Replace the error-prone "n/range" calls with "indices".

19 files changed, 43 insertions, 50 deletions

diff --git a/stdlib/source/lux/compiler/default/phase/analysis.lux b/stdlib/source/lux/compiler/default/phase/analysis.lux
index ccf46b873..b0776141a 100644
--- a/stdlib/source/lux/compiler/default/phase/analysis.lux
+++ b/stdlib/source/lux/compiler/default/phase/analysis.lux
@@ -116,11 +116,9 @@
      (let [left (function.constant (|>> #.Left #Sum <structure>))
            right (|>> #.Right #Sum <structure>)]
        (if (last? size tag)
-         (if (n/= 1 tag)
-           (right value)
-           (list/fold left
-                      (right value)
-                      (list.n/range 0 (n/- 2 tag))))
+         (list/fold left
+                    (right value)
+                    (list.indices (dec tag)))
          (list/fold left
                     (case value
                       (<structure> (#Sum _))
@@ -128,7 +126,7 @@
 
                       _
                       value)
-                    (list.n/range 0 tag)))))]
+                    (list.indices (inc tag))))))]
 
   [sum-analysis Analysis #Structure no-op]
   [sum-pattern  Pattern  #Complex   id]
diff --git a/stdlib/source/lux/compiler/default/phase/analysis/structure.lux b/stdlib/source/lux/compiler/default/phase/analysis/structure.lux
index 2977eb777..1ef523c76 100644
--- a/stdlib/source/lux/compiler/default/phase/analysis/structure.lux
+++ b/stdlib/source/lux/compiler/default/phase/analysis/structure.lux
@@ -311,7 +311,7 @@
        _ (if (n/= size-ts size-record)
            (wrap [])
            (///.throw record-size-mismatch [size-ts size-record recordT record]))
-       #let [tuple-range (list.n/range 0 (dec size-ts))
+       #let [tuple-range (list.indices size-ts)
              tag->idx (dict.from-list name.Hash<Name> (list.zip2 tag-set tuple-range))]
        idx->val (monad.fold @
                             (function (_ [key val] idx->val)
diff --git a/stdlib/source/lux/compiler/default/phase/extension/analysis/host.jvm.lux b/stdlib/source/lux/compiler/default/phase/extension/analysis/host.jvm.lux
index 706d35e51..2713f59a2 100644
--- a/stdlib/source/lux/compiler/default/phase/extension/analysis/host.jvm.lux
+++ b/stdlib/source/lux/compiler/default/phase/extension/analysis/host.jvm.lux
@@ -604,7 +604,7 @@
                             (#.Primitive class-name (list))
                             
                             arity
-                            (|> (list.n/range 0 (dec arity))
+                            (|> (list.indices arity)
                                 list.reverse
                                 (list/map (|>> (n/* 2) inc #.Parameter))
                                 (#.Primitive class-name)
@@ -976,8 +976,8 @@
   (-> Nat Nat (List Type))
   (if (n/= 0 amount)
     (list)
-    (|> (list.n/range offset (|> amount dec (n/+ offset)))
-        (list/map idx-to-parameter))))
+    (|> (list.indices amount)
+        (list/map (|>> (n/+ offset) idx-to-parameter)))))
 
 (def: (method-signature method-style method)
   (-> Method-Style Method (Operation Method-Signature))
diff --git a/stdlib/source/lux/compiler/default/phase/synthesis/function.lux b/stdlib/source/lux/compiler/default/phase/synthesis/function.lux
index eadcd52b0..8a85b9873 100644
--- a/stdlib/source/lux/compiler/default/phase/synthesis/function.lux
+++ b/stdlib/source/lux/compiler/default/phase/synthesis/function.lux
@@ -107,7 +107,9 @@
                                  (list)
                                  
