diff options
| author | Joachim Breitner <mail@joachim-breitner.de> | 2014-07-22 11:21:01 +0200 |
|---|---|---|
| committer | Joachim Breitner <mail@joachim-breitner.de> | 2014-07-22 11:21:01 +0200 |
| commit | b709f0a047dc036de15dc43d3b0ab88d3e32c5e6 (patch) | |
| tree | 96d91eb93731674656b40bd83e36867ddaf595d5 /libraries/base/GHC | |
| parent | 7aabfa6292c2469cf3250e006869273fb1b356ce (diff) | |
| download | haskell-b709f0a047dc036de15dc43d3b0ab88d3e32c5e6.tar.gz | |
Make last a good consumer
Summary:
Make last a good consumer simply by implementing it as foldl. This fixes Trac: #9339.
Thanks to David Feuer for bringing it up.
Test Plan: perf/should_run/T9339 + general validation
Reviewers: austin
Reviewed By: austin
Subscribers: phaskell, simonmar, relrod, carter
Differential Revision: https://phabricator.haskell.org/D86
Trac Issues: #9339
Diffstat (limited to 'libraries/base/GHC')
| -rw-r--r-- | libraries/base/GHC/List.lhs | 7 |
1 files changed, 2 insertions, 5 deletions
diff --git a/libraries/base/GHC/List.lhs b/libraries/base/GHC/List.lhs index e004ded1e8..9b6cc2eb19 100644 --- a/libraries/base/GHC/List.lhs +++ b/libraries/base/GHC/List.lhs @@ -83,11 +83,8 @@ last [x] = x last (_:xs) = last xs last [] = errorEmptyList "last" #else --- eliminate repeated cases -last [] = errorEmptyList "last" -last (x:xs) = last' x xs - where last' y [] = y - last' _ (y:ys) = last' y ys +-- use foldl to allow fusion +last = foldl (\_ x -> x) (errorEmptyList "last") #endif -- | Return all the elements of a list except the last one. |