diff --git a/sledge/cli/smtlib.ml b/sledge/cli/smtlib.ml
index e4ea4eb9c..df9320019 100644
--- a/sledge/cli/smtlib.ml
+++ b/sledge/cli/smtlib.ml
@@ -53,7 +53,7 @@ and x_trm : var_env -> Smt.Ast.term -> Term.t =
  fun n term ->
   match term with
   | Const s -> (
-    try VarEnv.find_exn n s
+    try VarEnv.find_exn s n
     with _ -> (
       try Term.rational (Q.of_string s)
       with _ -> (
diff --git a/sledge/nonstdlib/map.ml b/sledge/nonstdlib/map.ml
index 45d0b1437..4fd91df2c 100644
--- a/sledge/nonstdlib/map.ml
+++ b/sledge/nonstdlib/map.ml
@@ -34,22 +34,26 @@ end) : S with type key = Key.t = struct
 
   let empty = M.empty
   let singleton = M.singleton
-  let add_exn m ~key ~data = M.add key data m
-  let set m ~key ~data = M.add key data m
 
-  let add_multi m ~key ~data =
+  let add_exn ~key ~data m =
+    assert (not (M.mem key m)) ;
+    M.add key data m
+
+  let add ~key ~data m = M.add key data m
+
+  let add_multi ~key ~data m =
     M.update key
       (function Some vs -> Some (data :: vs) | None -> Some [data])
       m
 
-  let remove m key = M.remove key m
-  let merge l r ~f = M.merge_safe l r ~f:(fun key -> f ~key)
+  let remove key m = M.remove key m
+  let merge l r ~f = M.merge_safe l r ~f
 
   let merge_endo t u ~f =
     let change = ref false in
     let t' =
-      merge t u ~f:(fun ~key side ->
-          let f_side = f ~key side in
+      merge t u ~f:(fun key side ->
+          let f_side = f key side in
           ( match (side, f_side) with
           | (`Both (data, _) | `Left data), Some data' when data' == data ->
               ()
@@ -58,9 +62,6 @@ end) : S with type key = Key.t = struct
     in
     if !change then t' else t
 
-  let merge_skewed x y ~combine =
-    M.union (fun key v1 v2 -> Some (combine ~key v1 v2)) x y
-
   let union x y ~f = M.union f x y
   let partition m ~f = M.partition f m
   let is_empty = M.is_empty
@@ -103,13 +104,6 @@ end) : S with type key = Key.t = struct
     | None -> false
 
   let length = M.cardinal
-  let choose_key = root_key
-  let choose = root_binding
-  let choose_exn m = Option.get_exn (choose m)
-  let min_binding = M.min_binding_opt
-  let mem m k = M.mem k m
-  let find_exn m k = M.find k m
-  let find m k = M.find_opt k m
 
   let only_binding m =
     match root_key m with
@@ -127,10 +121,18 @@ end) : S with type key = Key.t = struct
       | l, Some v, r when is_empty l && is_empty r -> `One (k, v)
       | _ -> `Many )
 
-  let find_multi m k =
+  let choose_key = root_key
+  let choose = root_binding
+  let choose_exn m = Option.get_exn (choose m)
+  let min_binding = M.min_binding_opt
+  let mem k m = M.mem k m
+  let find_exn k m = M.find k m
+  let find k m = M.find_opt k m
+
+  let find_multi k m =
     match M.find_opt k m with None -> [] | Some vs -> vs
 
-  let find_and_remove m k =
+  let find_and_remove k m =
     let found = ref None in
     let m =
       M.update k
@@ -141,13 +143,13 @@ end) : S with type key = Key.t = struct
     in
     Option.map ~f:(fun v -> (v, m)) !found
 
-  let pop m = choose m |> Option.map ~f:(fun (k, v) -> (k, v, remove m k))
+  let pop m = choose m |> Option.map ~f:(fun (k, v) -> (k, v, remove k m))
 
   let pop_min_binding m =
-    min_binding m |> Option.map ~f:(fun (k, v) -> (k, v, remove m k))
+    min_binding m |> Option.map ~f:(fun (k, v) -> (k, v, remove k m))
 
-  let change m key ~f = M.update key f m
-  let update m k ~f = M.update k (fun v -> Some (f v)) m
+  let change k m ~f = M.update k f m
+  let update k m ~f = M.update k (fun v -> Some (f v)) m
   let map m ~f = M.map f m
   let mapi m ~f = M.mapi (fun key data -> f ~key ~data) m
   let map_endo t ~f = map_endo map t ~f
@@ -157,9 +159,9 @@ end) : S with type key = Key.t = struct
   let existsi m ~f = M.exists (fun key data -> f ~key ~data) m
   let for_alli m ~f = M.for_all (fun key data -> f ~key ~data) m
   let fold m ~init ~f = M.fold (fun key data acc -> f ~key ~data acc) m init
-  let to_alist ?key_order:_ = M.to_list
-  let data m = Iter.to_list (M.values m)
-  let to_iter = M.to_iter
+  let keys = M.keys
+  let values = M.values
+  let to_iter m = Iter.rev (M.to_iter m)
 
   let to_iter2 l r =
     let seq = ref Iter.empty in
@@ -169,10 +171,10 @@ end) : S with type key = Key.t = struct
     |> ignore ;
     !seq
 
