140 lines
3.1 KiB
Idris
140 lines
3.1 KiB
Idris
module Quox.Syntax.Dim
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import Quox.Loc
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import Quox.Name
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import Quox.Syntax.Var
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import Quox.Syntax.Subst
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import Quox.Pretty
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import Quox.Context
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import Decidable.Equality
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import Control.Function
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import Derive.Prelude
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%default total
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%language ElabReflection
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public export
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data DimConst = Zero | One
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%name DimConst e
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%runElab derive "DimConst" [Eq, Ord, Show]
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||| `ends l r e` returns `l` if `e` is `Zero`, or `r` if it is `One`.
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public export
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ends : Lazy a -> Lazy a -> DimConst -> a
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ends l r Zero = l
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ends l r One = r
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export Uninhabited (Zero = One) where uninhabited _ impossible
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export Uninhabited (One = Zero) where uninhabited _ impossible
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public export
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DecEq DimConst where
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decEq Zero Zero = Yes Refl
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decEq Zero One = No absurd
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decEq One Zero = No absurd
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decEq One One = Yes Refl
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public export
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data Dim : Nat -> Type where
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K : DimConst -> Loc -> Dim d
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B : Var d -> Loc -> Dim d
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%name Dim.Dim p, q
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%runElab deriveIndexed "Dim" [Eq, Ord, Show]
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||| `endsOr l r x p` returns `ends l r ε` if `p` is a constant ε, and
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||| `x` otherwise.
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public export
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endsOr : Lazy a -> Lazy a -> Lazy a -> Dim n -> a
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endsOr l r x (K e _) = ends l r e
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endsOr l r x (B _ _) = x
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export
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Located (Dim d) where
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(K _ loc).loc = loc
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(B _ loc).loc = loc
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export
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Relocatable (Dim d) where
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setLoc loc (K e _) = K e loc
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setLoc loc (B i _) = B i loc
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export
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prettyDimConst : {opts : _} -> DimConst -> Eff Pretty (Doc opts)
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prettyDimConst = hl Dim . text . ends "0" "1"
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export
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prettyDim : {opts : _} -> BContext d -> Dim d -> Eff Pretty (Doc opts)
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prettyDim names (K e _) = prettyDimConst e
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prettyDim names (B i _) = prettyDBind $ names !!! i
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public export %inline
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toConst : Dim 0 -> DimConst
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toConst (K e _) = e
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public export
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DSubst : Nat -> Nat -> Type
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DSubst = Subst Dim
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public export FromVar Dim where fromVarLoc = B
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export
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CanShift Dim where
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K e loc // _ = K e loc
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B i loc // by = B (i // by) loc
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export
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CanSubstSelf Dim where
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K e loc // _ = K e loc
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B i loc // th = getLoc th i loc
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export Uninhabited (B i loc1 = K e loc2) where uninhabited _ impossible
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export Uninhabited (K e loc1 = B i loc2) where uninhabited _ impossible
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public export
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data Eqv : Dim d1 -> Dim d2 -> Type where
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EK : K e _ `Eqv` K e _
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EB : i `Eqv` j -> B i _ `Eqv` B j _
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export Uninhabited (K e l1 `Eqv` B i l2) where uninhabited _ impossible
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export Uninhabited (B i l1 `Eqv` K e l2) where uninhabited _ impossible
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export
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injectiveB : B i loc1 `Eqv` B j loc2 -> i `Eqv` j
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injectiveB (EB e) = e
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export
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injectiveK : K e loc1 `Eqv` K f loc2 -> e = f
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injectiveK EK = Refl
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public export
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decEqv : Dec2 Dim.Eqv
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decEqv (K e _) (K f _) = case decEq e f of
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Yes Refl => Yes EK
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No n => No $ n . injectiveK
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decEqv (B i _) (B j _) = case decEqv i j of
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Yes y => Yes $ EB y
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No n => No $ \(EB y) => n y
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decEqv (B _ _) (K _ _) = No absurd
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decEqv (K _ _) (B _ _) = No absurd
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||| abbreviation for a bound variable like `BV 4` instead of
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||| `B (VS (VS (VS (VS VZ))))`
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public export %inline
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BV : (i : Nat) -> (0 _ : LT i d) => (loc : Loc) -> Dim d
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BV i loc = B (V i) loc
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export
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weakD : (by : Nat) -> Dim d -> Dim (by + d)
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weakD by p = p // shift by
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