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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Moduleghc-internal-9.1003.0Haskell2010

GHC.Internal.Err

The GHC.Err module defines the code for the wired-in error functions, which have a special type in the compiler (with "open tyvars").

We cannot define these functions in a module where they might be used (e.g., GHC.Base), because the magical wired-in type will get confused with what the typechecker figures out.

  • 4 values
valueabsentErr :: a
#

Used for compiler-generated error message; encoding saves bytes of string junk.

valueundefined :: HasCallStack => a
#

A special case of error. It is expected that compilers will recognize this and insert error messages which are more appropriate to the context in which undefined appears.