diff options
author | Vincent Ambo <tazjin@google.com> | 2019-07-04T10·18+0100 |
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committer | Vincent Ambo <tazjin@google.com> | 2019-07-04T10·18+0100 |
commit | f723b8b878a3c4a4687b9e337a875500bebb39b1 (patch) | |
tree | e85204cf042c355e90cff61c111e7d8cd15df311 /third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs | |
parent | 2eb1dc26e42ffbdc168f05ef744bd4b4f3e4c36f (diff) |
feat(third_party/bazel): Check in rules_haskell from Tweag r/17
Diffstat (limited to 'third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs')
-rw-r--r-- | third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs b/third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs new file mode 100644 index 000000000000..8b8ca837b890 --- /dev/null +++ b/third_party/bazel/rules_haskell/examples/vector/benchmarks/TestData/Graph.hs @@ -0,0 +1,45 @@ +module TestData.Graph ( randomGraph ) +where + +import System.Random.MWC +import qualified Data.Array.ST as STA +import qualified Data.Vector.Unboxed as V + +import Control.Monad.ST ( ST, runST ) + +randomGraph :: Int -> (Int, V.Vector Int, V.Vector Int) +randomGraph e + = runST ( + do + g <- create + arr <- STA.newArray (0,n-1) [] :: ST s (STA.STArray s Int [Int]) + addRandomEdges n g arr e + xs <- STA.getAssocs arr + let (as,bs) = unzip [(i,j) | (i,js) <- xs, j <- js ] + return (n, V.fromListN (length as) as, V.fromListN (length bs) bs) + ) + where + n = e `div` 10 + +addRandomEdges :: Int -> Gen s -> STA.STArray s Int [Int] -> Int -> ST s () +addRandomEdges n g arr = fill + where + fill 0 = return () + fill e + = do + m <- random_index + n <- random_index + let lo = min m n + hi = max m n + ns <- STA.readArray arr lo + if lo == hi || hi `elem` ns + then fill e + else do + STA.writeArray arr lo (hi:ns) + fill (e-1) + + random_index = do + x <- uniform g + let i = floor ((x::Double) * toEnum n) + if i == n then return 0 else return i + |