-  let symmetric_diff ~data_equal l r =
+  let symmetric_diff l r ~eq =
     Iter.filter_map (to_iter2 l r) ~f:(fun (k, vv) ->
         match vv with
-        | `Both (lv, rv) when data_equal lv rv -> None
+        | `Both (lv, rv) when eq lv rv -> None
         | `Both vv -> Some (k, `Unequal vv)
         | `Left lv -> Some (k, `Left lv)
         | `Right rv -> Some (k, `Right rv) )
@@ -181,9 +183,9 @@ end) : S with type key = Key.t = struct
     Format.fprintf fs "@[<1>[%a]@]"
       (List.pp ",@ " (fun fs (k, v) ->
            Format.fprintf fs "@[%a@ @<2>↦ %a@]" pp_k k pp_v v ))
-      (to_alist m)
+      (Iter.to_list (to_iter m))
 
-  let pp_diff ~data_equal pp_key pp_val pp_diff_val fs (x, y) =
+  let pp_diff pp_key pp_val pp_diff_val ~eq fs (x, y) =
     let pp_diff_elt fs = function
       | k, `Left v ->
           Format.fprintf fs "-- [@[%a@ @<2>↦ %a@]]" pp_key k pp_val v
@@ -192,7 +194,7 @@ end) : S with type key = Key.t = struct
       | k, `Unequal vv ->
           Format.fprintf fs "[@[%a@ @<2>↦ %a@]]" pp_key k pp_diff_val vv
     in
-    let sd = Iter.to_list (symmetric_diff ~data_equal x y) in
+    let sd = Iter.to_list (symmetric_diff ~eq x y) in
     if not (List.is_empty sd) then
       Format.fprintf fs "[@[<hv>%a@]];@ " (List.pp ";@ " pp_diff_elt) sd
 end
diff --git a/sledge/nonstdlib/map_intf.ml b/sledge/nonstdlib/map_intf.ml
index e9ec394cb..035324103 100644
--- a/sledge/nonstdlib/map_intf.ml
+++ b/sledge/nonstdlib/map_intf.ml
@@ -21,16 +21,16 @@ module type S = sig
 
   val empty : 'a t
   val singleton : key -> 'a -> 'a t
-  val add_exn : 'a t -> key:key -> data:'a -> 'a t
-  val set : 'a t -> key:key -> data:'a -> 'a t
-  val add_multi : 'a list t -> key:key -> data:'a -> 'a list t
-  val remove : 'a t -> key -> 'a t
+  val add_exn : key:key -> data:'a -> 'a t -> 'a t
+  val add : key:key -> data:'a -> 'a t -> 'a t
+  val add_multi : key:key -> data:'a -> 'a list t -> 'a list t
+  val remove : key -> 'a t -> 'a t
 
   val merge :
        'a t
     -> 'b t
     -> f:
-         (   key:key
+         (   key
           -> [`Left of 'a | `Both of 'a * 'b | `Right of 'b]
           -> 'c option)
     -> 'c t
@@ -39,7 +39,7 @@ module type S = sig
        'a t
     -> 'b t
     -> f:
-         (   key:key
+         (   key
           -> [`Left of 'a | `Both of 'a * 'b | `Right of 'b]
           -> 'a option)
     -> 'a t
@@ -47,9 +47,6 @@ module type S = sig
       left argument, which enables preserving [==] if [f] preserves [==] of
       every value. *)
 
-  val merge_skewed :
-    'a t -> 'a t -> combine:(key:key -> 'a -> 'a -> 'a) -> 'a t
-
   val union : 'a t -> 'a t -> f:(key -> 'a -> 'a -> 'a option) -> 'a t
   val partition : 'a t -> f:(key -> 'a -> bool) -> 'a t * 'a t
 
@@ -74,12 +71,12 @@ module type S = sig
       equivalent maps. [O(1)]. *)
 
   val min_binding : 'a t -> (key * 'a) option
-  val mem : 'a t -> key -> bool
-  val find : 'a t -> key -> 'a option
-  val find_exn : 'a t -> key -> 'a
-  val find_multi : 'a list t -> key -> 'a list
+  val mem : key -> 'a t -> bool
+  val find : key -> 'a t -> 'a option
+  val find_exn : key -> 'a t -> 'a
+  val find_multi : key -> 'a list t -> 'a list
 
-  val find_and_remove : 'a t -> key -> ('a * 'a t) option
+  val find_and_remove : key -> 'a t -> ('a * 'a t) option
   (** Find and remove the binding for a key. *)
 
   val pop : 'a t -> (key * 'a * 'a t) option
@@ -91,8 +88,8 @@ module type S = sig
 
   (** {1 Transform} *)
 
-  val change : 'a t -> key -> f:('a option -> 'a option) -> 'a t
-  val update : 'a t -> key -> f:('a option -> 'a) -> 'a t
+  val change : key -> 'a t -> f:('a option -> 'a option) -> 'a t
+  val update : key -> 'a t -> f:('a option -> 'a) -> 'a t
   val map : 'a t -> f:('a -> 'b) -> 'b t
   val mapi : 'a t -> f:(key:key -> data:'a -> 'b) -> 'b t
 
@@ -108,14 +105,12 @@ module type S = sig
   val iteri : 'a t -> f:(key:key -> data:'a -> unit) -> unit
   val existsi : 'a t -> f:(key:key -> data:'a -> bool) -> bool
   val for_alli : 'a t -> f:(key:key -> data:'a -> bool) -> bool
-  val fold : 'a t -> init:'b -> f:(key:key -> data:'a -> 'b -> 'b) -> 'b
+  val fold : 'a t -> init:'s -> f:(key:key -> data:'a -> 's -> 's) -> 's
 
   (** {1 Convert} *)
 
