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.

1. (implicitly) Import GHC.Stack for all modules.
2. 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 _ = f5 0 0 -- HsFunTy f5 :: Int -> 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 fError -- HsTyVar fError :: Int fError = error "fError" 

This example get error:

$ cabal new-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 new-run example: fError CallStack (from HasCallStack): error, called at example/Main.hs:41:10 in main:Main 

Hmm, it is not useful. But, you will to be happy when enable this plugin.

 ghc-options: -fplugin=StackTrace.Plugin 

$ cabal new-run ... example: fError CallStack (from HasCallStack): error, called at example/Main.hs:40:10 in main:Main fError, called at example/Main.hs:36:11 in main:Main f8, called at example/Main.hs:32:16 in main:Main f7, called at example/Main.hs:28:11 in main:Main f6, called at example/Main.hs:24:15 in main:Main f5, called at example/Main.hs:20:8 in main:Main f4, called at example/Main.hs:16:6 in main:Main f3, called at example/Main.hs:12:6 in main:Main f2, called at example/Main.hs:9:6 in main:Main f1, called at example/Main.hs:6:14 in main:Main main, called at example/Main.hs:6:1 in main:Main 

Great!!!