haskell-stack-trace-plugin
This plugin allow implicitly add HasCallStack class to every top-level function for all module. Hence, we can to get completely continuous call stack.
- (implicitly) Import GHC.Stack for all modules.
- Add HasCallStack constraint for all top-level functions.
Requirement: (8.6 <= on GHC)
Synopsis
module Main where
import Data.Maybe (fromJust)
main :: IO ()
main = print f1
f1 :: Int
f1 = f2
f2 :: Int
f2 = f3
-- HsQualTy
f3 :: HasCallStack => Int
f3 = f4 0
-- HsQualTy
f4 :: Show a => a -> Int
f4 n = f5 (show n) 0
-- HsFunTy
f5 :: String -> Int -> Int
f5 _ _ = head f6
-- HsListTy
f6 :: [Int]
f6 = [fst f7]
-- HsTupleTy
f7 :: (Int, Int)
f7 = (fromJust f8, fromJust f8)
-- HsAppTy
f8 :: Maybe Int
f8 = Just f9
f9 :: Int
f9 = f10
where
f10 :: Int
f10 = fError
-- HsTyVar
fError :: Int
fError = error "fError"This example get error:
$ cabal build
example/Main.hs:15:7: error:
Not in scope: type constructor or class ‘HasCallStack’
|
15 | f3 :: HasCallStack => Int
| ^^^^^^^^^^^^Yes, add import GHC.Stack to above example.
Fix and rebuild!
$ cabal run example -v0
example: fError
CallStack (from HasCallStack):
error, called at example/Main.hs:47:10 in main:MainHmm, it is not useful. But, you will to be happy when enable this plugin.
ghc-options:
-fplugin=StackTrace.Plugin$ cabal run example -v0
example: fError
CallStack (from HasCallStack):
error, called at example/Main.hs:47:10 in main:Main
fError, called at example/Main.hs:43:11 in main:Main
f10, called at example/Main.hs:40:6 in main:Main
f9, called at example/Main.hs:37:11 in main:Main
f8, called at example/Main.hs:33:16 in main:Main
f7, called at example/Main.hs:29:11 in main:Main
f6, called at example/Main.hs:25:15 in main:Main
f5, called at example/Main.hs:21:8 in main:Main
f4, called at example/Main.hs:17:6 in main:Main
f3, called at example/Main.hs:13:6 in main:Main
f2, called at example/Main.hs:10:6 in main:Main
f1, called at example/Main.hs:7:14 in main:Main
main, called at example/Main.hs:7:1 in main:MainGreat!!!