-  val to_alist :
-    ?key_order:[`Increasing | `Decreasing] -> 'a t -> (key * 'a) list
-
-  val data : 'a t -> 'a list
+  val keys : 'a t -> key iter
+  val values : 'a t -> 'a iter
   val to_iter : 'a t -> (key * 'a) iter
 
   val to_iter2 :
@@ -124,9 +119,9 @@ module type S = sig
     -> (key * [`Left of 'a | `Both of 'a * 'b | `Right of 'b]) iter
 
   val symmetric_diff :
-       data_equal:('a -> 'b -> bool)
-    -> 'a t
+       'a t
     -> 'b t
+    -> eq:('a -> 'b -> bool)
     -> (key * [> `Left of 'a | `Unequal of 'a * 'b | `Right of 'b]) iter
 
   (** {1 Pretty-print} *)
@@ -134,9 +129,9 @@ module type S = sig
   val pp : key pp -> 'a pp -> 'a t pp
 
   val pp_diff :
-       data_equal:('a -> 'a -> bool)
-    -> key pp
+       key pp
     -> 'a pp
     -> ('a * 'a) pp
+    -> eq:('a -> 'a -> bool)
     -> ('a t * 'a t) pp
 end
diff --git a/sledge/nonstdlib/multiset.ml b/sledge/nonstdlib/multiset.ml
index e44935db2..7f34a9085 100644
--- a/sledge/nonstdlib/multiset.ml
+++ b/sledge/nonstdlib/multiset.ml
@@ -34,23 +34,25 @@ struct
   let sexp_of_t s =
     List.sexp_of_t
       (Sexplib.Conv.sexp_of_pair Elt.sexp_of_t Mul.sexp_of_t)
-      (M.to_alist s)
+      (Iter.to_list (M.to_iter s))
 
   let t_of_sexp elt_of_sexp sexp =
     List.fold_left
-      ~f:(fun m (key, data) -> M.add_exn m ~key ~data)
+      ~f:(fun m (key, data) -> M.add_exn ~key ~data m)
       ~init:M.empty
       (List.t_of_sexp
          (Sexplib.Conv.pair_of_sexp elt_of_sexp Mul.t_of_sexp)
          sexp)
 
-  let pp sep pp_elt fs s = List.pp sep pp_elt fs (M.to_alist s)
+  let pp sep pp_elt fs s =
+    List.pp sep pp_elt fs (Iter.to_list (M.to_iter s))
+
   let empty = M.empty
   let of_ x i = if Mul.equal Mul.zero i then empty else M.singleton x i
   let if_nz i = if Mul.equal Mul.zero i then None else Some i
 
-  let add m x i =
-    M.change m x ~f:(function
+  let add x i m =
+    M.change x m ~f:(function
       | Some j -> if_nz (Mul.add i j)
       | None -> if_nz i )
 
@@ -59,7 +61,7 @@ struct
   let union m n = M.union m n ~f:(fun _ i j -> if_nz (Mul.add i j))
 
   let diff m n =
-    M.merge m n ~f:(fun ~key:_ -> function
+    M.merge m n ~f:(fun _ -> function
       | `Both (i, j) -> if_nz (Mul.sub i j)
       | `Left i -> Some i
       | `Right j -> Some (Mul.neg j) )
@@ -72,8 +74,8 @@ struct
       M.fold m ~init:(m, m') ~f:(fun ~key:x ~data:i (m, m') ->
           let x', i' = f x i in
           if x' == x then
-            if Mul.equal i' i then (m, m') else (M.set m ~key:x ~data:i', m')
-          else (M.remove m x, add m' x' i') )
+            if Mul.equal i' i then (m, m') else (M.add ~key:x ~data:i' m, m')
+          else (M.remove x m, add x' i' m') )
     in
     union m m'
 
@@ -89,16 +91,16 @@ struct
           | Some (x', i') ->
               if x' == x then
                 if Mul.equal i' i then (m, m')
-                else (M.set m ~key:x ~data:i', m')
-              else (M.remove m x, union m' d)
-          | None -> (M.remove m x, union m' d) )
+                else (M.add ~key:x ~data:i' m, m')
+              else (M.remove x m, union m' d)
+          | None -> (M.remove x m, union m' d) )
     in
     union m m'
 
   let is_empty = M.is_empty
   let is_singleton = M.is_singleton
   let length m = M.length m
-  let count m x = match M.find m x with Some q -> q | None -> Mul.zero
+  let count x m = match M.find x m with Some q -> q | None -> Mul.zero
   let only_elt = M.only_binding
   let classify = M.classify
   let choose = M.choose
@@ -106,7 +108,7 @@ struct
   let pop = M.pop
   let min_elt = M.min_binding
   let pop_min_elt = M.pop_min_binding
-  let to_list m = M.to_alist m
+  let to_iter = M.to_iter
   let iter m ~f = M.iteri ~f:(fun ~key ~data -> f key data) m
   let exists m ~f = M.existsi ~f:(fun ~key ~data -> f key data) m
   let for_all m ~f = M.for_alli ~f:(fun ~key ~data -> f key data) m
diff --git a/sledge/nonstdlib/multiset_intf.ml b/sledge/nonstdlib/multiset_intf.ml
index 69cfa200b..fd02a86d9 100644
--- a/sledge/nonstdlib/multiset_intf.ml
+++ b/sledge/nonstdlib/multiset_intf.ml
@@ -37,10 +37,10 @@ module type S = sig
 
   val of_ : elt -> mul -> t
 
-  val add : t -> elt -> mul -> t
+  val add : elt -> mul -> t -> t
   (** Add to multiplicity of single element. [O(log n)] *)
 
