quox/lib/Quox/Syntax/DimEq.idr
2023-11-03 18:05:54 +01:00

295 lines
8 KiB
Idris

module Quox.Syntax.DimEq
import public Quox.Var
import public Quox.Syntax.Dim
import public Quox.Syntax.Subst
import public Quox.Context
import Quox.Pretty
import Quox.Name
import Quox.FreeVars
import Data.Maybe
import Data.Nat
import Data.DPair
import Data.Fun.Graph
import Decidable.Decidable
import Decidable.Equality
import Derive.Prelude
%language ElabReflection
%default total
public export
DimEq' : Nat -> Type
DimEq' = Context (Maybe . Dim)
public export
data DimEq : Nat -> Type where
ZeroIsOne : DimEq d
C : (eqs : DimEq' d) -> DimEq d
%name DimEq eqs
%runElab deriveIndexed "DimEq" [Eq, Ord, Show]
public export
consistent : DimEq d -> Bool
consistent ZeroIsOne = False
consistent (C eqs) = True
public export
data IfConsistent : DimEq d -> Type -> Type where
Nothing : IfConsistent ZeroIsOne a
Just : a -> IfConsistent (C eqs) a
export
Functor (IfConsistent eqs) where
map f Nothing = Nothing
map f (Just x) = Just (f x)
export
Foldable (IfConsistent eqs) where
foldr f z Nothing = z
foldr f z (Just x) = f x z
export
Traversable (IfConsistent eqs) where
traverse f Nothing = pure Nothing
traverse f (Just x) = Just <$> f x
public export
ifConsistent : Applicative f => (eqs : DimEq d) -> f a -> f (IfConsistent eqs a)
ifConsistent ZeroIsOne act = pure Nothing
ifConsistent (C _) act = Just <$> act
public export
toMaybe : IfConsistent eqs a -> Maybe a
toMaybe Nothing = Nothing
toMaybe (Just x) = Just x
export
fromGround' : Context' DimConst d -> DimEq' d
fromGround' [<] = [<]
fromGround' (ctx :< e) = fromGround' ctx :< Just (K e noLoc)
export
fromGround : Context' DimConst d -> DimEq d
fromGround = C . fromGround'
public export %inline
zeroEq : DimEq 0
zeroEq = C [<]
public export %inline
new' : {d : Nat} -> DimEq' d
new' {d = 0} = [<]
new' {d = S d} = new' :< Nothing
public export %inline
new : {d : Nat} -> DimEq d
new = C new'
public export %inline
get' : DimEq' d -> Var d -> Maybe (Dim d)
get' = getWith $ \p, by => map (// by) p
public export %inline
getVar : DimEq' d -> Var d -> Loc -> Dim d
getVar eqs i loc = fromMaybe (B i loc) $ get' eqs i
public export %inline
getShift' : Shift len out -> DimEq' len -> Var len -> Maybe (Dim out)
getShift' = getShiftWith $ \p, by => map (// by) p
public export %inline
get : DimEq' d -> Dim d -> Dim d
get _ (K e loc) = K e loc
get eqs (B i loc) = getVar eqs i loc
public export %inline
equal : DimEq d -> (p, q : Dim d) -> Bool
equal ZeroIsOne p q = True
equal (C eqs) p q = get eqs p == get eqs q
infixl 7 :<?
export %inline
(:<?) : DimEq d -> Maybe (Dim d) -> DimEq (S d)
ZeroIsOne :<? d = ZeroIsOne
C eqs :<? d = C $ eqs :< map (get eqs) d
private %inline
ifVar : Var d -> Dim d -> Maybe (Dim d) -> Maybe (Dim d)
ifVar i p = map $ \q => if q == B i noLoc then p else q
-- (using decEq instead of (==) because of the proofs below)
private %inline
checkConst : (e, f : DimConst) -> (eqs : Lazy (DimEq' d)) -> DimEq d
checkConst e f eqs = if isYes $ e `decEq` f then C eqs else ZeroIsOne
export
setConst : Var d -> DimConst -> Loc -> DimEq' d -> DimEq d
setConst VZ e loc (eqs :< Nothing) =
C $ eqs :< Just (K e loc)
setConst VZ e _ (eqs :< Just (K f loc)) =
checkConst e f $ eqs :< Just (K f loc)
setConst VZ e loc (eqs :< Just (B i _)) =
setConst i e loc eqs :<? Just (K e loc)
setConst (VS i) e loc (eqs :< p) =
setConst i e loc eqs :<? ifVar i (K e loc) p
mutual
private
setVar' : (i, j : Var d) -> (0 _ : i `LT` j) -> Loc -> DimEq' d -> DimEq d
setVar' VZ (VS i) LTZ loc (eqs :< Nothing) =
C eqs :<? Just (B i loc)
setVar' VZ (VS i) LTZ loc (eqs :< Just (K e eloc)) =
setConst i e loc eqs :<? Just (K e eloc)
setVar' VZ (VS i) LTZ loc (eqs :< Just (B j jloc)) =
setVar i j loc jloc eqs :<? Just (if j > i then B j jloc else B i loc)
setVar' (VS i) (VS j) (LTS lt) loc (eqs :< p) =
setVar' i j lt loc eqs :<? ifVar i (B j loc) p
export %inline
setVar : (i, j : Var d) -> Loc -> Loc -> DimEq' d -> DimEq d
