Language.Haskell.FreeTheorems.Parser.Hsx

Documentation

parse :: String -> Parsed [Declaration]

Parses a string to a list of declarations. The string should contain a Haskell module.

This function is based on the extended Haskell parser of the 'haskell-src-exts' package.

The declarations returned by parse include only type, data, newtype, class and type signature declarations. All other declarations and syntactical elements in the input are ignored.

Furthermore, the following restrictions apply:

• Multi-parameter type classes are not allowed and therefore ignored. When declaring a type class, the argument to the type class name must be a single type variable.
• Only type variables can be constrained by type classes. That means, for example, the type Eq [a] => [a] is not accepted.
• A type variable must not be applied to any type. That means, for example, that the type m a is not accepted.
• Contexts and deriving parts in data and newtype declarations are ignored.
• The module names are ignored. If any identifier was given qualified, the module part of a qualified name is ignored.
• Special Haskell constructors (unit, list function) are not allowed as identifiers.
• Further extensions over Haskell98 allowed by the underlying parser are also forbidden, namely generalised algebraic data types and unboxed tuples.

If a parser error occurs, as suitable error message is returned in the second component of the returned tuple and the first component will be the empty list. However, if parsing was successful, but the parsed structures could not be completely transformed into Declarations, suitable transformation error messages are returned in the second component while the first components contains all declarations which could be transformed successfully.