                                  _
-                                 (|> (list.size environment) dec (list.n/range 0)
+                                 (|> environment
+                                     list.size
+                                     list.indices
                                      (list/map (|>> #reference.Foreign)))))
            resolver' (if (and (nested? function-arity)
                               direct?)
diff --git a/stdlib/source/lux/compiler/default/phase/translation/scheme/function.jvm.lux b/stdlib/source/lux/compiler/default/phase/translation/scheme/function.jvm.lux
index d4316a0b5..7eeb5a8ed 100644
--- a/stdlib/source/lux/compiler/default/phase/translation/scheme/function.jvm.lux
+++ b/stdlib/source/lux/compiler/default/phase/translation/scheme/function.jvm.lux
@@ -71,7 +71,7 @@
                                       (_.let (list [@num-args (_.length/1 @curried)])
                                         (<| (_.if (|> @num-args (_.=/2 arityO))
                                               (<| (_.let (list [(reference.local' 0) @function]))
-                                                  (_.let-values (list [[(|> (list.n/range 0 (dec arity))
+                                                  (_.let-values (list [[(|> (list.indices arity)
                                                                             (list/map ..input))
                                                                         #.None]
                                                                        (_.apply/2 (_.global "apply") (_.global "values") @curried)]))
diff --git a/stdlib/source/lux/compiler/default/repl/type.lux b/stdlib/source/lux/compiler/default/repl/type.lux
index 212c5bcb9..7d3ac0d9c 100644
--- a/stdlib/source/lux/compiler/default/repl/type.lux
+++ b/stdlib/source/lux/compiler/default/repl/type.lux
@@ -110,7 +110,7 @@
                  (n/= num-tags (list.size casesR+)))]
     (wrap (function (_ variantV)
             (loop [cases-left (list.zip3 tags
-                                         (list.n/range 0 (dec num-tags))
+                                         (list.indices num-tags)
                                          casesR+)
                    variantV variantV]
               (case cases-left
diff --git a/stdlib/source/lux/concurrency/actor.lux b/stdlib/source/lux/concurrency/actor.lux
index f6a6fbe0d..a9154877e 100644
--- a/stdlib/source/lux/concurrency/actor.lux
+++ b/stdlib/source/lux/concurrency/actor.lux
@@ -334,12 +334,10 @@
              g!actor-refs (: (List Code)
                              (if (list.empty? actor-vars)
                                (list)
-                               (|> actor-vars list.size dec
-                                   (list.n/range 0) (list/map (|>> code.nat (~) ($) (`))))))
+                               (|> actor-vars list.size list.indices (list/map (|>> code.nat (~) ($) (`))))))
              ref-replacements (|> (if (list.empty? actor-vars)
                                     (list)
-                                    (|> actor-vars list.size dec
-                                        (list.n/range 0) (list/map (|>> code.nat (~) ($) (`)))))
+                                    (|> actor-vars list.size list.indices (list/map (|>> code.nat (~) ($) (`)))))
                                   (: (List Code))
                                   (list.zip2 g!all-vars)
                                   (: (List [Code Code])))
diff --git a/stdlib/source/lux/data/collection/array.lux b/stdlib/source/lux/data/collection/array.lux
index 09fe50412..f19ad6547 100644
--- a/stdlib/source/lux/data/collection/array.lux
+++ b/stdlib/source/lux/data/collection/array.lux
@@ -62,7 +62,7 @@
                    (#.Some value)
                    (write (n/+ offset dest-start) value target)))
                dest-array
-               (list.n/range 0 (dec length)))))
+               (list.indices length))))
 
 (def: #export (occupied array)
   {#.doc "Finds out how many cells in an array are occupied."}
@@ -82,7 +82,7 @@
   (All [a] (-> (Array a) Nat))
   (n/- (occupied array) (size array)))
 
-(def: #export (filter p xs)
+(def: #export (filter! p xs)
   (All [a]
     (-> (-> a Bit) (Array a) (Array a)))
   (list/fold (function (_ idx xs')
@@ -184,7 +184,7 @@
                                _
                                #0)))
                       #1
-                      (list.n/range 0 (dec sxs)))))
+                      (list.indices sxs))))
     ))
 
 (structure: #export Monoid<Array> (All [a] (Monoid (Array a)))
@@ -210,7 +210,7 @@
                        (#.Some x)
                        (write idx (f x) mb)))
                    (new arr-size)
-                   (list.n/range 0 (dec arr-size)))
+                   (list.indices arr-size))
         ))))
 
 (structure: #export _ (Fold Array)
diff --git a/stdlib/source/lux/data/collection/dictionary.lux b/stdlib/source/lux/data/collection/dictionary.lux
index 3d4e84207..f48554f55 100644
--- a/stdlib/source/lux/data/collection/dictionary.lux
+++ b/stdlib/source/lux/data/collection/dictionary.lux
@@ -146,11 +146,6 @@
         (array.copy idx 0 array 0)
         (array.copy (n/- idx new-size) (inc idx) array idx))))
 
-## Given a top-limit for indices, produces all indices in [0, R).
-(def: indices-for
-  (-> Nat (List Index))
-  (|>> dec (list.n/range 0)))
-
 ## Increases the level-shift by the branching-exponent, to explore
 ## levels further down the tree.
 (def: level-up
@@ -240,7 +235,7 @@
 
