+Definition getU : UniqM Unique :=
+ uniqM (fun us => let (us1,us2) := splitUniqSupply us in OK (us1,(uniqFromSupply us2))).
+
+Notation "'bind' x = e ; f" := (@bindM _ _ _ _ e (fun x => f)) (x ident, at level 60, right associativity).
+Notation "'return' x" := (returnM x) (at level 100).
+Notation "'failM' x" := (uniqM (fun _ => Error x)) (at level 100).
+
+Section HaskStrongToWeak.
+
+ Context (hetmet_brak : WeakExprVar).
+ Context (hetmet_esc : WeakExprVar).
+
+ Context (mkWeakTypeVar_ : Unique -> Kind -> WeakTypeVar).
+ Context (mkWeakCoerVar_ : Unique -> Kind -> WeakType -> WeakType -> WeakCoerVar).
+ Context (mkWeakExprVar_ : Unique -> WeakType -> WeakExprVar).
+
+ Definition mkWeakTypeVar (k:Kind) : UniqM WeakTypeVar := bind u = getU ; return mkWeakTypeVar_ u k.
+ Definition mkWeakCoerVar (k:Kind)(t1 t2:WeakType) : UniqM WeakCoerVar := bind u = getU ; return mkWeakCoerVar_ u k t1 t2.
+ Definition mkWeakExprVar (t:WeakType) : UniqM WeakExprVar := bind u = getU ; return mkWeakExprVar_ u t.
+
+ Fixpoint mfresh (lk:list Kind){Γ}(ite:IList _ (fun _ => WeakTypeVar) Γ)
+ : UniqM (((vec WeakTypeVar (length lk)) * (IList _ (fun _ => WeakTypeVar) (app lk Γ)))) :=
+ match lk as LK return UniqM ((vec WeakTypeVar (length LK)) * (IList _ (fun _ => WeakTypeVar) (app LK Γ))) with
+ | nil => return (vec_nil,ite)
+ | k::lk' => bind v = mkWeakTypeVar k
+ ; bind vars_ite' = mfresh lk' ite
+ ; return ((v:::(fst vars_ite')),v::::(snd vars_ite'))
+ end.
+
+ Fixpoint rawHaskTypeToWeakType {κ}(rht:RawHaskType (fun _ => WeakTypeVar) κ) {struct rht} : UniqM WeakType :=
+ match rht with
+ | TVar _ v => return WTyVarTy v
+ | TCon tc => return WTyCon tc
+ | TCoerc _ t1 t2 t3 => bind t1' = rawHaskTypeToWeakType t1
+ ; bind t2' = rawHaskTypeToWeakType t2
+ ; bind t3' = rawHaskTypeToWeakType t3
+ ; return WCoFunTy t1' t2' t3'
+ | TArrow => return WFunTyCon
+ | TApp _ _ t1 t2 => bind t1' = rawHaskTypeToWeakType t1
+ ; bind t2' = rawHaskTypeToWeakType t2
+ ; return WAppTy t1' t2'
+ | TAll k rht' => bind tv = mkWeakTypeVar k
+ ; bind t' = rawHaskTypeToWeakType (rht' tv)
+ ; return WForAllTy tv t'
+ | TCode t1 t2 => bind t1' = rawHaskTypeToWeakType t1
+ ; bind t2' = rawHaskTypeToWeakType t2
+ ; match t1' with
+ | WTyVarTy ec => return WCodeTy ec t2'
+ | _ => failM "impossible"
+ end
+ | TyFunApp tfc tls => bind tls' = rawHaskTypeListToWeakType tls
+ ; return WTyFunApp tfc tls'
+ end
+ with rawHaskTypeListToWeakType {κ}(rht:RawHaskTypeList κ) : UniqM (list WeakType) :=
+ match rht with
+ | TyFunApp_nil => return nil
+ | TyFunApp_cons κ kl rht' rhtl' => bind t = rawHaskTypeToWeakType rht'
+ ; bind tl = rawHaskTypeListToWeakType rhtl'
+ ; return t::tl
+ end.
