Safe Haskell is a GlasgowHaskellCompiler extension to the Haskell language which allows unsafe (or simply untrusted) code to be used safely from within a trusted codebase, by restricting which Haskell/GHC features the untrusted code may use.
Code may be marked as
Safe
does not use unsafe features.
Trusted
uses unsafe features but in such a way that the details are safely encapsulated and are not accessible via the public api.
Unsafe
uses unsafe features in a way which could taint any code which imports it.