split OPE stuff into modules

This commit is contained in:
rhiannon morris 2022-11-06 12:39:33 +01:00
parent 4b64399891
commit 5c3f2510fe
9 changed files with 446 additions and 366 deletions

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||| a smaller scope and part of a larger one. ||| a smaller scope and part of a larger one.
module Quox.OPE module Quox.OPE
import Quox.NatExtra import public Quox.OPE.Basics
import public Data.DPair import public Quox.OPE.Length
import public Data.SnocList import public Quox.OPE.Sub
import public Data.SnocList.Elem import public Quox.OPE.Split
import public Quox.OPE.Comp
%default total import public Quox.OPE.Cover
LTE_n = Nat.LTE
%hide Nat.LTE
public export
Scope : Type -> Type
Scope = SnocList
public export
data LTE : Scope a -> Scope a -> Type where
End : [<] `LTE` [<]
Keep : xs `LTE` ys -> xs :< z `LTE` ys :< z
Drop : xs `LTE` ys -> xs `LTE` ys :< z
%name LTE p, q
-- [todo] bitmask representation???
export
dropLast : (xs :< x) `LTE` ys -> xs `LTE` ys
dropLast (Keep p) = Drop p
dropLast (Drop p) = Drop $ dropLast p
export
Uninhabited (xs :< x `LTE` [<]) where uninhabited _ impossible
export
Uninhabited (xs :< x `LTE` xs) where
uninhabited (Keep p) = uninhabited p
uninhabited (Drop p) = uninhabited $ dropLast p
export
0 lteLen : xs `LTE` ys -> length xs `LTE_n` length ys
lteLen End = LTEZero
lteLen (Keep p) = LTESucc $ lteLen p
lteLen (Drop p) = lteSuccRight $ lteLen p
export
0 lteNilRight : xs `LTE` [<] -> xs = [<]
lteNilRight End = Refl
export
0 lteNilLeftDrop : (p : [<] `LTE` (xs :< x)) -> Exists (\q => p = Drop q)
lteNilLeftDrop (Drop q) = Evidence q Refl
export
0 lteNil2End : (p : [<] `LTE` [<]) -> p = End
lteNil2End End = Refl
public export
data Length : Scope a -> Type where
Z : Length [<]
S : (s : Length xs) -> Length (xs :< x)
%name Length s
%builtin Natural Length
namespace Length
public export
(.nat) : Length xs -> Nat
(Z).nat = Z
(S s).nat = S s.nat
%transform "Length.nat" Length.(.nat) xs = believe_me xs
export
0 lengthOk : (s : Length xs) -> s.nat = length xs
lengthOk Z = Refl
lengthOk (S s) = cong S $ lengthOk s
export %hint
lengthLeft : xs `LTE` ys -> Length xs
lengthLeft End = Z
lengthLeft (Keep p) = S (lengthLeft p)
lengthLeft (Drop p) = lengthLeft p
export %hint
lengthRight : xs `LTE` ys -> Length ys
lengthRight End = Z
lengthRight (Keep p) = S (lengthRight p)
lengthRight (Drop p) = S (lengthRight p)
export
id : Length xs => xs `LTE` xs
id @{Z} = End
id @{S s} = Keep id
export
zero : Length xs => [<] `LTE` xs
zero @{Z} = End
zero @{S s} = Drop zero
export
single : Length xs => x `Elem` xs -> [< x] `LTE` xs
single @{S _} Here = Keep zero
single @{S _} (There p) = Drop $ single p
export
(.) : ys `LTE` zs -> xs `LTE` ys -> xs `LTE` zs
End . End = End
Keep p . Keep q = Keep (p . q)
Keep p . Drop q = Drop (p . q)
Drop p . q = Drop (p . q)
export
(++) : xs1 `LTE` ys1 -> xs2 `LTE` ys2 -> (xs1 ++ xs2) `LTE` (ys1 ++ ys2)
p ++ End = p
p ++ Keep q = Keep (p ++ q)
p ++ Drop q = Drop (p ++ q)
public export
data LTEMaskView : (lte : xs `LTE` ys) -> (mask : Nat) -> Type where
[search lte]
END : LTEMaskView End 0
KEEP : (0 _ : LTEMaskView p n) -> LTEMaskView (Keep p) (S (2 * n))
DROP : (0 _ : LTEMaskView p n) -> LTEMaskView (Drop p) (2 * n)
%name LTEMaskView p, q
record LTEMask {a : Type} (xs, ys : Scope a) where
constructor LTEM
mask : Nat
0 lte : xs `LTE` ys
0 view0 : LTEMaskView lte mask
%name LTEMask m
namespace View
private
0 lteMaskEnd' : LTEMaskView p n -> p = End -> n = 0
lteMaskEnd' END Refl = Refl
private
0 lteMaskDrop' : LTEMaskView p n -> p = Drop q -> (n' ** n = 2 * n')
lteMaskDrop' (DROP p {n = n'}) Refl = (n' ** Refl)
private
0 lteMaskEven' : {p : xs `LTE` (ys :< y)} ->
n = 2 * n' -> LTEMaskView p n -> (q ** p = Drop q)
lteMaskEven' eq (KEEP q) = absurd $ lsbMutex' eq Refl
lteMaskEven' eq (DROP q) = (_ ** Refl)
private
lteMaskEven : {0 p : xs `LTE` (ys :< y)} ->
(0 _ : LTEMaskView p (2 * n)) -> Exists (\q => p = Drop q)
lteMaskEven q =
let 0 res = lteMaskEven' Refl q in
Evidence res.fst (irrelevantEq res.snd)
private
0 fromDROP' : {lte : xs `LTE` ys} -> n = 2 * n' ->
LTEMaskView (Drop lte) n -> LTEMaskView lte n'
fromDROP' eq (DROP {n} p) =
let eq = doubleInj eq {m = n, n = n'} in
rewrite sym eq in p
private
0 fromDROP : LTEMaskView (Drop lte) (2 * n) -> LTEMaskView lte n
fromDROP = fromDROP' Refl
private
0 lteMaskOdd' : {p : (xs :< x) `LTE` (ys :< x)} -> {n' : Nat} ->
n = S (2 * n') -> LTEMaskView p n -> (q ** p = Keep q)
lteMaskOdd' eq (KEEP q) = (_ ** Refl)
lteMaskOdd' eq (DROP q) = absurd $ lsbMutex' Refl eq
lteMaskOdd' _ END impossible
private
lteMaskOdd : (0 _ : LTEMaskView p (S (2 * n))) -> Exists (\q => p = Keep q)
lteMaskOdd q =
let 0 res = lteMaskOdd' Refl q in
Evidence res.fst (irrelevantEq res.snd)
private
0 lteMaskOddHead' : {p : (xs :< x) `LTE` (ys :< y)} -> {n' : Nat} ->
n = S (2 * n') -> LTEMaskView p n -> x = y
lteMaskOddHead' eq (KEEP q) = Refl
lteMaskOddHead' eq (DROP q) = absurd $ lsbMutex' Refl eq
lteMaskOddHead' eq END impossible
private
lteMaskOddHead : {0 p : (xs :< x) `LTE` (ys :< y)} ->
(0 _ : LTEMaskView p (S (2 * n))) -> x = y
lteMaskOddHead q = irrelevantEq $ lteMaskOddHead' Refl q
private
0 fromKEEP' : {lte : xs `LTE` ys} -> n = S (2 * n') ->
LTEMaskView (Keep lte) n -> LTEMaskView lte n'
fromKEEP' eq (KEEP {n} p) =
let eq = doubleInj (injective eq) {m = n, n = n'} in
rewrite sym eq in p
private
0 fromKEEP : LTEMaskView (Keep lte) (S (2 * n)) -> LTEMaskView lte n
fromKEEP = fromKEEP' Refl
export
view : (sx : Length xs) => (sy : Length ys) =>
(m : LTEMask xs ys) -> LTEMaskView m.lte m.mask
view @{Z} @{Z} (LTEM {lte, view0, _}) =
rewrite lteNil2End lte in
rewrite lteMaskEnd' view0 (lteNil2End lte) in
END
view @{S _} @{Z} (LTEM {lte, _}) = void $ absurd lte
view @{Z} @{S sy} (LTEM mask lte view0) =
rewrite (lteNilLeftDrop lte).snd in
rewrite (lteMaskDrop' view0 (lteNilLeftDrop lte).snd).snd in
DROP $ let DROP p = view0 in p
view @{S sx} @{S sy} (LTEM mask lte view0) with (viewLsb mask)
view @{S sx} @{S sy} (LTEM (2 * n) lte view0)
| Evidence Even (Lsb0 n) with (lteMaskEven view0)
view @{S sx} @{S sy} (LTEM (2 * m) (Drop lte) view0)
| Evidence Even (Lsb0 m) | Evidence lte Refl =
DROP $ fromDROP view0
view @{S sx} @{S sy} (LTEM (S (2 * n)) lte view0)
| Evidence Odd (Lsb1 n) with (lteMaskOddHead view0)
view @{S sx} @{S sy} (LTEM (S (2 * n)) lte view0)
| Evidence Odd (Lsb1 n) | Refl with (lteMaskOdd view0)
view @{S sx} @{S sy} (LTEM (S (2 * n)) (Keep lte) view0)
| Evidence Odd (Lsb1 n) | Refl | Evidence lte Refl =
KEEP $ fromKEEP view0
public export
record Split {a : Type} (xs, ys, zs : Scope a) (p : xs `LTE` ys ++ zs) where
constructor MkSplit
{0 leftSub, rightSub : Scope a}
leftThin : leftSub `LTE` ys
rightThin : rightSub `LTE` zs
0 eqScope : xs = leftSub ++ rightSub
0 eqThin : p ~=~ leftThin ++ rightThin
export
split : (zs : Scope a) -> (p : xs `LTE` ys ++ zs) -> Split xs ys zs p
split [<] p = MkSplit p zero Refl Refl
split (zs :< z) (Keep p) with (split zs p)
split (zs :< z) (Keep (l ++ r)) | MkSplit l r Refl Refl =
MkSplit l (Keep r) Refl Refl
split (zs :< z) (Drop p) {xs} with (split zs p)
split (zs :< z) (Drop (l ++ r)) {xs = _} | MkSplit l r Refl Refl =
MkSplit l (Drop r) Refl Refl
public export
data Comp : ys `LTE` zs -> xs `LTE` ys -> xs `LTE` zs -> Type where
CEE : Comp End End End
CKK : Comp p q pq -> Comp (Keep p) (Keep q) (Keep pq)
CKD : Comp p q pq -> Comp (Keep p) (Drop q) (Drop pq)
CD0 : Comp p q pq -> Comp (Drop p) q (Drop pq)
export
comp : (p : ys `LTE` zs) -> (q : xs `LTE` ys) -> Comp p q (p . q)
comp End End = CEE
comp (Keep p) (Keep q) = CKK (comp p q)
comp (Keep p) (Drop q) = CKD (comp p q)
comp (Drop p) q = CD0 (comp p q)
export
0 compOk : Comp p q r -> r = (p . q)
compOk CEE = Refl
compOk (CKK z) = cong Keep $ compOk z
compOk (CKD z) = cong Drop $ compOk z
compOk (CD0 z) = cong Drop $ compOk z
export
compZero : (sx : Length xs) => (sy : Length ys) =>
(p : xs `LTE` ys) -> Comp p (OPE.zero @{sx}) (OPE.zero @{sy})
compZero {sx = Z, sy = Z} End = CEE
compZero {sx = S _, sy = S _} (Keep p) = CKD (compZero p)
compZero {sy = S _} (Drop p) = CD0 (compZero p)
export
compIdLeft : (sy : Length ys) =>
(p : xs `LTE` ys) -> Comp (OPE.id @{sy}) p p
compIdLeft {sy = Z} End = CEE
compIdLeft {sy = S _} (Keep p) = CKK (compIdLeft p)
compIdLeft {sy = S _} (Drop p) = CKD (compIdLeft p)
export
compIdRight : (sx : Length xs) =>
(p : xs `LTE` ys) -> Comp p (OPE.id @{sx}) p
compIdRight {sx = Z} End = CEE
compIdRight {sx = S _} (Keep p) = CKK (compIdRight p)
compIdRight (Drop p) = CD0 (compIdRight p)
export
0 compAssoc : (p : ys `LTE` zs) -> (q : xs `LTE` ys) -> (r : ws `LTE` xs) ->
p . (q . r) = (p . q) . r
compAssoc End End End = Refl
compAssoc (Keep p) (Keep q) (Keep r) = cong Keep $ compAssoc p q r
compAssoc (Keep p) (Keep q) (Drop r) = cong Drop $ compAssoc p q r
compAssoc (Keep p) (Drop q) r = cong Drop $ compAssoc p q r
compAssoc (Drop p) q r = cong Drop $ compAssoc p q r
compAssoc End (Drop _) _ impossible
public export
Scoped : Type -> Type
Scoped a = Scope a -> Type
public export
Subscope : Scope a -> Type
Subscope ys = Exists (`LTE` ys)
public export
record SubMap {a : Type} {xs, ys, zs : Scope a}
(p : xs `LTE` zs) (q : ys `LTE` zs) where
constructor SM
thin : xs `LTE` ys
0 comp : Comp q thin p
parameters (p : xs `LTE` ys)
export
subId : SubMap p p
subId = SM id (compIdRight p)
export
subZero : SubMap OPE.zero p
subZero = SM zero (compZero p)
public export
data All : (a -> Type) -> Scoped a where
Lin : All p [<]
(:<) : All p xs -> p x -> All p (xs :< x)
%name OPE.All ps, qs
export
mapAll : (forall x. p x -> q x) -> All p xs -> All q xs
mapAll f [<] = [<]
mapAll f (x :< y) = mapAll f x :< f y
export
subAll : xs `LTE` ys -> All p ys -> All p xs
subAll End [<] = [<]
subAll (Keep q) (ps :< x) = subAll q ps :< x
subAll (Drop q) (ps :< x) = subAll q ps
public export
data Cover_ : (overlap : Bool) -> xs `LTE` zs -> ys `LTE` zs -> Type where
CE : Cover_ ov End End
CL : Cover_ ov p q -> Cover_ ov (Keep p) (Drop q)
CR : Cover_ ov p q -> Cover_ ov (Drop p) (Keep q)
C2 : Cover_ ov p q -> Cover_ True (Keep p) (Keep q)
public export
Cover : xs `LTE` zs -> ys `LTE` zs -> Type
Cover = Cover_ True
public export
Partition : xs `LTE` zs -> ys `LTE` zs -> Type
Partition = Cover_ False

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module Quox.OPE.Basics
%default total
public export
Scope : Type -> Type
Scope = SnocList
public export
Scoped : Type -> Type
Scoped a = Scope a -> Type
public export
data All : (a -> Type) -> Scoped a where
Lin : All p [<]
(:<) : All p xs -> p x -> All p (xs :< x)
%name OPE.Basics.All ps, qs
public export
mapAll : (forall x. p x -> q x) -> All p xs -> All q xs
mapAll f [<] = [<]
mapAll f (x :< y) = mapAll f x :< f y

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module Quox.OPE.Comp
import Quox.OPE.Basics
import Quox.OPE.Length
import Quox.OPE.Sub
import Data.DPair
%default total
public export
data Comp : ys `Sub` zs -> xs `Sub` ys -> xs `Sub` zs -> Type where
CEE : Comp End End End
CKK : Comp p q pq -> Comp (Keep p) (Keep q) (Keep pq)
CKD : Comp p q pq -> Comp (Keep p) (Drop q) (Drop pq)
CD0 : Comp p q pq -> Comp (Drop p) q (Drop pq)
export
comp : (p : ys `Sub` zs) -> (q : xs `Sub` ys) -> Comp p q (p . q)
comp End End = CEE
comp (Keep p) (Keep q) = CKK (comp p q)
comp (Keep p) (Drop q) = CKD (comp p q)
comp (Drop p) q = CD0 (comp p q)
export
0 compOk : Comp p q r -> r = (p . q)
compOk CEE = Refl
compOk (CKK z) = cong Keep $ compOk z
compOk (CKD z) = cong Drop $ compOk z
compOk (CD0 z) = cong Drop $ compOk z
export
compZero : (sx : Length xs) => (sy : Length ys) =>
(p : xs `Sub` ys) -> Comp p (Sub.zero @{sx}) (Sub.zero @{sy})
compZero {sx = Z, sy = Z} End = CEE
compZero {sx = S _, sy = S _} (Keep p) = CKD (compZero p)
compZero {sy = S _} (Drop p) = CD0 (compZero p)
export
compIdLeft : (sy : Length ys) =>
(p : xs `Sub` ys) -> Comp (Sub.id @{sy}) p p
compIdLeft {sy = Z} End = CEE
compIdLeft {sy = S _} (Keep p) = CKK (compIdLeft p)
compIdLeft {sy = S _} (Drop p) = CKD (compIdLeft p)
export
compIdRight : (sx : Length xs) =>
(p : xs `Sub` ys) -> Comp p (Sub.id @{sx}) p
compIdRight {sx = Z} End = CEE
compIdRight {sx = S _} (Keep p) = CKK (compIdRight p)
compIdRight (Drop p) = CD0 (compIdRight p)
export
0 compAssoc : (p : ys `Sub` zs) -> (q : xs `Sub` ys) -> (r : ws `Sub` xs) ->
p . (q . r) = (p . q) . r
compAssoc End End End = Refl
compAssoc (Keep p) (Keep q) (Keep r) = cong Keep $ compAssoc p q r
compAssoc (Keep p) (Keep q) (Drop r) = cong Drop $ compAssoc p q r
compAssoc (Keep p) (Drop q) r = cong Drop $ compAssoc p q r
compAssoc (Drop p) q r = cong Drop $ compAssoc p q r
compAssoc End (Drop _) _ impossible
public export
Subscope : Scope a -> Type
Subscope ys = Exists (`Sub` ys)
public export
record SubMap {a : Type} {xs, ys, zs : Scope a}
(p : xs `Sub` zs) (q : ys `Sub` zs) where
constructor SM
thin : xs `Sub` ys
0 comp : Comp q thin p
parameters (p : xs `Sub` ys)
export
subId : SubMap p p
subId = SM id (compIdRight p)
export
subZero : SubMap Sub.zero p
subZero = SM zero (compZero p)

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module Quox.OPE.Cover
import Quox.OPE.Basics
import Quox.OPE.Length
import Quox.OPE.Sub
%default total
public export
data Cover_ : (overlap : Bool) -> xs `Sub` zs -> ys `Sub` zs -> Type where
CE : Cover_ ov End End
CL : Cover_ ov p q -> Cover_ ov (Keep p) (Drop q)
CR : Cover_ ov p q -> Cover_ ov (Drop p) (Keep q)
C2 : Cover_ ov p q -> Cover_ True (Keep p) (Keep q)
public export
Cover : xs `Sub` zs -> ys `Sub` zs -> Type
Cover = Cover_ True
public export
Partition : xs `Sub` zs -> ys `Sub` zs -> Type
Partition = Cover_ False

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module Quox.OPE.Length
import Quox.OPE.Basics
%default total
public export
data Length : Scope a -> Type where
Z : Length [<]
S : (s : Length xs) -> Length (xs :< x)
%name Length s
%builtin Natural Length
public export
(.nat) : Length xs -> Nat
(Z).nat = Z
(S s).nat = S s.nat
%transform "Length.nat" Length.(.nat) xs = believe_me xs
export
0 ok : (s : Length xs) -> s.nat = length xs
ok Z = Refl
ok (S s) = cong S $ ok s

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module Quox.OPE.Split
import Quox.OPE.Basics
import Quox.OPE.Length
import Quox.OPE.Sub
%default total
public export
record Split {a : Type} (xs, ys, zs : Scope a) (p : xs `Sub` ys ++ zs) where
constructor MkSplit
{0 leftSub, rightSub : Scope a}
leftThin : leftSub `Sub` ys
rightThin : rightSub `Sub` zs
0 eqScope : xs = leftSub ++ rightSub
0 eqThin : p ~=~ leftThin ++ rightThin
export
split : (zs : Scope a) -> (p : xs `Sub` ys ++ zs) -> Split xs ys zs p
split [<] p = MkSplit p zero Refl Refl
split (zs :< z) (Keep p) with (split zs p)
split (zs :< z) (Keep (l ++ r)) | MkSplit l r Refl Refl =
MkSplit l (Keep r) Refl Refl
split (zs :< z) (Drop p) {xs} with (split zs p)
split (zs :< z) (Drop (l ++ r)) {xs = _} | MkSplit l r Refl Refl =
MkSplit l (Drop r) Refl Refl

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module Quox.OPE.Sub
import Quox.OPE.Basics
import Quox.OPE.Length
import Quox.NatExtra
import Data.DPair
import Data.SnocList.Elem
%default total
public export
data Sub : Scope a -> Scope a -> Type where
End : [<] `Sub` [<]
Keep : xs `Sub` ys -> xs :< z `Sub` ys :< z
Drop : xs `Sub` ys -> xs `Sub` ys :< z
%name Sub p, q
export
keepInjective : Keep p = Keep q -> p = q
keepInjective Refl = Refl
export
dropInjective : Drop p = Drop q -> p = q
dropInjective Refl = Refl
-- these need to be `public export` so that
-- `id`, `zero`, and maybe others can reduce
public export %hint
lengthLeft : xs `Sub` ys -> Length xs
lengthLeft End = Z
lengthLeft (Keep p) = S (lengthLeft p)
lengthLeft (Drop p) = lengthLeft p
public export %hint
lengthRight : xs `Sub` ys -> Length ys
lengthRight End = Z
lengthRight (Keep p) = S (lengthRight p)
lengthRight (Drop p) = S (lengthRight p)
export
dropLast : (xs :< x) `Sub` ys -> xs `Sub` ys
dropLast (Keep p) = Drop p
dropLast (Drop p) = Drop $ dropLast p
export
Uninhabited (xs :< x `Sub` [<]) where uninhabited _ impossible
export
Uninhabited (xs :< x `Sub` xs) where
uninhabited (Keep p) = uninhabited p
uninhabited (Drop p) = uninhabited $ dropLast p
export
0 lteLen : xs `Sub` ys -> length xs `LTE` length ys
lteLen End = LTEZero
lteLen (Keep p) = LTESucc $ lteLen p
lteLen (Drop p) = lteSuccRight $ lteLen p
export
0 lteNilRight : xs `Sub` [<] -> xs = [<]
lteNilRight End = Refl
public export
id : Length xs => xs `Sub` xs
id @{Z} = End
id @{S s} = Keep id
public export
zero : Length xs => [<] `Sub` xs
zero @{Z} = End
zero @{S s} = Drop zero
public export
single : Length xs => x `Elem` xs -> [< x] `Sub` xs
single @{S _} Here = Keep zero
single @{S _} (There p) = Drop $ single p
public export
(.) : ys `Sub` zs -> xs `Sub` ys -> xs `Sub` zs
End . End = End
Keep p . Keep q = Keep (p . q)
Keep p . Drop q = Drop (p . q)
Drop p . q = Drop (p . q)
public export
(++) : xs1 `Sub` ys1 -> xs2 `Sub` ys2 -> (xs1 ++ xs2) `Sub` (ys1 ++ ys2)
p ++ End = p
p ++ Keep q = Keep (p ++ q)
p ++ Drop q = Drop (p ++ q)
export
0 appZeroRight : (p : xs `Sub` ys) -> p ++ zero @{len} {xs = [<]} = p
appZeroRight {len = Z} p = Refl
public export
subAll : xs `Sub` ys -> All p ys -> All p xs
subAll End [<] = [<]
subAll (Keep q) (ps :< x) = subAll q ps :< x
subAll (Drop q) (ps :< x) = subAll q ps
public export
data SubMaskView : (lte : xs `Sub` ys) -> (mask : Nat) -> Type where
[search lte]
END : SubMaskView End 0
KEEP : {n : Nat} -> {0 p : xs `Sub` ys} ->
(0 v : SubMaskView p n) -> SubMaskView (Keep {z} p) (S (2 * n))
DROP : {n : Nat} -> {0 p : xs `Sub` ys} ->
(0 v : SubMaskView p n) -> SubMaskView (Drop {z} p) (2 * n)
%name SubMaskView v
public export
record SubMask {a : Type} (xs, ys : Scope a) where
constructor SubM
mask : Nat
0 lte : xs `Sub` ys
0 view0 : SubMaskView lte mask
%name SubMask m
private
0 ltemNilLeftZero' : SubMaskView {xs = [<]} lte mask -> mask = 0
ltemNilLeftZero' END = Refl
ltemNilLeftZero' (DROP v) = cong (2 *) $ ltemNilLeftZero' v
export
ltemNilLeftZero : (0 _ : SubMaskView {xs = [<]} lte mask) -> mask = 0
ltemNilLeftZero v = irrelevantEq $ ltemNilLeftZero' v
private
0 lteNilLeftDrop0 : (p : [<] `Sub` (xs :< x)) -> (q ** p = Drop q)
lteNilLeftDrop0 (Drop q) = (q ** Refl)
private
lteNilLeftDrop : (0 p : [<] `Sub` (xs :< x)) -> Exists (\q => p = Drop q)
lteNilLeftDrop q =
let 0 res = lteNilLeftDrop0 q in
Evidence res.fst (irrelevantEq res.snd)
private
0 lteNil2End : (p : [<] `Sub` [<]) -> p = End
lteNil2End End = Refl
private
0 ltemEnd' : SubMaskView p n -> p = End -> n = 0
ltemEnd' END Refl = Refl
private
0 ltemEven' : {p : xs `Sub` (ys :< y)} ->
n = 2 * n' -> SubMaskView p n -> (q ** p = Drop q)
ltemEven' eq (KEEP q) = absurd $ lsbMutex' eq Refl
ltemEven' eq (DROP q) = (_ ** Refl)
private
ltemEven : {0 p : xs `Sub` (ys :< y)} ->
(0 _ : SubMaskView p (2 * n)) -> Exists (\q => p = Drop q)
ltemEven q =
let 0 res = ltemEven' Refl q in
Evidence res.fst (irrelevantEq res.snd)
private
0 fromDROP' : {lte : xs `Sub` ys} -> n = 2 * n' ->
SubMaskView (Drop lte) n -> SubMaskView lte n'
fromDROP' eq (DROP {n} p) =
let eq = doubleInj eq {m = n, n = n'} in
rewrite sym eq in p
private
0 ltemOdd' : {p : (xs :< x) `Sub` (ys :< x)} -> {n' : Nat} ->
n = S (2 * n') -> SubMaskView p n -> (q ** p = Keep q)
ltemOdd' eq (KEEP q) = (_ ** Refl)
ltemOdd' eq (DROP q) = absurd $ lsbMutex' Refl eq
ltemOdd' eq END impossible
private
ltemOdd : (0 _ : SubMaskView p (S (2 * n))) -> Exists (\q => p = Keep q)
ltemOdd q =
let 0 res = ltemOdd' Refl q in
Evidence res.fst (irrelevantEq res.snd)
private
0 ltemOddHead' : {p : (xs :< x) `Sub` (ys :< y)} -> {n' : Nat} ->
n = S (2 * n') -> SubMaskView p n -> x = y