+
+ Definition typeToWeakType {Γ}{κ}(τ:HaskType Γ κ)(φ:InstantiatedTypeEnv (fun _ => WeakTypeVar) Γ) : UniqM WeakType :=
+ rawHaskTypeToWeakType (τ _ φ).
+
+ Definition updateITE {Γ:TypeEnv}{TV:Kind->Type}{κ}(tv:TV κ)(ite:InstantiatedTypeEnv TV Γ) : InstantiatedTypeEnv TV (κ::Γ)
+ := tv::::ite.
+
+ Definition coercionToWeakCoercion Γ Δ κ t1 t2 ite (γ:@HaskCoercion Γ Δ (@mkHaskCoercionKind Γ κ t1 t2))
+ : UniqM WeakCoercion
+ := bind t1' = @typeToWeakType Γ κ t1 ite
+ ; bind t2' = @typeToWeakType Γ κ t2 ite
+ ; return WCoUnsafe t1' t2'.
+
+ Fixpoint seqM {a}(l:list (UniqM a)) : UniqM (list a) :=
+ match l with
+ | nil => return nil
+ | x::y => bind x' = x
+ ; bind y' = seqM y
+ ; return x'::y'
+ end.
+
+ Context {VV}{eqVV:EqDecidable VV}{toStringVV:ToString VV}.
+
+ Definition update_χ (χ:VV->???WeakExprVar)(vv:VV)(ev':WeakExprVar) : VV->???WeakExprVar :=
+ fun vv' =>
+ if eqd_dec vv vv'
+ then OK ev'
+ else χ vv'.
+
+ Fixpoint update_χ' (χ:VV->???WeakExprVar)(varsexprs:list (VV * WeakExprVar)) : VV->???WeakExprVar :=
+ match varsexprs with
+ | nil => χ
+ | (vv,wev)::rest => update_χ (update_χ' χ rest) vv wev
+ end.
+
+ Fixpoint exprToWeakExpr {Γ}{Δ}{ξ}{τ}(χ:VV->???WeakExprVar)(exp:@Expr _ eqVV Γ Δ ξ τ)
+ : InstantiatedTypeEnv (fun _ => WeakTypeVar) Γ
+ -> UniqM WeakExpr :=
+ match exp as E in @Expr _ _ G D X L return InstantiatedTypeEnv (fun _ => WeakTypeVar) G -> UniqM WeakExpr with
+ | EVar Γ' _ ξ' ev => fun ite => match χ ev with OK v => return WEVar v | Error s => failM s end
+ | EGlobal Γ' _ ξ' t wev => fun ite => return WEVar wev
+ | ELam Γ' _ _ tv _ _ cv e => fun ite => bind tv' = typeToWeakType tv ite
+ ; bind ev' = mkWeakExprVar tv'
+ ; bind e' = exprToWeakExpr (update_χ χ cv ev') e ite
+ ; return WELam ev' e'
+ | ELet Γ' _ _ t _ _ ev e1 e2 => fun ite => bind tv' = typeToWeakType t ite
+ ; bind e1' = exprToWeakExpr χ e1 ite
+ ; bind ev' = mkWeakExprVar tv'
+ ; bind e2' = exprToWeakExpr (update_χ χ ev ev') e2 ite
+ ; return WELet ev' e1' e2'
+ | ELit _ _ _ lit _ => fun ite => return WELit lit
+ | EApp Γ' _ _ _ _ _ e1 e2 => fun ite => bind e1' = exprToWeakExpr χ e1 ite
+ ; bind e2' = exprToWeakExpr χ e2 ite
+ ; return WEApp e1' e2'
+ | EEsc Γ' _ _ ec t _ e => fun ite => bind t' = typeToWeakType t ite
+ ; bind e' = exprToWeakExpr χ e ite
+ ; return WEEsc hetmet_esc (ec _ ite) e' t'
+ | EBrak Γ' _ _ ec t _ e => fun ite => bind t' = typeToWeakType t ite
+ ; bind e' = exprToWeakExpr χ e ite
+ ; return WEBrak hetmet_brak (ec _ ite) e' t'
+ | ENote _ _ _ _ n e => fun ite => bind e' = exprToWeakExpr χ e ite