setVar i j li lj eqs with (compareP i j) | (compare i.nat j.nat)
setVar i j li lj eqs | IsLT lt | LT = setVar' i j lt lj eqs
setVar i i li lj eqs | IsEQ | EQ = C eqs
setVar i j li lj eqs | IsGT gt | GT = setVar' j i gt li eqs
export %inline
set : (p, q : Dim d) -> DimEq d -> DimEq d
set _ _ ZeroIsOne = ZeroIsOne
set (K e eloc) (K f floc) (C eqs) = checkConst e f eqs
set (K e eloc) (B i iloc) (C eqs) = setConst i e eloc eqs
set (B i iloc) (K e eloc) (C eqs) = setConst i e eloc eqs
set (B i iloc) (B j jloc) (C eqs) = setVar i j iloc jloc eqs
public export %inline
Split : Nat -> Type
Split d = (DimEq' d, DSubst (S d) d)
export %inline
split1 : DimConst -> Loc -> DimEq' (S d) -> Maybe (Split d)
split1 e loc eqs = case setConst VZ e loc eqs of
ZeroIsOne => Nothing
C (eqs :< _) => Just (eqs, K e loc ::: id)
export %inline
split1' : DimConst -> Loc -> DimEq' (S d) -> List (Split d)
split1' e loc eqs = toList $ split1 e loc eqs
export %inline
split : Loc -> DimEq' (S d) -> Bool -> List (Split d)
split loc eqs False = split1' Zero loc eqs
split loc eqs True = split1' Zero loc eqs <+> split1' One loc eqs
export
splits' : Loc -> DimEq' d -> FreeVars d -> List (DSubst d 0)
splits' _ [<] _ = [id]
splits' loc eqs@(_ :< _) us = do
let (us, u) = uncons us
(eqs', th) <- split loc eqs u
ph <- splits' loc eqs' us
pure $ th . ph
||| the Loc is put into each of the DimConsts
export %inline
splits : Loc -> DimEq d -> FreeVars d -> List (DSubst d 0)
splits _ ZeroIsOne _ = []
splits loc (C eqs) fvs = splits' loc eqs fvs
private
0 newGetShift : (d : Nat) -> (i : Var d) -> (by : Shift d d') ->
getShift' by (new' {d}) i = Nothing
newGetShift (S d) VZ by = Refl
newGetShift (S d) (VS i) by = newGetShift d i (ssDown by)
export
0 newGet' : (d : Nat) -> (i : Var d) -> get' (new' {d}) i = Nothing
newGet' d i = newGetShift d i SZ
export
0 newGet : (d : Nat) -> (p : Dim d) -> get (new' {d}) p = p
newGet d (K e _) = Refl
newGet d (B i _) = rewrite newGet' d i in Refl
export
0 setSelf : (p : Dim d) -> (eqs : DimEq d) -> set p p eqs = eqs
setSelf p ZeroIsOne = Refl
setSelf (K Zero _) (C eqs) = Refl
setSelf (K One _) (C eqs) = Refl
setSelf (B i _) (C eqs) with (compareP i i) | (compare i.nat i.nat)
_ | IsLT lt | LT = absurd lt
_ | IsEQ | EQ = Refl
_ | IsGT gt | GT = absurd gt
private %inline
dimEqPrec : BContext d -> Maybe (DimEq' d) -> PPrec
dimEqPrec vars eqs =
if length vars <= 1 && maybe True null eqs then Arg else Outer
private
prettyDVars' : {opts : _} -> BContext d -> Eff Pretty (SnocList (Doc opts))
prettyDVars' = traverse prettyDBind . toSnocList'
export
prettyDVars : {opts : _} -> BContext d -> Eff Pretty (Doc opts)
prettyDVars vars =
parensIfM (dimEqPrec vars Nothing) $
fillSeparateTight !commaD $ !(prettyDVars' vars)
private
prettyCst : {opts : _} -> BContext d -> Dim d -> Dim d -> Eff Pretty (Doc opts)
prettyCst dnames p q =
hsep <$> sequence [prettyDim dnames p, cstD, prettyDim dnames q]
private
prettyCsts : {opts : _} -> BContext d -> DimEq' d ->
Eff Pretty (SnocList (Doc opts))
prettyCsts [<] [<] = pure [<]
prettyCsts dnames (eqs :< Nothing) = prettyCsts (tail dnames) eqs
prettyCsts dnames (eqs :< Just q) =
[|prettyCsts (tail dnames) eqs :< prettyCst dnames (BV 0 noLoc) (weakD 1 q)|]
export
prettyDimEq' : {opts : _} -> BContext d -> DimEq' d -> Eff Pretty (Doc opts)
prettyDimEq' vars eqs = do
vars' <- prettyDVars' vars
eqs' <- prettyCsts vars eqs
parensIfM (dimEqPrec vars (Just eqs)) $
fillSeparateTight !commaD $ vars' ++ eqs'
export
prettyDimEq : {opts : _} -> BContext d -> DimEq d -> Eff Pretty (Doc opts)
prettyDimEq dnames ZeroIsOne = do
vars <- prettyDVars' dnames
cst <- prettyCst [<] (K Zero noLoc) (K One noLoc)
pure $ separateTight !commaD $ vars :< cst
prettyDimEq dnames (C eqs) = prettyDimEq' dnames eqs
public export
wf' : DimEq' d -> Bool
wf' [<] = True
wf' (eqs :< Nothing) = wf' eqs
wf' (eqs :< Just (K e _)) = wf' eqs
wf' (eqs :< Just (B i _)) = isNothing (get' eqs i) && wf' eqs
public export
wf : DimEq d -> Bool
wf ZeroIsOne = True
wf (C eqs) = wf' eqs