Add examples

Author: koladilip

difference-of-squares/README.md

@@ -0,0 +1,77 @@
+# Difference Of Squares
+
+Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.
+
+The square of the sum of the first ten natural numbers is
+(1 + 2 + ... + 10)² = 55² = 3025.
+
+The sum of the squares of the first ten natural numbers is
+1² + 2² + ... + 10² = 385.
+
+Hence the difference between the square of the sum of the first
+ten natural numbers and the sum of the squares of the first ten
+natural numbers is 3025 - 385 = 2640.
+
+You are not expected to discover an efficient solution to this yourself from
+first principles; research is allowed, indeed, encouraged. Finding the best
+algorithm for the problem is a key skill in software engineering.
+
+
+## Getting Started
+
+Please refer to the [installation](https://exercism.io/tracks/haskell/installation)
+and [learning](https://exercism.io/tracks/haskell/learning) help pages.
+
+## Running the tests
+
+To run the test suite, execute the following command:
+
+```bash
+stack test
+```
+
+#### If you get an error message like this...
+
+```
+No .cabal file found in directory
+```
+
+You are probably running an old stack version and need
+to upgrade it.
+
+#### Otherwise, if you get an error message like this...
+
+```
+No compiler found, expected minor version match with...
+Try running "stack setup" to install the correct GHC...
+```
+
+Just do as it says and it will download and install
+the correct compiler version:
+
+```bash
+stack setup
+```
+
+## Running *GHCi*
+
+If you want to play with your solution in GHCi, just run the command:
+
+```bash
+stack ghci
+```
+
+## Feedback, Issues, Pull Requests
+
+The [exercism/haskell](https://github.com/exercism/haskell) repository on
+GitHub is the home for all of the Haskell exercises.
+
+If you have feedback about an exercise, or want to help implementing a new
+one, head over there and create an issue.  We'll do our best to help you!
+
+## Source
+
+Problem 6 at Project Euler [http://projecteuler.net/problem=6](http://projecteuler.net/problem=6)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

difference-of-squares/difference-of-squares.cabal

@@ -0,0 +1,36 @@
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.33.0.
+--
+-- see: https://github.com/sol/hpack
+--
+-- hash: e27ffc942adce007d6b37d5bdc51acfedefcefa9ee2e58e92e6b398a73196bdf
+
+name:           difference-of-squares
+version:        1.2.0.7
+build-type:     Simple
+
+library
+  exposed-modules:
+      Squares
+  other-modules:
+      Paths_difference_of_squares
+  hs-source-dirs:
+      src
+  ghc-options: -Wall
+  build-depends:
+      base
+  default-language: Haskell2010
+
+test-suite test
+  type: exitcode-stdio-1.0
+  main-is: Tests.hs
+  other-modules:
+      Paths_difference_of_squares
+  hs-source-dirs:
+      test
+  build-depends:
+      base
+    , difference-of-squares
+    , hspec
+  default-language: Haskell2010

difference-of-squares/package.yaml

@@ -0,0 +1,21 @@
+name: difference-of-squares
+version: 1.2.0.7
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: Squares
+  source-dirs: src
+  ghc-options: -Wall
+  # dependencies:
+  # - foo       # List here the packages you
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - difference-of-squares
+      - hspec

difference-of-squares/src/Squares.hs

@@ -0,0 +1,13 @@
+module Squares (difference, squareOfSum, sumOfSquares) where
+
+difference :: Integral a => a -> a
+difference n = (squareOfSum n) - (sumOfSquares n)
+
+square :: Integral a => a -> a
+square n = n * n
+
+squareOfSum :: Integral a => a -> a
+squareOfSum n = square (div (n * (n+1)) 2) ;
+
+sumOfSquares :: Integral a => a -> a
+sumOfSquares n = div (n * ((n+1) * ((2*n) + 1)))  6

difference-of-squares/stack.yaml

@@ -0,0 +1 @@
+resolver: lts-15.8

difference-of-squares/stack.yaml.lock

@@ -0,0 +1,12 @@
+# This file was autogenerated by Stack.
+# You should not edit this file by hand.
+# For more information, please see the documentation at:
+#   https://docs.haskellstack.org/en/stable/lock_files
+
+packages: []
+snapshots:
+- completed:
+    size: 492015
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/15/8.yaml
+    sha256: 926bc3d70249dd0ba05277ff00943c0addb35b627cb641752669e7cf771310d0
+  original: lts-15.8

difference-of-squares/test/Tests.hs

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+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFastFail, defaultConfig, hspecWith)
+
+import Squares (difference, squareOfSum, sumOfSquares)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFastFail = True} specs
+
+specs :: Spec
+specs = do
+
+    describe "squareOfSum" $ do
+      it "square of sum 1"   $ squareOfSum   1 `shouldBe`        1
+      it "square of sum 5"   $ squareOfSum   5 `shouldBe`      225
+      it "square of sum 100" $ squareOfSum 100 `shouldBe` 25502500
+
+    describe "sumOfSquares" $ do
+      it "sum of squares 1"   $ sumOfSquares   1 `shouldBe`      1
+      it "sum of squares 5"   $ sumOfSquares   5 `shouldBe`     55
+      it "sum of squares 100" $ sumOfSquares 100 `shouldBe` 338350
+
+    describe "differenceOfSquares" $ do
+      it "difference of squares 1"   $ difference   1 `shouldBe`        0
+      it "difference of squares 5"   $ difference   5 `shouldBe`      170
+      it "difference of squares 100" $ difference 100 `shouldBe` 25164150
+
+    -- Track-specific tests.
+
+    describe "Integral tests" $ do
+
+      describe "squareOfSum" $ do
+
+        it "squareOfSum (6 :: Int)" $
+          squareOfSum (6 :: Int)
+          `shouldBe` (441 :: Int)
+
+        it "squareOfSum (7 :: Integer)" $
+          squareOfSum (7 :: Integer)
+          `shouldBe` (784 :: Integer)
+
+      describe "sumOfSquares" $ do
+
+        it "sumOfSquares (8 :: Int)" $
+          sumOfSquares (8 :: Int)
+          `shouldBe` (204 :: Int)
+
+        it "sumOfSquares (9 :: Integer)" $
+          sumOfSquares (9 :: Integer)
+          `shouldBe` (285 :: Integer)
+
+      describe "difference" $ do
+
+        it "difference (11 :: Int)" $
+          difference (11 :: Int)
+          `shouldBe` (3850 :: Int)
+
+        it "difference (12 :: Integer)" $
+          difference (12 :: Integer)
+          `shouldBe` (5434 :: Integer)
+
+      {-
+      describe "huge difference" $
+        it "difference (1234567890 :: Integer)" $
+          difference (1234567890 :: Integer)
+          `shouldBe` (580764307309260838625720836817589660 :: Integer)
+      -}

general-examples/search-file

@@ -19,13 +19,6 @@ printSearchResult (a, Just _) = do
 printSearchResult (a, Nothing) = do
     print $ a <> " is not found"
 
-printSearchResults :: [(String, Maybe Int)] -> IO ()                  -- optional type signature
-printSearchResults [] = do
-    return ()
-
-printSearchResults (result:otherResults) = do
-    printSearchResult result
-    printSearchResults otherResults
 
 split :: [Char] -> [Char] -> [[Char]]
 split [] _  = []
@@ -49,4 +42,4 @@ main = do
     contents <- readFile filePath
     let fileWords = split contents ", ?;.\t\n\r"
     let searchResults = search inputWords fileWords 
-    printSearchResults searchResults
+    mapM_ (\r -> printSearchResult r) searchResults