Clash.Core.EqSolver

Documentation

data TypeEqSolution

Data type that indicates what kind of solution (if any) was found

Constructors

Solution (TyVar, Type)

Solution was found. Variable equals some integer.

AbsurdSolution

A solution was found, but it involved negative naturals.

NoSolution

Given type wasn't an equation, or it was unsolvable.

Instances

Eq TypeEqSolution

Defined in Clash.Core.EqSolver

Methods

(==) :: TypeEqSolution -> TypeEqSolution -> Bool

(/=) :: TypeEqSolution -> TypeEqSolution -> Bool

Show TypeEqSolution

Defined in Clash.Core.EqSolver

Methods

showsPrec :: Int -> TypeEqSolution -> ShowS

show :: TypeEqSolution -> String

showList :: [TypeEqSolution] -> ShowS

catSolutions :: [TypeEqSolution] -> [(TyVar, Type)]

solveNonAbsurds :: TyConMap -> VarSet -> [(Type, Type)] -> [(TyVar, Type)]

Solve given equations and return all non-absurd solutions

solveEq :: TyConMap -> VarSet -> (Type, Type) -> [TypeEqSolution]

Solve simple equalities such as:

• a ~ 3
• 3 ~ a
• SomeType a b ~ SomeType 3 5
• SomeType 3 5 ~ SomeType a b
• SomeType a 5 ~ SomeType 3 b

solveAdd :: VarSet -> (Type, Type) -> TypeEqSolution

Solve equations supported by normalizeAdd. See documentation of TypeEqSolution to understand the return value.

normalizeAdd :: (Type, Type) -> Maybe (Integer, Integer, Type)

Given the left and right side of an equation, normalize it such that equations of the following forms:

• 5 ~ n + 2
• 5 ~ 2 + n
• n + 2 ~ 5
• 2 + n ~ 5

are returned as (5, 2, n)

isAbsurdPat :: TyConMap -> Pat -> Bool

Tests for nonsencical patterns due to types being "absurd". See isAbsurdEq for more info.

isAbsurdEq

Arguments

:: TyConMap

-> VarSet

existential tvs

-> (Type, Type)

-> Bool

Determines if an "equation" obtained through patEqs or typeEq is absurd. That is, it tests if two types that are definitely not equal are asserted to be equal OR if the computation of the types yield some absurd (intermediate) result such as -1.

patEqs :: TyConMap -> Pat -> [(Type, Type)]

Get constraint equations

typeEq :: TyConMap -> Type -> Maybe (Type, Type)

If type is an equation, return LHS and RHS.