Agda-2.5.2: A dependently typed functional programming language and proof assistant

Safe Haskell | None
Language | Haskell2010

Agda.TypeChecking.CompiledClause.Compile

Synopsis

- compileClauses :: Maybe (QName, Type) -> [Clause] -> TCM CompiledClauses
- data Cl = Cl {
  - clPats :: [Arg Pattern]
  - clBody :: Maybe Term
  }
- type Cls = [Cl]
- compileWithSplitTree :: (Term -> Term) -> SplitTree -> Cls -> CompiledClauses
- compile :: (Term -> Term) -> Cls -> CompiledClauses
- nextSplit :: Cls -> Maybe (Bool, Arg Int)
- properSplit :: Pattern' a -> Maybe Bool
- isVar :: Pattern' a -> Bool
- splitOn :: Bool -> Int -> Cls -> Case Cls
- splitC :: Int -> Cl -> Case Cl
- expandCatchAlls :: Bool -> Int -> Cls -> Cls
- ensureNPatterns :: Int -> [ArgInfo] -> Cl -> Cl
- substBody :: Subst t a => Int -> Int -> t -> a -> a

# Documentation

compileClauses #

Arguments

:: Maybe (QName, Type) | Translate record patterns and coverage check with given type?
-> [Clause] |
-> TCM CompiledClauses |

Process function clauses into case tree. This involves: 1. Coverage checking, generating a split tree. 2. Translation of lhs record patterns into rhs uses of projection. Update the split tree. 3. Generating a case tree from the split tree. Phases 1. and 2. are skipped if `Nothing`.

data Cl #

Stripped-down version of `Clause` used in clause compiler.

Constructors

Cl |
Fields clPats :: [Arg Pattern] Pattern variables are considered in left-to-right order. clBody :: Maybe Term

Instances

Show Cl # |
Methods showsPrec :: Int -> Cl -> ShowS # show :: Cl -> String # showList :: [Cl] -> ShowS #
Pretty Cl # |
Methods pretty :: Cl -> Doc # prettyPrec :: Int -> Cl -> Doc #

type Cls = [Cl] #

compileWithSplitTree :: (Term -> Term) -> SplitTree -> Cls -> CompiledClauses #

compile :: (Term -> Term) -> Cls -> CompiledClauses #

nextSplit :: Cls -> Maybe (Bool, Arg Int) #

Get the index of the next argument we need to split on. This the number of the first pattern that does a match in the first clause.

properSplit :: Pattern' a -> Maybe Bool #

Is is not a variable pattern? And if yes, is it a record pattern?

isVar :: Pattern' a -> Bool #

Is this a variable pattern?

Maintain invariant: `isVar = isNothing . properSplit`!

splitOn :: Bool -> Int -> Cls -> Case Cls #

`splitOn single n cs` will force expansion of catch-alls if `single`.

splitC :: Int -> Cl -> Case Cl #

expandCatchAlls :: Bool -> Int -> Cls -> Cls #

Expand catch-alls that appear before actual matches.

Example:

       true  y
       x     false
       false y

will expand the catch-all `x` to `false`.

Catch-alls need also to be expanded if they come before/after a record pattern, otherwise we get into trouble when we want to eliminate splits on records later.

Another example (see Issue 1650): `f (x, (y, z)) true = a f _ false = b` Split tree: `0 (first argument of f) - 1 (second component of the pair) - 3 (last argument of f) -- true -> a - false -> b` We would like to get the following case tree: `case 0 of _,_ -> case 1 of _,_ -> case 3 of true -> a; false -> b _ -> case 3 of true -> a; false -> b _ -> case 3 of true -> a; false -> b`

Example from issue #2168: `f x false = a f false = _ -> b f x true = c` case tree: `f x y = case y of true -> case x of true -> c false -> b false -> a`

ensureNPatterns :: Int -> [ArgInfo] -> Cl -> Cl #

Make sure (by eta-expansion) that clause has arity at least `n` where `n` is also the length of the provided list.

substBody :: Subst t a => Int -> Int -> t -> a -> a #