-  val remove : t -> elt -> t
+  val remove : elt -> t -> t
   (** Set the multiplicity of an element to zero. [O(log n)] *)
 
   val union : t -> t -> t
@@ -74,7 +74,7 @@ module type S = sig
   val length : t -> int
   (** Number of elements with non-zero multiplicity. [O(1)]. *)
 
-  val count : t -> elt -> mul
+  val count : elt -> t -> mul
   (** Multiplicity of an element. [O(log n)]. *)
 
   val only_elt : t -> (elt * mul) option
@@ -98,11 +98,11 @@ module type S = sig
   val classify : t -> [`Zero | `One of elt * mul | `Many]
   (** Classify a set as either empty, singleton, or otherwise. *)
 
-  val find_and_remove : t -> elt -> (mul * t) option
+  val find_and_remove : elt -> t -> (mul * t) option
   (** Find and remove an element. *)
 
-  val to_list : t -> (elt * mul) list
-  (** Convert to a list of elements in ascending order. *)
+  val to_iter : t -> (elt * mul) iter
+  (** Enumerate elements in ascending order. *)
 
   (* traversals *)
 
diff --git a/sledge/src/arithmetic.ml b/sledge/src/arithmetic.ml
index 9347700dc..bf07124a4 100644
--- a/sledge/src/arithmetic.ml
+++ b/sledge/src/arithmetic.ml
@@ -235,7 +235,7 @@ module Representation (Trm : INDETERMINATE) = struct
     (* transform *)
 
     let split_const poly =
-      match Sum.find_and_remove poly Mono.one with
+      match Sum.find_and_remove Mono.one poly with
       | Some (c, p_c) -> (p_c, c)
       | None -> (poly, Q.zero)
 
@@ -249,11 +249,11 @@ module Representation (Trm : INDETERMINATE) = struct
                   let trm' = f trm in
                   if trm == trm' then (m, cm')
                   else
-                    (Prod.remove m trm, CM.mul cm' (CM.of_trm trm' ~power)) )
+                    (Prod.remove trm m, CM.mul cm' (CM.of_trm trm' ~power)) )
             in
             if CM.equal_one cm' then (p, p')
             else
-              ( Sum.remove p mono
+              ( Sum.remove mono p
               , Sum.union p' (CM.to_poly (CM.mul (coeff, m) cm')) ) )
       in
       if Sum.is_empty p' then poly else Sum.union p p' |> check invariant
diff --git a/sledge/src/control.ml b/sledge/src/control.ml
index 4edee6bbb..be926c8b9 100644
--- a/sledge/src/control.ml
+++ b/sledge/src/control.ml
@@ -187,10 +187,10 @@ module Make (Dom : Domain_intf.Dom) = struct
 
       let empty = M.empty
       let find = M.find
-      let set = M.set
+      let add = M.add
 
       let join x y =
-        M.merge x y ~f:(fun ~key:_ -> function
+        M.merge x y ~f:(fun _ -> function
           | `Left d | `Right d -> Some d
           | `Both (d1, d2) -> Some (Int.max d1 d2) )
     end
@@ -215,7 +215,7 @@ module Make (Dom : Domain_intf.Dom) = struct
     let add ?prev ~retreating stk state curr depths ((pq, ws, bound) as work)
         =
       let edge = {Edge.dst= curr; src= prev; stk} in
-      let depth = Option.value (Depths.find depths edge) ~default:0 in
+      let depth = Option.value (Depths.find edge depths) ~default:0 in
       let depth = if retreating then depth + 1 else depth in
       if depth > bound then (
         [%Trace.info "prune: %i: %a" depth Edge.pp edge] ;
@@ -223,9 +223,9 @@ module Make (Dom : Domain_intf.Dom) = struct
       else
         let pq = FHeap.add pq (depth, edge) in
         [%Trace.info "@[<6>enqueue %i: %a@ | %a@]" depth Edge.pp edge pp pq] ;
-        let depths = Depths.set depths ~key:edge ~data:depth in
+        let depths = Depths.add ~key:edge ~data:depth depths in
         let ws =
-          Llair.Block.Map.add_multi ws ~key:curr ~data:(state, depths)
+          Llair.Block.Map.add_multi ~key:curr ~data:(state, depths) ws
         in
         (pq, ws, bound)
 
@@ -236,7 +236,7 @@ module Make (Dom : Domain_intf.Dom) = struct
     let rec run ~f (pq0, ws, bnd) =
       match FHeap.pop pq0 with
       | Some ((_, ({Edge.dst; stk} as edge)), pq) -> (
-        match Llair.Block.Map.find_and_remove ws dst with
+        match Llair.Block.Map.find_and_remove dst ws with
         | Some (q :: qs, ws) ->
             let join (qa, da) (q, d) = (Dom.join q qa, Depths.join d da) in
             let skipped, (qs, depths) =
@@ -245,7 +245,7 @@ module Make (Dom : Domain_intf.Dom) = struct
                   | Some joined, depths -> (skipped, (joined, depths))
                   | None, _ -> (curr :: skipped, joined) )
             in
-            let ws = Llair.Block.Map.add_exn ws ~key:dst ~data:skipped in
+            let ws = Llair.Block.Map.add_exn ~key:dst ~data:skipped ws in
             run ~f (f stk qs dst depths (pq, ws, bnd))
         | _ ->
             [%Trace.info "done: %a" Edge.pp edge] ;
@@ -330,7 +330,7 @@ module Make (Dom : Domain_intf.Dom) = struct
             ~formals:
               (Llair.Reg.Set.union (Llair.Reg.Set.of_list formals) globals)
         in
-        RegTbl.add_multi summary_table ~key:name.reg ~data:function_summary ;
+        RegTbl.add_multi ~key:name.reg ~data:function_summary summary_table ;
         pp_st () ;
         post_state
     in
@@ -432,7 +432,7 @@ module Make (Dom : Domain_intf.Dom) = struct
             | None -> x )
     | Call ({callee; actuals; areturn; return} as call) -> (
         let lookup name =
-          Option.to_list (Llair.Func.find pgm.functions name)
+          Option.to_list (Llair.Func.find name pgm.functions)
         in
         let callees, state = Dom.resolve_callee lookup callee state in
         match callees with
@@ -492,7 +492,9 @@ module Make (Dom : Domain_intf.Dom) = struct
 
