Display time taken to compute solutions

README.md

@@ -18,6 +18,7 @@ Example for solving problem 72:
 $ cabal run 72
 Preprocessing executable 'problem' for project-euler-0.1.0.0...
 303963552391
+961.09 ms
 ```
 
 # Notes

project-euler.cabal

@@ -22,14 +22,14 @@ source-repository head
 executable problem
   hs-source-dirs:     src
   main-is:            Main.hs
-  build-depends:      arithmoi, base, containers, digits, memoize, primes, NumberSieves
+  build-depends:      arithmoi, base, clock, containers, digits, formatting, memoize, primes, NumberSieves
   ghc-options:        -Wall -Werror -O2
   default-extensions: NumDecimals
 
 test-suite test-all
   hs-source-dirs:     src, test
   type:               exitcode-stdio-1.0
   main-is:            TestAll.hs
-  build-depends:      arithmoi, base, containers, digits, memoize, primes, NumberSieves, HUnit, Cabal >= 1.9.2
+  build-depends:      arithmoi, base, clock, containers, digits, formatting, memoize, primes, NumberSieves, HUnit, Cabal >= 1.9.2
   ghc-options:        -Wall -Werror -O2
   default-extensions: NumDecimals

src/Main.hs

@@ -1,6 +1,10 @@
+{-# LANGUAGE OverloadedStrings #-}
+
 module Main where
 
 import qualified Data.Map as M
+import Formatting
+import Formatting.Clock
 import ProjectEuler.Problem001
 import ProjectEuler.Problem002
 import ProjectEuler.Problem004
@@ -41,6 +45,7 @@ import ProjectEuler.Problem214
 import ProjectEuler.Problem225
 import System.Environment (getArgs)
 import System.Exit (exitSuccess)
+import System.Clock
 
 solutions :: M.Map Integer Integer
 solutions = M.fromList [
@@ -92,9 +97,14 @@ main = do
     case args of
         ["--help"] -> usage >> exitSuccess
         ["-h"] -> usage >> exitSuccess
-        [number] -> case solution (read number :: Integer) of
-            Just result -> print result
-            Nothing -> putStrLn "There is no solution yet for this problem"
+        [number] -> do
+            let n = read number :: Integer
+            start <- getTime Monotonic
+            case solution n of
+                Just result -> print result
+                Nothing -> putStrLn "There is no solution yet for this problem"
+            end <- getTime Monotonic
+            fprint (timeSpecs % "\n") start end
         _ -> usage >> exitSuccess
     where
         usage = putStrLn "Usage: cabal run problem [number]"