = [16^^(n-k) / (fromIntegral ((8*k)+x)) | k <- [(n+1)..5000]]
+  in
+    sum $ summation1 ++ summation2
+
+rangePi :: Maybe Integer -> Maybe Integer -> IO ()
+rangePi num1 num2 = do
+  case (num1, num2) of
+    (Just one, Just two) ->
+      if one >= two then
+        putStrLn "Please give a proper range."
+      else
+        putStrLn $ foldr (:) [] (drop (fromIntegral one) . take (fromIntegral two) $ hexDigits)
+    (_,_) -> putStrLn "Error: Please give an Integer (ex: 3) or a range (ex: 3..5)."
+
+prompt :: IO ()
+prompt = do
+  putStr ":: "
+  hFlush stdout
+  response <- getLine
+  -- Check if response is range, or single digit.
+  if (isInfixOf ".." response) then
+    let
+      range = splitOn ".." response
+    in
+      rangePi (readMaybe $ range !! 0 :: Maybe Integer) (readMaybe $ range !! 1 :: Maybe Integer)
+    else do
+      case (readMaybe response :: Maybe Integer) of
+        Nothing -> putStrLn "Error: Please give an Integer (ex: 3) or a range (ex: 3..5)."
+        Just x -> putStrLn $ hexDigits `genericIndex` x :[]
+  prompt
+
+-- Establish the list of answers
+hexDigits :: [Char]
+hexDigits = [hexPi x | x <- [0..]]
+
+main :: IO ()
+main = do
+  putStrLn "Enter a digit or range (Ctrl-C to exit)"
+  prompt 

pi-digits.cabal

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+name:                pi-digits
+version:             0.1.0.0
+-- synopsis:
+-- description:
+homepage:            https://github.com/githubuser/pi-digits#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Author name here
+maintainer:          example@example.com
+copyright:           2017 Author name here
+category:            Web
+build-type:          Simple
+extra-source-files:  README.md
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Lib
+  build-depends:       base >= 4.7 && < 5
+  default-language:    Haskell2010
+
+executable pi-digits-exe
+  hs-source-dirs:      app
+  main-is:             Main.hs
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  build-depends:       base
+                     , pi-digits
+                     , split
+  default-language:    Haskell2010
+
+test-suite pi-digits-test
+  type:                exitcode-stdio-1.0
+  hs-source-dirs:      test
+  main-is:             Spec.hs
+  build-depends:       base
+                     , pi-digits
+  ghc-options:         -threaded -rtsopts -with-rtsopts=-N
+  default-language:    Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/githubuser/pi-digits

src/Lib.hs

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+module Lib
+    ( someFunc
+    ) where
+
+someFunc :: IO ()
+someFunc = putStrLn "someFunc"

stack.yaml

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+# This file was automatically generated by 'stack init'
+#
+# Some commonly used options have been documented as comments in this file.
+# For advanced use and comprehensive documentation of the format, please see:
+# https://docs.haskellstack.org/en/stable/yaml_configuration/
+
+# Resolver to choose a 'specific' stackage snapshot or a compiler version.
+# A snapshot resolver dictates the compiler version and the set of packages
+# to be used for project dependencies. For example:
+#
+# resolver: lts-3.5
+# resolver: nightly-2015-09-21
+# resolver: ghc-7.10.2
+# resolver: ghcjs-0.1.0_ghc-7.10.2
+# resolver:
+#  name: custom-snapshot
+#  location: "./custom-snapshot.yaml"
+resolver: lts-9.2
+
+# User packages to be built.
+# Various formats can be used as shown in the example below.
+#
+# packages:
+# - some-directory
+# - https://example.com/foo/bar/baz-0.0.2.tar.gz
+# - location:
+#    git: https://github.com/commercialhaskell/stack.git
+#    commit: e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+# - location: https://github.com/commercialhaskell/stack/commit/e7b331f14bcffb8367cd58fbfc8b40ec7642100a
+#   extra-dep: true
+#  subdirs:
+#  - auto-update
+#  - wai
+#
+# A package marked 'extra-dep: true' will only be built if demanded by a
+# non-dependency (i.e. a user package), and its test suites and benchmarks
+# will not be run. This is useful for tweaking upstream packages.
+packages:
+- .
+# Dependency packages to be pulled from upstream that are not in the resolver
+# (e.g., acme-missiles-0.3)
+extra-deps: [split-0.2.3.2]
+
+# Override default flag values for local packages and extra-deps
+flags: {}
+
+# Extra package databases containing global packages
+extra-package-dbs: []
+
+# Control whether we use the GHC we find on the path
+# system-ghc: true
+#
+# Require a specific version of stack, using version ranges
+# require-stack-version: -any # Default
+# require-stack-version: ">=1.5"
+#
+# Override the architecture used by stack, especially useful on Windows
+# arch: i386
+# arch: x86_64
+#
+# Extra directories used by stack for building
+# extra-include-dirs: [/path/to/dir]
+# extra-lib-dirs: [/path/to/dir]
+#
+# Allow a newer minor version of GHC than the snapshot specifies
+# compiler-check: newer-minor

test/Spec.hs

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+main :: IO ()
+main = putStrLn "Test suite not yet implemented"