   let harness : exec_opts -> Llair.program -> (int -> Work.t) option =
    fun opts pgm ->
-    List.find_map ~f:(Llair.Func.find pgm.functions) opts.entry_points
+    List.find_map
+      ~f:(fun entry_point -> Llair.Func.find entry_point pgm.functions)
+      opts.entry_points
     |> function
     | Some {name= {reg}; formals= []; freturn; locals; entry} ->
         Some
@@ -517,5 +519,5 @@ module Make (Dom : Domain_intf.Dom) = struct
     exec_pgm opts pgm ;
     RegTbl.fold summary_table ~init:Llair.Reg.Map.empty
       ~f:(fun ~key ~data map ->
-        match data with [] -> map | _ -> Llair.Reg.Map.set map ~key ~data )
+        match data with [] -> map | _ -> Llair.Reg.Map.add ~key ~data map )
 end
diff --git a/sledge/src/domain_used_globals.ml b/sledge/src/domain_used_globals.ml
index e833de63f..54edcb86e 100644
--- a/sledge/src/domain_used_globals.ml
+++ b/sledge/src/domain_used_globals.ml
@@ -111,7 +111,7 @@ let by_function : r -> Llair.Reg.t -> t =
   ( match s with
   | Declared set -> set
   | Per_function map -> (
-    match Llair.Reg.Map.find map fn with
+    match Llair.Reg.Map.find fn map with
     | Some gs -> gs
     | None ->
         fail
diff --git a/sledge/src/fol.ml b/sledge/src/fol.ml
index 2709058b5..7d070e326 100644
--- a/sledge/src/fol.ml
+++ b/sledge/src/fol.ml
@@ -1095,7 +1095,7 @@ module Context = struct
       ~f:(fun ~key:rep ~data:cls clss ->
         let rep' = of_ses rep in
         let cls' = List.map ~f:of_ses cls in
-        Term.Map.set ~key:rep' ~data:cls' clss )
+        Term.Map.add ~key:rep' ~data:cls' clss )
 
   let diff_classes r s =
     Term.Map.filter_mapi (classes r) ~f:(fun ~key:rep ~data:cls ->
@@ -1116,7 +1116,8 @@ module Context = struct
       (fun fs (rep, cls) ->
         Format.fprintf fs "@[%a@ = %a@]" (Term.ppx x) rep (ppx_cls x)
           (List.sort ~cmp:Term.compare cls) )
-      fs (Term.Map.to_alist clss)
+      fs
+      (Iter.to_list (Term.Map.to_iter clss))
 
   let pp fs r = ppx_classes (fun _ -> None) fs (classes r)
 
diff --git a/sledge/src/llair/llair.ml b/sledge/src/llair/llair.ml
index 38a012ee9..b5af535b2 100644
--- a/sledge/src/llair/llair.ml
+++ b/sledge/src/llair/llair.ml
@@ -562,8 +562,8 @@ let set_derived_metadata functions =
         | Iswitch {tbl; _} -> IArray.iter tbl ~f:jump
         | Call ({callee; return; throw; _} as call) ->
             ( match
-                Option.bind ~f:(Func.find functions)
-                  (Option.map ~f:Reg.name (Reg.of_exp callee))
+                let* reg = Reg.of_exp callee in
+                Func.find (Reg.name reg) functions
               with
             | Some func ->
                 if Block_label.Set.mem ancestors func.entry then
@@ -589,7 +589,7 @@ let set_derived_metadata functions =
   in
   let functions =
     List.fold functions ~init:String.Map.empty ~f:(fun m func ->
-        String.Map.add_exn m ~key:(Reg.name func.name.reg) ~data:func )
+        String.Map.add_exn ~key:(Reg.name func.name.reg) ~data:func m )
   in
   let roots = compute_roots functions in
   let tips_to_roots = topsort functions roots in
@@ -616,6 +616,7 @@ module Program = struct
       (IArray.pp "@\n@\n" Global.pp_defn)
       globals
       (List.pp "@\n@\n" Func.pp)
-      ( String.Map.data functions
+      ( String.Map.values functions
+      |> Iter.to_list
       |> List.sort ~cmp:(fun x y -> compare_block x.entry y.entry) )
 end
diff --git a/sledge/src/llair/llair.mli b/sledge/src/llair/llair.mli
index 7a3d29e76..9e0b0d26b 100644
--- a/sledge/src/llair/llair.mli
+++ b/sledge/src/llair/llair.mli
@@ -195,7 +195,7 @@ module Func : sig
     -> fthrow:Reg.t
     -> t
 
