add context stuff

This commit is contained in:
rhiannon morris 2021-09-09 23:56:10 +02:00
parent 3f11530336
commit e0bf8fa795
4 changed files with 233 additions and 0 deletions

185
src/Quox/Context.idr Normal file
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@ -0,0 +1,185 @@
module Quox.Context
import Quox.Syntax.Shift
import Quox.Pretty
import Data.DPair
import Data.Nat
import Data.SnocList
import Control.Monad.Identity
%default total
infixl 5 :<
||| a sequence of bindings under an existing context. each successive element
||| has one more bound variable, which correspond to all previous elements
||| as well as the global context.
public export
data Telescope : (tm : Nat -> Type) -> (from, to : Nat) -> Type where
Lin : Telescope tm from from
(:<) : Telescope tm from to -> tm to -> Telescope tm from (S to)
%name Telescope tel
||| a global context is actually just a telescope over no existing bindings
public export
Context : (tm : Nat -> Type) -> (len : Nat) -> Type
Context tm len = Telescope tm 0 len
export
toSnocList : Telescope tm _ _ -> SnocList (Exists tm)
toSnocList [<] = [<]
toSnocList (tel :< t) = toSnocList tel :< Evidence _ t
private
toList' : Telescope tm _ _ -> List (Exists tm) -> List (Exists tm)
toList' [<] acc = acc
toList' (tel :< t) acc = toList' tel (Evidence _ t :: acc)
export %inline
toList : Telescope tm _ _ -> List (Exists tm)
toList tel = toList' tel []
infixl 9 .
public export
(.) : Telescope tm from mid -> Telescope tm mid to -> Telescope tm from to
tel1 . [<] = tel1
tel1 . (tel2 :< s) = (tel1 . tel2) :< s
export
getWith : CanShift tm => Context tm len -> Var len -> Shift len out -> tm out
getWith (ctx :< t) VZ th = t // drop1 th
getWith (ctx :< t) (VS i) th = getWith ctx i (drop1 th)
infixl 8 !!
export %inline
(!!) : CanShift tm => Context tm len -> Var len -> tm len
ctx !! i = getWith ctx i SZ
||| a triangle of bindings. each type binding in a context counts the ues of
||| others in its type, and all of these together form a triangle.
public export
Triangle : (tm : Nat -> Type) -> (len : Nat) -> Type
Triangle = Context . Context
export
0 telescopeLTE : Telescope _ from to -> from `LTE` to
telescopeLTE [<] = reflexive {rel=LTE}
telescopeLTE (tel :< _) = lteSuccRight $ telescopeLTE tel
export
(from `GT` to) => Uninhabited (Telescope _ from to) where
uninhabited tel = void $ LTEImpliesNotGT (telescopeLTE tel) %search
export %hint
0 succGT : S n `GT` n
succGT = LTESucc $ reflexive {rel=LTE}
export %inline
absurd0 : (0 _ : Uninhabited a) => (0 _ : a) -> x
absurd0 x = void $ absurd x
parameters {auto _ : Applicative f}
export
traverse : (forall n. tm1 n -> f (tm2 n)) ->
Telescope tm1 from to -> f (Telescope tm2 from to)
traverse f [<] = pure [<]
traverse f (tel :< x) = [|traverse f tel :< f x|]
infixl 3 `app`
||| like `(<*>)` but with effects
export
app : Telescope (\n => tm1 n -> f (tm2 n)) from to ->
Telescope tm1 from to -> f (Telescope tm2 from to)
app [<] [<] = pure [<]
app (ftel :< f) (xtel :< x) = [|app ftel xtel :< f x|]
app [<] (xtel :< _) = absurd0 xtel
app (ftel :< _) [<] = absurd0 ftel
export %inline
sequence : Telescope (f . tm) from to -> f (Telescope tm from to)
sequence = traverse id
export %inline
map : (forall n. tm1 n -> tm2 n) ->
Telescope tm1 from to -> Telescope tm2 from to
map f = runIdentity . traverse (pure . f)
infixr 4 <$>
export %inline
(<$>) : (forall n. tm1 n -> tm2 n) ->
Telescope tm1 from to -> Telescope tm2 from to
(<$>) = map
infixl 3 <*>
export %inline
(<*>) : Telescope (\n => tm1 n -> tm2 n) from to ->
Telescope tm1 from to -> Telescope tm2 from to
ftel <*> xtel = runIdentity $ (pure .) <$> ftel `app` xtel
-- ...but can't write pure without `from,to` being relevant,
-- so no idiom brackets ☹
export %inline
zipWith : (forall n. tm1 n -> tm2 n -> tm3 n) ->
Telescope tm1 from to -> Telescope tm2 from to ->
Telescope tm3 from to
zipWith f tel1 tel2 = f <$> tel1 <*> tel2
export %inline
zipWith3 : (forall n. tm1 n -> tm2 n -> tm3 n -> tm4 n) ->
Telescope tm1 from to ->
Telescope tm2 from to ->
Telescope tm3 from to ->
Telescope tm4 from to
zipWith3 f tel1 tel2 tel3 = f <$> tel1 <*> tel2 <*> tel3
export
lengthPrf : Telescope _ from to -> Subset Nat (\len => len + from = to)
lengthPrf [<] = Element 0 Refl
lengthPrf (tel :< _) =
let len = lengthPrf tel in Element (S len.fst) (cong S len.snd)
public export %inline
length : Telescope {} -> Nat
length = fst . lengthPrf
parameters {0 acc : Nat -> Type}
export
foldl : (forall m, n. acc m -> tm n -> acc (S m)) ->
acc 0 -> (tel : Telescope tm from to) -> acc (length tel)
foldl f z [<] = z
foldl f z (tel :< t) = f (foldl f z tel) t
parameters {auto _ : Monoid a}
export %inline
foldMap : (forall n. tm n -> a) -> Telescope tm from to -> a
foldMap f = foldl (\acc, tm => acc <+> f tm) neutral
export %inline
fold : Telescope (\x => a) from to -> a
fold = foldMap id
||| like `fold` but calculate the elements only when actually appending
export %inline
foldLazy : Telescope (\x => Lazy a) from to -> a
foldLazy = foldMap force
export
(forall n. Eq (tm n)) => Eq (Telescope tm from to) where
(==) = fold @{All} .: zipWith (==)
export
(forall n. Ord (tm n)) => Ord (Telescope tm from to) where
compare = foldLazy .: zipWith (delay .: compare)
export
(forall n. PrettyHL (tm n)) => PrettyHL (Telescope tm from to) where
prettyM tel = separate (hl Delim ";") <$> traverse prettyM (toList tel)

