Agda.Compiler.Epic.Erasure

Some arguments to functions (types in particular) will not be used in the body. Wouldn't it be useful if these wasn't passed around at all? Fear not, we here perform some analysis and try to remove as many of these occurences as possible.

We employ the worker/wrapper transform, so if f x1 .. xn = e and we notice that some is not needed we create: f' xj .. xk = e [xi := unit] and f x1 .. xn = f' xj .. xk. i.e we erase them in f' and replace by unit, and the original f function calls the new f'. The idea is that f should be inlined and then peace on earth.

Documentation

isIrr :: Relevance -> Bool

isRel :: Relevance -> Bool

(||-) :: Relevance -> Relevance -> Relevance infixr 2

Relevance "or"

(&&-) :: Relevance -> Relevance -> Relevance infixr 3

Relevance "and"

data ErasureState

Constructors

ErasureState

Fields

• relevancies :: Map Var [Relevance]
• funs :: Map Var Fun

type Erasure = StateT ErasureState

erasure :: [Fun] -> Compile TCM [Fun]

Try to find as many unused variables as possible

removeUnused :: Map Var [Relevance] -> Expr -> Expr

initiate :: Fun -> Erasure (Compile TCM) ()

Initiate a function's relevancies

initialRels :: Type -> Relevance -> [Relevance]

ignoreForced :: Relevance -> Bool

relevant :: Monad m => Var -> Expr -> Erasure m Relevance

Calculate if a variable is relevant in an expression

step :: Integer -> Erasure (Compile TCM) (Map Var [Relevance])

Try to find a fixpoint for all the functions relevance.

diff :: Eq a => Map k a -> Map k a -> [(k, (a, a))]