-  val find : functions -> string -> func option
+  val find : string -> functions -> func option
   (** Look up a function of the given name in the given functions. *)
 
   val is_undefined : func -> bool
diff --git a/sledge/src/ses/equality.ml b/sledge/src/ses/equality.ml
index 12dd90fe9..673ee3127 100644
--- a/sledge/src/ses/equality.ml
+++ b/sledge/src/ses/equality.ml
@@ -38,8 +38,8 @@ module Subst : sig
   val empty : t
   val is_empty : t -> bool
   val length : t -> int
-  val mem : t -> Term.t -> bool
-  val find : t -> Term.t -> Term.t option
+  val mem : Term.t -> t -> bool
+  val find : Term.t -> t -> Term.t option
   val fold : t -> init:'a -> f:(key:Term.t -> data:Term.t -> 'a -> 'a) -> 'a
   val iteri : t -> f:(key:Term.t -> data:Term.t -> unit) -> unit
   val for_alli : t -> f:(key:Term.t -> data:Term.t -> bool) -> bool
@@ -52,17 +52,13 @@ module Subst : sig
   val remove : Var.Set.t -> t -> t
   val map_entries : f:(Term.t -> Term.t) -> t -> t
   val to_iter : t -> (Term.t * Term.t) iter
-  val to_alist : t -> (Term.t * Term.t) list
   val partition_valid : Var.Set.t -> t -> t * Var.Set.t * t
 end = struct
   type t = Term.t Term.Map.t [@@deriving compare, equal, sexp_of]
 
   let t_of_sexp = Term.Map.t_of_sexp Term.t_of_sexp
   let pp = Term.Map.pp Term.pp Term.pp
-
-  let pp_diff =
-    Term.Map.pp_diff ~data_equal:Term.equal Term.pp Term.pp Term.pp_diff
-
+  let pp_diff = Term.Map.pp_diff ~eq:Term.equal Term.pp Term.pp Term.pp_diff
   let empty = Term.Map.empty
   let is_empty = Term.Map.is_empty
   let length = Term.Map.length
@@ -72,10 +68,9 @@ end = struct
   let iteri = Term.Map.iteri
   let for_alli = Term.Map.for_alli
   let to_iter = Term.Map.to_iter
-  let to_alist = Term.Map.to_alist ~key_order:`Increasing
 
   (** look up a term in a substitution *)
-  let apply s a = Term.Map.find s a |> Option.value ~default:a
+  let apply s a = Term.Map.find a s |> Option.value ~default:a
 
   let rec subst s a = apply s (Term.map ~f:(subst s) a)
 
@@ -88,7 +83,7 @@ end = struct
     [%Trace.call fun {pf} -> pf "%a@ %a" pp r pp s]
     ;
     let r' = Term.Map.map_endo ~f:(norm s) r in
-    Term.Map.merge_endo r' s ~f:(fun ~key -> function
+    Term.Map.merge_endo r' s ~f:(fun key -> function
       | `Both (data_r, data_s) ->
           assert (
             Term.equal data_s data_r
@@ -112,7 +107,7 @@ end = struct
   let extend e s =
     let exception Found in
     match
-      Term.Map.update s e ~f:(function
+      Term.Map.update e s ~f:(function
         | Some _ -> raise_notrace Found
         | None -> e )
     with
@@ -121,7 +116,7 @@ end = struct
 
   (** remove entries for vars *)
   let remove xs s =
-    Var.Set.fold ~f:(fun s x -> Term.Map.remove s (Term.var x)) ~init:s xs
+    Var.Set.fold ~f:(fun s x -> Term.Map.remove (Term.var x) s) ~init:s xs
 
   (** map over a subst, applying [f] to both domain and range, requires that
       [f] is injective and for any set of terms [E], [f\[E\]] is disjoint
@@ -132,9 +127,9 @@ end = struct
         let data' = f data in
         if Term.equal key' key then
           if Term.equal data' data then s
-          else Term.Map.set s ~key ~data:data'
+          else Term.Map.add ~key ~data:data' s
         else
-          let s = Term.Map.remove s key in
+          let s = Term.Map.remove key s in
           match (key : Term.t) with
           | Integer _ | Rational _ -> s
           | _ -> Term.Map.add_exn ~key:key' ~data:data' s )
@@ -167,10 +162,10 @@ end = struct
         Term.Map.fold s ~init:(t, ks, s) ~f:(fun ~key ~data (t, ks, s) ->
             if is_valid_eq ks key data then (t, ks, s)
             else
-              let t = Term.Map.set ~key ~data t
+              let t = Term.Map.add ~key ~data t
               and ks =
                 Var.Set.diff ks (Var.Set.union (Term.fv key) (Term.fv data))
-              and s = Term.Map.remove s key in
+              and s = Term.Map.remove key s in
               (t, ks, s) )
       in
       if s' != s then partition_valid_ t' ks' s' else (t', ks', s')
@@ -347,7 +342,7 @@ type classes = Term.t list Term.Map.t
 let classes r =
   let add key data cls =
     if Term.equal key data then cls
-    else Term.Map.add_multi cls ~key:data ~data:key
+    else Term.Map.add_multi ~key:data ~data:key cls
   in
   Subst.fold r.rep ~init:Term.Map.empty ~f:(fun ~key ~data cls ->
       match classify key with
@@ -356,7 +351,7 @@ let classes r =
 
 let cls_of r e =
   let e' = Subst.apply r.rep e in
-  Term.Map.find (classes r) e' |> Option.value ~default:[e']
+  Term.Map.find e' (classes r) |> Option.value ~default:[e']
 
 (** Pretty-printing *)
 
