Documentation

Gets the unapplied top-level name from a type application.

Fetches the Name of a TyVarBndr.

Creates a TyVarBndr for a plain variable without a kind annotation.

Substitutes a Type for all occurrences of the given Name.

Makes variable substitutions from the given table.

Splits a function type into a list of bound type vars, context, parameter types, and return value type.

Gets all free type variable Names in the given Type.

Culls the given binders and constraints to choose only those that apply to free variables in the given type.

Produces a CxtQ that gives all given variable Names all of the given class Types.

Attempts to unify the given types by constructing a table of substitutions for the variables of the left type that obtain the right one.

Removes all module names from Names in the given value, so that it will pretty-print more cleanly.

Determines if this is a polytype, including top-level quantification.

Determines if there is a polytype nested anywhere in the given type. Top-level quantification doesn't count.

Attempts to produce sufficient constraints for the given Type to be an instance of the given class Name.

Attempts to produce sufficient constraints for the given Type to be a satisfied constraint. The type should be a class applied to its type parameters.

Unlike simplifyContext, this function always resolves the top-level constraint, and returns Nothing if it cannot do so.

Simplifies a context with complex types (requiring FlexibleContexts) to try to obtain one with all constraints applied to variables.

Should return Nothing if and only if the simplified contraint is unsatisfiable, which is the case if and only if it contains a component with no type variables.

Remove instance context from a method.

Some GHC versions report class members including the instance context (for example, show :: Show a => a -> String, instead of show :: a -> String). This looks for the instance context, and substitutes if needed to eliminate it.