+ ; return WENote n e'
+ | ETyApp Γ Δ κ σ τ ξ l e => fun ite => bind t' = typeToWeakType τ ite
+ ; bind e' = exprToWeakExpr χ e ite
+ ; return WETyApp e' t'
+ | ECoApp Γ Δ κ σ₁ σ₂ γ σ ξ l e => fun ite => bind e' = exprToWeakExpr χ e ite
+ ; bind c' = coercionToWeakCoercion _ _ _ _ _ ite γ
+ ; return WECoApp e' c'
+ | ECast Γ Δ ξ t1 t2 γ l e => fun ite => bind e' = exprToWeakExpr χ e ite
+ ; bind c' = coercionToWeakCoercion _ _ _ _ _ ite γ
+ ; return WECast e' c'
+ | ETyLam _ _ _ k _ _ e => fun ite => bind tv = mkWeakTypeVar k
+ ; bind e' = exprToWeakExpr χ e (updateITE tv ite)
+ ; return WETyLam tv e'
+ | ECoLam Γ Δ κ σ σ₁ σ₂ ξ l e => fun ite => bind t1' = typeToWeakType σ₁ ite
+ ; bind t2' = typeToWeakType σ₂ ite
+ ; bind cv = mkWeakCoerVar κ t1' t2'
+ ; bind e' = exprToWeakExpr χ e ite
+ ; return WECoLam cv e'
+ | ECase Γ Δ ξ l tc tbranches atypes escrut alts =>
+ fun ite => bind tscrut' = typeToWeakType (caseType tc atypes) ite
+ ; bind vscrut' = mkWeakExprVar tscrut'
+ ; bind tbranches' = @typeToWeakType Γ _ tbranches ite
+ ; bind escrut' = exprToWeakExpr χ escrut ite
+ ; bind branches' =
+ ((fix caseBranches (tree:Tree ??{scb : StrongCaseBranchWithVVs VV _ _ _ & Expr _ _ _ _ })
+ : UniqM (Tree ??(WeakAltCon*list WeakTypeVar*list WeakCoerVar*list WeakExprVar*WeakExpr)) :=
+ match tree with
+ | T_Leaf None => return []
+ | T_Leaf (Some x) => let (scb,e) := x in
+ let varstypes := vec2list (scbwv_varstypes scb) in
+ bind evars_ite = mfresh _ ite
+ ; bind exprvars = seqM (map (fun vt:VV * HaskType _ ★
+ => bind tleaf = typeToWeakType (snd vt) (snd evars_ite)
+ ; bind v' = mkWeakExprVar tleaf
+ ; return ((fst vt),v'))
+ varstypes)
+ ; let χ' := update_χ' χ exprvars in
+ bind e'' = exprToWeakExpr χ' e (snd evars_ite)
+ ; return [(sac_altcon scb, vec2list (fst evars_ite), nil, (map (@snd _ _) exprvars), e'')]
+ | T_Branch b1 b2 => bind b1' = caseBranches b1
+ ; bind b2' = caseBranches b2
+ ; return (b1',,b2')
+ end) alts)
+ ; bind tys = seqM (ilist_to_list (@ilmap _ _
+ (fun _ => UniqM WeakType) _ (fun _ t => typeToWeakType t ite) atypes))
+ ; return WECase vscrut' escrut' tbranches' tc tys branches'
+
+ | ELetRec _ _ _ _ _ vars elrb e => fun ite => bind vars' = seqM (map (fun vt:VV * HaskType _ ★
+ => bind tleaf = typeToWeakType (snd vt) ite
+ ; bind v' = mkWeakExprVar tleaf
+ ; return ((fst vt),v'))
+ (leaves vars))
+ ; let χ' := update_χ' χ vars' in
+ bind elrb' = exprLetRec2WeakExprLetRec χ' elrb ite
+ ; bind e' = exprToWeakExpr χ' e ite
+ ; return WELetRec elrb' e'