@@ -370,7 +365,7 @@ let pp fs {sat; rep} =
   let pp_term_v fs (k, v) = if not (Term.equal k v) then Term.pp fs v in
   Format.fprintf fs "@[{@[<hv>sat= %b;@ rep= %a@]}@]" sat
     (pp_alist Term.pp pp_term_v)
-    (Subst.to_alist rep)
+    (Iter.to_list (Subst.to_iter rep))
 
 let pp_diff fs (r, s) =
   let pp_sat fs =
@@ -392,18 +387,18 @@ let ppx_classes x fs clss =
     (fun fs (rep, cls) ->
       Format.fprintf fs "@[%a@ = %a@]" (Term.ppx x) rep (ppx_cls x)
         (List.sort ~cmp:Term.compare cls) )
-    fs (Term.Map.to_alist clss)
+    fs
+    (Iter.to_list (Term.Map.to_iter clss))
 
 let pp_classes fs r = ppx_classes (fun _ -> None) fs (classes r)
 
 let pp_diff_clss =
-  Term.Map.pp_diff ~data_equal:(List.equal Term.equal) Term.pp pp_cls
-    pp_diff_cls
+  Term.Map.pp_diff ~eq:(List.equal Term.equal) Term.pp pp_cls pp_diff_cls
 
 (** Basic queries *)
 
 (** test membership in carrier *)
-let in_car r e = Subst.mem r.rep e
+let in_car r e = Subst.mem e r.rep
 
 (** congruent specialized to assume subterms of [a'] are [Subst.norm]alized
     wrt [r] (or canonized) *)
@@ -575,7 +570,7 @@ let normalize = canon
 
 let class_of r e =
   let e' = normalize r e in
-  e' :: Term.Map.find_multi (classes r) e'
+  e' :: Term.Map.find_multi e' (classes r)
 
 let fold_uses_of r t ~init ~f =
   let rec fold_ e ~init:s ~f =
@@ -707,7 +702,7 @@ let subst_invariant us s0 s =
     Subst.iteri s ~f:(fun ~key ~data ->
         (* dom of new entries not ito us *)
         assert (
-          Option.for_all ~f:(Term.equal data) (Subst.find s0 key)
+          Option.for_all ~f:(Term.equal data) (Subst.find key s0)
           || not (Var.Set.is_subset (Term.fv key) ~of_:us) ) ;
         (* rep not ito us implies trm not ito us *)
         assert (
@@ -912,8 +907,8 @@ let solve_class us us_xs ~key:rep ~data:cls (classes, subst) =
   let cls = List.rev_append cls_not_ito_us_xs cls in
   let cls = List.remove ~eq:Term.equal (Subst.norm subst rep) cls in
   let classes =
-    if List.is_empty cls then Term.Map.remove classes rep
-    else Term.Map.set classes ~key:rep ~data:cls
+    if List.is_empty cls then Term.Map.remove rep classes
+    else Term.Map.add ~key:rep ~data:cls classes
   in
   (classes, subst)
   |>
@@ -980,7 +975,7 @@ let solve_for_xs r us xs (classes, subst, us_xs) =
   Var.Set.fold xs ~init:(classes, subst, us_xs)
     ~f:(fun (classes, subst, us_xs) x ->
       let x = Term.var x in
-      if Subst.mem subst x then (classes, subst, us_xs)
+      if Subst.mem x subst then (classes, subst, us_xs)
       else solve_concat_extracts r us x (classes, subst, us_xs) )
 
 (** move equations from [classes] to [subst] which can be expressed, after
diff --git a/sledge/src/ses/term.ml b/sledge/src/ses/term.ml
index 7f0b21e0e..4a2b1f57c 100644
--- a/sledge/src/ses/term.ml
+++ b/sledge/src/ses/term.ml
@@ -368,9 +368,9 @@ module Sum = struct
     assert (not (Q.equal Q.zero coeff)) ;
     match term with
     | Integer {data} when Z.equal Z.zero data -> sum
-    | Integer {data} -> Qset.add sum one Q.(coeff * of_z data)
-    | Rational {data} -> Qset.add sum one Q.(coeff * data)
-    | _ -> Qset.add sum term coeff
+    | Integer {data} -> Qset.add one Q.(coeff * of_z data) sum
+    | Rational {data} -> Qset.add one Q.(coeff * data) sum
+    | _ -> Qset.add term coeff sum
 
   let of_ ?(coeff = Q.one) term = add coeff term empty
 
@@ -403,7 +403,7 @@ module Prod = struct
 
   let add term prod =
     assert (match term with Integer _ | Rational _ -> false | _ -> true) ;
-    Qset.add prod term Q.one
+    Qset.add term Q.one prod
 
   let of_ term = add term empty
   let union = Qset.union
@@ -972,7 +972,7 @@ let d_int = function Integer {data} -> Some data | _ -> None
 
 (** Access *)
 
-let const_of = function Add poly -> Some (Qset.count poly one) | _ -> None
+let const_of = function Add poly -> Some (Qset.count one poly) | _ -> None
 
 (** Transform *)
 
@@ -1198,7 +1198,7 @@ let rec solve_sum rejected_sum sum =
   let* mono, coeff, sum = Qset.pop_min_elt sum in
   match solve_for_mono rejected_sum coeff mono sum with
   | Some _ as soln -> soln
-  | None -> solve_sum (Qset.add rejected_sum mono coeff) sum
+  | None -> solve_sum (Qset.add mono coeff rejected_sum) sum
 
 (* solve [0 = e] *)
 let solve_zero_eq ?for_ e =
@@ -1209,7 +1209,7 @@ let solve_zero_eq ?for_ e =
     match for_ with
     | None -> solve_sum Qset.empty sum
     | Some mono ->
-        let* coeff, sum = Qset.find_and_remove sum mono in
+        let* coeff, sum = Qset.find_and_remove mono sum in
         solve_for_mono Qset.empty coeff mono sum )
   | _ -> None )
   |>
diff --git a/sledge/src/ses/var0.ml b/sledge/src/ses/var0.ml
index 01a1b8c58..7f3df66fa 100644
--- a/sledge/src/ses/var0.ml
+++ b/sledge/src/ses/var0.ml
@@ -87,7 +87,7 @@ module Make (T : REPR) = struct
           Set.fold dom ~init:(empty, Set.empty, wrt)
             ~f:(fun (sub, rng, wrt) x ->
               let x', wrt = fresh (name x) ~wrt in
-              let sub = Map.add_exn sub ~key:x ~data:x' in
+              let sub = Map.add_exn ~key:x ~data:x' sub in
               let rng = Set.add rng x' in
               (sub, rng, wrt) )
         in
@@ -107,7 +107,7 @@ module Make (T : REPR) = struct
 
     let invert sub =
       Map.fold sub ~init:empty ~f:(fun ~key ~data sub' ->
-          Map.add_exn sub' ~key:data ~data:key )
+          Map.add_exn ~key:data ~data:key sub' )
       |> check invariant
 
     let restrict sub vs =
@@ -119,13 +119,13 @@ module Make (T : REPR) = struct
             assert (
               (* all substs are injective, so the current mapping is the
                  only one that can cause [data] to be in [rng] *)
-              (not (Set.mem (range (Map.remove sub key)) data))
+              (not (Set.mem (range (Map.remove key sub)) data))
               || violates invariant sub ) ;
-            {z with sub= Map.remove z.sub key} ) )
+            {z with sub= Map.remove key z.sub} ) )
       |> check (fun {sub; dom; rng} ->
              assert (Set.equal dom (domain sub)) ;
              assert (Set.equal rng (range sub)) )
 
-    let apply sub v = Map.find sub v |> Option.value ~default:v
+    let apply sub v = Map.find v sub |> Option.value ~default:v
   end
 end
diff --git a/sledge/src/sh.ml b/sledge/src/sh.ml
index 8cac3dbe0..dc6f15cd7 100644
--- a/sledge/src/sh.ml
+++ b/sledge/src/sh.ml
@@ -90,28 +90,28 @@ let fold_vars ?ignore_ctx ?ignore_pure fold_vars q ~init ~f =
 (** Pretty-printing *)
 
 let rec var_strength_ xs m q =
-  let add m v =
-    match Var.Map.find m v with
-    | None -> Var.Map.set m ~key:v ~data:`Anonymous
-    | Some `Anonymous -> Var.Map.set m ~key:v ~data:`Existential
+  let add v m =
+    match Var.Map.find v m with
+    | None -> Var.Map.add ~key:v ~data:`Anonymous m
+    | Some `Anonymous -> Var.Map.add ~key:v ~data:`Existential m
     | Some _ -> m
   in
   let xs = Var.Set.union xs q.xs in
   let m_stem =
     fold_vars_stem ~ignore_ctx:() q ~init:m ~f:(fun m var ->
         if not (Var.Set.mem xs var) then
-          Var.Map.set m ~key:var ~data:`Universal
-        else add m var )
+          Var.Map.add ~key:var ~data:`Universal m
+        else add var m )
   in
   let m =
     List.fold ~init:m_stem q.djns ~f:(fun m djn ->
         let ms = List.map ~f:(fun dj -> snd (var_strength_ xs m dj)) djn in
         List.reduce ms ~f:(fun m1 m2 ->
-            Var.Map.merge_skewed m1 m2 ~combine:(fun ~key:_ s1 s2 ->
+            Var.Map.union m1 m2 ~f:(fun _ s1 s2 ->
                 match (s1, s2) with
-                | `Anonymous, `Anonymous -> `Anonymous
-                | `Universal, _ | _, `Universal -> `Universal
-                | `Existential, _ | _, `Existential -> `Existential ) )
+                | `Anonymous, `Anonymous -> Some `Anonymous
+                | `Universal, _ | _, `Universal -> Some `Universal
+                | `Existential, _ | _, `Existential -> Some `Existential ) )
         |> Option.value ~default:m )
   in
   (m_stem, m)
@@ -119,7 +119,7 @@ let rec var_strength_ xs m q =
 let var_strength ?(xs = Var.Set.empty) q =
   let m =
     Var.Set.fold xs ~init:Var.Map.empty ~f:(fun m x ->
-        Var.Map.set m ~key:x ~data:`Existential )
+        Var.Map.add ~key:x ~data:`Existential m )
   in
   var_strength_ xs m q
 
@@ -198,7 +198,7 @@ let pp_us ?(pre = ("" : _ fmt)) ?vs () fs us =
 let rec pp_ ?var_strength vs parent_xs parent_ctx fs
     {us; xs; ctx; pure; heap; djns} =
   Format.pp_open_hvbox fs 0 ;
-  let x v = Option.bind ~f:(fun (_, m) -> Var.Map.find m v) var_strength in
+  let x v = Option.bind ~f:(fun (_, m) -> Var.Map.find v m) var_strength in
   pp_us ~vs () fs us ;
   let xs_d_vs, xs_i_vs =
     Var.Set.diff_inter