Hugs (interpreter)

Hugs (Haskell User's Gofer System), also Hugs 98, is a bytecode interpreter for the functional programming language Haskell. Hugs is the successor to Gofer, and was originally derived from Gofer version 2.30b. Hugs and Gofer were originally developed by Mark P. Jones, now a professor at Portland State University.

Hugs comes with a simple graphics library. As a complete Haskell implementation that is portable and simple to install, Hugs is sometimes recommended for new Haskell users.

Hugs deviates from the Haskell 98 specification in several minor ways. For example, Hugs does not support mutually recursive modules. A list of differences exists.

The Hugs prompt is a Haskell read–eval–print loop (REPL). It accepts expressions for evaluation, but not module, type, or function definitions. Hugs can load Haskell modules at start-up.

Extensible records
An example of "Typed records with extensibility", a non standard feature unique to Hugs. Running with H98 compatibility turned off to activate language extensions: runhugs -98 test.hs