Delay Errors Until Runtime

I would like to add an -XDelayErrors flag to GHC that

• changes most type errors into warnings
• replaces the faulty expressions with runtime exceptions

This would make haskell development a lot easier. For example, this makes it possible to load buggy code into ghci to be able to execute it and show inferred types.

$ cat hello.lhs 
> main = putStr "Hello World" >> putStr ','

$ inplace/bin/ghc-stage2 --make hello -XDelayErrors
[1 of 1] Compiling Main             ( hello.lhs, hello.o )
Linking hello ...

$ ./hello 
Hello World
hello: hello.lhs:1:41:
    Couldn't match expected type `GHC.Base.String'
                with actual type `GHC.Types.Char'
    In the first argument of `System.IO.putStr', namely ','
    In the second argument of `(GHC.Base.>>)', namely
      System.IO.putStr ','
    In the expression:
      System.IO.putStr "Hello World" GHC.Base.>> System.IO.putStr ','

Trac metadata

Trac field	Value
Version	7.3
Type	FeatureRequest
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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