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@ -97,6 +97,25 @@ parensIf True = parens
parensIf False = id
export
separate' : Doc a -> List (Doc a) -> List (Doc a)
separate' s [] = []
separate' s [x] = [x]
separate' s (x :: xs) = x <+> s :: separate' s xs
export %inline
separate : Doc a -> List (Doc a) -> Doc a
separate s = sep . separate' s
export %inline
hseparate : Doc a -> List (Doc a) -> Doc a
hseparate s = hsep . separate' s
export %inline
vseparate : Doc a -> List (Doc a) -> Doc a
vseparate s = vsep . separate' s
public export
record PrettyEnv where
constructor MakePrettyEnv

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@ -174,6 +174,30 @@ prettyShift bnd by =
export PrettyHL (Shift from to) where prettyM = prettyShift TVar
||| Drops the innermost variable from the input scope.
public export
drop1 : Shift (S from) to -> Shift from to
drop1 SZ = SS SZ
drop1 (SS by) = SS (drop1 by)
private
drop1ViaNat : Shift (S from) to -> Shift from to
drop1ViaNat by =
rewrite shiftDiff by in
rewrite sym $ plusSuccRightSucc by.nat from in
fromNat (S by.nat)
private
0 drop1ViaNatCorrect : (by : Shift (S from) to) -> drop1ViaNat by = drop1 by
drop1ViaNatCorrect SZ = Refl
drop1ViaNatCorrect (SS by) =
rewrite plusSuccRightSucc by.nat from in
rewrite sym $ shiftDiff by in
cong SS $ drop1ViaNatCorrect by
%transform "Shift.drop1" drop1 by = drop1ViaNat by
infixl 8 //
public export
interface CanShift f where

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@ -84,6 +84,11 @@ public export %inline
push : CanSubst1 f => Subst f from to -> Subst f (S from) (S to)
push th = fromVar VZ ::: (th . shift 1)
public export
drop1 : Subst f (S from) to -> Subst f from to
drop1 (Shift by) = Shift $ drop1 by
drop1 (t ::: th) = th
||| `prettySubst pr bnd op cl unicode th` pretty-prints the substitution `th`,
||| with the following arguments: