257 lines
8.2 KiB
Idris
257 lines
8.2 KiB
Idris
module Quox.Reduce
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import Quox.No
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import Quox.Syntax
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import Quox.Definition
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import Data.SnocVect
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import Data.Maybe
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import Data.List
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%default total
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||| errors that might happen if you pass an ill typed expression into
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||| whnf. don't do that please
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public export
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data WhnfError = MissingEnumArm TagVal (List TagVal)
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public export
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0 RedexTest : TermLike -> Type
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RedexTest tm = forall q, g. {d, n : Nat} -> Definitions' q g -> tm q d n -> Bool
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public export
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interface Whnf (0 tm : TermLike) (0 isRedex : RedexTest tm) (0 err : Type) | tm
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where
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whnf : {d, n : Nat} -> (defs : Definitions' q g) ->
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tm q d n -> Either err (Subset (tm q d n) (No . isRedex defs))
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public export
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0 IsRedex, NotRedex : {isRedex : RedexTest tm} -> Whnf tm isRedex err =>
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Definitions' q g -> Pred (tm q d n)
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IsRedex defs = So . isRedex defs
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NotRedex defs = No . isRedex defs
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public export
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0 NonRedex : (tm : TermLike) -> {isRedex : RedexTest tm} ->
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Whnf tm isRedex err =>
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(q : Type) -> (d, n : Nat) -> {g : _} ->
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(defs : Definitions' q g) -> Type
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NonRedex tm q d n defs = Subset (tm q d n) (NotRedex defs)
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public export %inline
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nred : {0 isRedex : RedexTest tm} -> (0 _ : Whnf tm isRedex err) =>
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(t : tm q d n) -> (0 nr : NotRedex defs t) =>
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NonRedex tm q d n defs
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nred t = Element t nr
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public export %inline
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isLamHead : Elim {} -> Bool
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isLamHead (Lam {} :# Pi {}) = True
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isLamHead _ = False
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public export %inline
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isDLamHead : Elim {} -> Bool
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isDLamHead (DLam {} :# Eq {}) = True
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isDLamHead _ = False
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public export %inline
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isPairHead : Elim {} -> Bool
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isPairHead (Pair {} :# Sig {}) = True
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isPairHead _ = False
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public export %inline
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isTagHead : Elim {} -> Bool
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isTagHead (Tag t :# Enum _) = True
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isTagHead _ = False
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public export %inline
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isNatHead : Elim {} -> Bool
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isNatHead (Zero :# Nat) = True
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isNatHead (Succ n :# Nat) = True
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isNatHead _ = False
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public export %inline
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isBoxHead : Elim {} -> Bool
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isBoxHead (Box {} :# BOX {}) = True
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isBoxHead _ = False
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public export %inline
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isE : Term {} -> Bool
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isE (E _) = True
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isE _ = False
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public export %inline
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isAnn : Elim {} -> Bool
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isAnn (_ :# _) = True
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isAnn _ = False
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mutual
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public export
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isRedexE : RedexTest Elim
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isRedexE defs (F x) {d, n} =
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isJust $ lookupElim x defs {d, n}
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isRedexE _ (B _) = False
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isRedexE defs (f :@ _) =
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isRedexE defs f || isLamHead f
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isRedexE defs (CasePair {pair, _}) =
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isRedexE defs pair || isPairHead pair
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isRedexE defs (CaseEnum {tag, _}) =
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isRedexE defs tag || isTagHead tag
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isRedexE defs (CaseNat {nat, _}) =
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isRedexE defs nat || isNatHead nat
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isRedexE defs (CaseBox {box, _}) =
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isRedexE defs box || isBoxHead box
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isRedexE defs (f :% _) =
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isRedexE defs f || isDLamHead f
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isRedexE defs (t :# a) =
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isE t || isRedexT defs t || isRedexT defs a
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isRedexE _ (CloE {}) = True
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isRedexE _ (DCloE {}) = True
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public export
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isRedexT : RedexTest Term
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isRedexT _ (CloT {}) = True
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isRedexT _ (DCloT {}) = True
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isRedexT defs (E e) = isAnn e || isRedexE defs e
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isRedexT _ _ = False
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mutual
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export covering
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Whnf Elim Reduce.isRedexE WhnfError where
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whnf defs (F x) with (lookupElim x defs) proof eq
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_ | Just y = whnf defs y
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_ | Nothing = pure $ Element (F x) $ rewrite eq in Ah
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whnf _ (B i) = pure $ nred $ B i
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-- ((λ x ⇒ t) ∷ (π.x : A) → B) s ⇝ t[s∷A/x] ∷ B[s∷A/x]
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whnf defs (f :@ s) = do
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Element f fnf <- whnf defs f
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case nchoose $ isLamHead f of
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Left _ =>
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let Lam body :# Pi {arg, res, _} = f
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s = s :# arg
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in
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whnf defs $ sub1 body s :# sub1 res s
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Right nlh => pure $ Element (f :@ s) $ fnf `orNo` nlh
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-- case (s, t) ∷ (x : A) × B return p ⇒ C of { (a, b) ⇒ u } ⇝
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-- u[s∷A/a, t∷B[s∷A/x]] ∷ C[(s, t)∷((x : A) × B)/p]
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whnf defs (CasePair pi pair ret body) = do
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Element pair pairnf <- whnf defs pair
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case nchoose $ isPairHead pair of
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Left _ =>
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let Pair {fst, snd} :# Sig {fst = tfst, snd = tsnd, _} = pair
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fst = fst :# tfst
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snd = snd :# sub1 tsnd fst
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in
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whnf defs $ subN body [< fst, snd] :# sub1 ret pair
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Right np =>
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pure $ Element (CasePair pi pair ret body)
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(pairnf `orNo` np)
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-- case 'a ∷ {a,…} return p ⇒ C of { 'a ⇒ u } ⇝
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-- u ∷ C['a∷{a,…}/p]
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whnf defs (CaseEnum pi tag ret arms) = do
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Element tag tagnf <- whnf defs tag
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case nchoose $ isTagHead tag of
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Left t =>
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let Tag t :# Enum ts = tag
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ty = sub1 ret tag
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in
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case lookup t arms of
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Just arm => whnf defs $ arm :# ty
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Nothing => Left $ MissingEnumArm t (keys arms)
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Right nt =>
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pure $ Element (CaseEnum pi tag ret arms) $ tagnf `orNo` nt
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-- case zero ∷ ℕ return p ⇒ C of { zero ⇒ u; … } ⇝
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-- u ∷ C[zero∷ℕ/p]
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--
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-- case succ n ∷ ℕ return p ⇒ C of { succ n' [π.ih] ⇒ u; … } ⇝
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-- u[n∷ℕ/n', (case n ∷ ℕ ⋯)/ih] ∷ C[succ n ∷ ℕ/p]
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whnf defs (CaseNat pi piIH nat ret zer suc) = do
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Element nat natnf <- whnf defs nat
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case nchoose $ isNatHead nat of
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Left _ =>
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let ty = sub1 ret nat in
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case nat of
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Zero :# Nat => whnf defs (zer :# ty)
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Succ n :# Nat =>
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let nn = n :# Nat
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tm = subN suc [< nn, CaseNat pi piIH nn ret zer suc]
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in
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whnf defs $ tm :# ty
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Right nn =>
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pure $ Element (CaseNat pi piIH nat ret zer suc) $ natnf `orNo` nn
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-- case [t] ∷ [π.A] return p ⇒ C of { [x] ⇒ u } ⇝
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-- u[t∷A/x] ∷ C[[t] ∷ [π.A]/p]
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whnf defs (CaseBox pi box ret body) = do
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Element box boxnf <- whnf defs box
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case nchoose $ isBoxHead box of
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Left _ =>
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let Box val :# BOX q bty = box
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ty = sub1 ret box
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in
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whnf defs $ sub1 body (val :# bty) :# ty
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Right nb =>
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pure $ Element (CaseBox pi box ret body) $ boxnf `orNo` nb
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-- ((δ 𝑖 ⇒ s) ∷ Eq [𝑗 ⇒ A] t u) @0 ⇝ t ∷ A‹0/𝑗›
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-- ((δ 𝑖 ⇒ s) ∷ Eq [𝑗 ⇒ A] t u) @1 ⇝ u ∷ A‹1/𝑗›
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-- ((δ 𝑖 ⇒ s) ∷ Eq [𝑗 ⇒ A] t u) @𝑘 ⇝ s‹𝑘/𝑖› ∷ A‹𝑘/𝑗›
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-- (if 𝑘 is a variable)
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whnf defs (f :% p) = do
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Element f fnf <- whnf defs f
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case nchoose $ isDLamHead f of
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Left _ =>
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let DLam body :# Eq {ty = ty, l, r, _} = f
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body = endsOr l r (dsub1 body p) p
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in
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whnf defs $ body :# dsub1 ty p
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Right ndlh =>
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pure $ Element (f :% p) $ fnf `orNo` ndlh
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-- e ∷ A ⇝ e
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whnf defs (s :# a) = do
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Element s snf <- whnf defs s
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case nchoose $ isE s of
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Left _ => let E e = s in pure $ Element e $ noOr2 snf
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Right ne => do
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Element a anf <- whnf defs a
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pure $ Element (s :# a) $ ne `orNo` snf `orNo` anf
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whnf defs (CloE el th) = whnf defs $ pushSubstsWith' id th el
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whnf defs (DCloE el th) = whnf defs $ pushSubstsWith' th id el
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export covering
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Whnf Term Reduce.isRedexT WhnfError where
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whnf _ t@(TYPE {}) = pure $ nred t
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whnf _ t@(Pi {}) = pure $ nred t
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whnf _ t@(Lam {}) = pure $ nred t
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whnf _ t@(Sig {}) = pure $ nred t
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whnf _ t@(Pair {}) = pure $ nred t
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whnf _ t@(Enum {}) = pure $ nred t
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whnf _ t@(Tag {}) = pure $ nred t
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whnf _ t@(Eq {}) = pure $ nred t
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whnf _ t@(DLam {}) = pure $ nred t
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whnf _ Nat = pure $ nred Nat
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whnf _ Zero = pure $ nred Zero
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whnf _ t@(Succ {}) = pure $ nred t
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whnf _ t@(BOX {}) = pure $ nred t
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whnf _ t@(Box {}) = pure $ nred t
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-- s ∷ A ⇝ s (in term context)
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whnf defs (E e) = do
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Element e enf <- whnf defs e
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case nchoose $ isAnn e of
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Left _ => let tm :# _ = e in pure $ Element tm $ noOr1 $ noOr2 enf
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Right na => pure $ Element (E e) $ na `orNo` enf
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whnf defs (CloT tm th) = whnf defs $ pushSubstsWith' id th tm
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whnf defs (DCloT tm th) = whnf defs $ pushSubstsWith' th id tm
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