ltemOddHead' eq (KEEP q) = Refl
ltemOddHead' eq (DROP q) = absurd $ lsbMutex' Refl eq
ltemOddHead' eq END impossible
private
ltemOddHead : {0 p : (xs :< x) `Sub` (ys :< y)} ->
(0 _ : SubMaskView p (S (2 * n))) -> x = y
ltemOddHead q = irrelevantEq $ ltemOddHead' Refl q
private
0 fromKEEP' : {lte : xs `Sub` ys} -> n = S (2 * n') ->
SubMaskView (Keep lte) n -> SubMaskView lte n'
fromKEEP' eq (KEEP {n} p) =
let eq = doubleInj (injective eq) {m = n, n = n'} in
rewrite sym eq in p
export
view : Length xs => Length ys =>
(m : SubMask xs ys) -> SubMaskView m.lte m.mask
view @{Z} @{Z} (SubM {lte, view0, _}) =
rewrite lteNil2End lte in
rewrite ltemEnd' view0 (lteNil2End lte) in
END
view @{S _} @{Z} (SubM {lte, _}) = void $ absurd lte
view @{Z} @{S sy} (SubM mask lte view0) with (ltemNilLeftZero view0)
view @{Z} @{S sy} (SubM 0 lte view0)
| Refl with (lteNilLeftDrop lte)
view @{Z} @{S sy} (SubM 0 (Drop lte) view0)
| Refl | Evidence lte Refl =
DROP {n = 0} $ let DROP {n = 0} p = view0 in p
view @{S sx} @{S sy} (SubM mask lte view0) with (viewLsb mask)
view @{S sx} @{S sy} (SubM (2 * n) lte view0)
| Evidence Even (Lsb0 n) with (ltemEven view0)
view @{S sx} @{S sy} (SubM (2 * m) (Drop lte) view0)
| Evidence Even (Lsb0 m) | Evidence lte Refl =
DROP $ fromDROP' Refl view0
view @{S sx} @{S sy} (SubM (S (2 * n)) lte view0)
| Evidence Odd (Lsb1 n) with (ltemOddHead view0)
view @{S sx} @{S sy} (SubM (S (2 * n)) lte view0)
| Evidence Odd (Lsb1 n) | Refl with (ltemOdd view0)
view @{S sx} @{S sy} (SubM (S (2 * n)) (Keep lte) view0)
| Evidence Odd (Lsb1 n) | Refl | Evidence lte Refl =
KEEP $ fromKEEP' Refl view0
export
(.view) : Length xs => Length ys =>
(m : SubMask xs ys) -> SubMaskView m.lte m.mask
(.view) = view
export
ltemLen : Length xs => Length ys =>
xs `SubMask` ys -> length xs `LTE` length ys
ltemLen @{sx} @{sy} lte@(SubM m l _) with (lte.view)
ltemLen @{sx} @{sy} lte@(SubM 0 End _) | END = LTEZero
ltemLen @{S sx} @{S sy} lte@(SubM (S (2 * n)) (Keep p) _) | (KEEP q) =
LTESucc $ ltemLen $ SubM n p q
ltemLen @{sx} @{S sy} lte@(SubM (2 * n) (Drop p) _) | (DROP q) =
lteSuccRight $ ltemLen $ SubM n p q
export
ltemNilRight : xs `SubMask` [<] -> xs = [<]
ltemNilRight m = irrelevantEq $ lteNilRight m.lte

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@ -2,7 +2,6 @@ module Quox.Syntax.Var
import Quox.Name import Quox.Name
import Quox.Pretty import Quox.Pretty
import Quox.OPE
import Data.Nat import Data.Nat
import Data.List import Data.List

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@ -11,6 +11,12 @@ modules =
Quox.NatExtra, Quox.NatExtra,
Quox.Unicode, Quox.Unicode,
Quox.OPE, Quox.OPE,
Quox.OPE.Basics,
Quox.OPE.Length,
Quox.OPE.Sub,
Quox.OPE.Split,
Quox.OPE.Comp,
Quox.OPE.Cover,
Quox.Pretty, Quox.Pretty,
Quox.Syntax, Quox.Syntax,
Quox.Syntax.Dim, Quox.Syntax.Dim,