 ## When #Base nodes grow too large, they're promoted to #Hierarchy to
 ## add some depth to the tree and help keep it's balance.
-(def: hierarchy-indices (List Index) (indices-for hierarchy-nodes-size))
+(def: hierarchy-indices (List Index) (list.indices hierarchy-nodes-size))
 
 (def: (promote-base put' Hash<k> level bitmap base)
   (All [k v]
diff --git a/stdlib/source/lux/data/collection/list.lux b/stdlib/source/lux/data/collection/list.lux
index bbc649fb9..d11f0a080 100644
--- a/stdlib/source/lux/data/collection/list.lux
+++ b/stdlib/source/lux/data/collection/list.lux
@@ -379,6 +379,13 @@
   [tail (List a) xs' "For a list of size N, returns the N-1 elements after the first one."]
   )
 
+(def: #export (indices size)
+  {#.doc "Produces all the valid indices for a given size."}
+  (All [a] (-> Nat (List Nat)))
+  (if (n/= 0 size)
+    (list)
+    (|> size dec (n/range 0))))
+
 ## [Syntax]
 (def: (identifier$ name)
   (-> Text Code)
@@ -415,7 +422,7 @@
     (^ (list [_ (#.Nat num-lists)]))
     (if (n/> 0 num-lists)
       (let [(^open ".") Functor<List>
-            indices (n/range 0 (dec num-lists))
+            indices (..indices num-lists)
             type-vars (: (List Code) (map (|>> nat/encode identifier$) indices))
             zip-type (` (All [(~+ type-vars)]
                           (-> (~+ (map (: (-> Code Code) (function (_ var) (` (List (~ var)))))
@@ -459,7 +466,7 @@
     (^ (list [_ (#.Nat num-lists)]))
     (if (n/> 0 num-lists)
       (let [(^open ".") Functor<List>
-            indices (n/range 0 (dec num-lists))
+            indices (..indices num-lists)
             g!return-type (identifier$ "\treturn-type\t")
             g!func (identifier$ "\tfunc\t")
             type-vars (: (List Code) (map (|>> nat/encode identifier$) indices))
@@ -568,10 +575,3 @@
   {#.doc "Pairs every element in the list with its index, starting at 0."}
   (All [a] (-> (List a) (List [Nat a])))
   (enumerate' 0 xs))
-
-(def: #export (indices size)
-  {#.doc "Produces all the valid indices for a given size."}
-  (All [a] (-> Nat (List Nat)))
-  (if (n/= 0 size)
-    (list)
-    (|> size dec (n/range 0))))
diff --git a/stdlib/source/lux/data/color.lux b/stdlib/source/lux/data/color.lux
index e070ced40..335b937dd 100644
--- a/stdlib/source/lux/data/color.lux
+++ b/stdlib/source/lux/data/color.lux
@@ -291,7 +291,7 @@
                   (from-hsl [(|> idx .int int-to-frac (f/* slice) (f/+ hue) normalize)
                              saturation
                              luminance]))
-                (list.n/range 0 (dec results))))))
+                (list.indices results)))))
 
 (def: #export (monochromatic results color)
   (-> Nat Color (List Color))
@@ -299,7 +299,7 @@
     (list)
     (let [[hue saturation brightness] (to-hsb color)
           slice (|> +1.0 (f// (|> results .int int-to-frac)))]
-      (|> (list.n/range 0 (dec results))
+      (|> (list.indices results)
           (list/map (|>> .int int-to-frac
                          (f/* slice)
                          (f/+ brightness)
diff --git a/stdlib/source/lux/data/number/complex.lux b/stdlib/source/lux/data/number/complex.lux
index cd785fb31..aeefa03d6 100644
--- a/stdlib/source/lux/data/number/complex.lux
+++ b/stdlib/source/lux/data/number/complex.lux
@@ -297,7 +297,7 @@
           nth-root-of-abs (|> input abs (get@ #real) (math.pow (f// r-nth +1.0)))
           nth-phi (|> input argument (f// r-nth))
           slice (|> math.pi (f/* +2.0) (f// r-nth))]
-      (|> (list.n/range 0 (dec nth))
+      (|> (list.indices nth)
           (list/map (function (_ nth')
                       (let [inner (|> nth' .int int-to-frac
                                       (f/* slice)
diff --git a/stdlib/source/lux/macro/poly.lux b/stdlib/source/lux/macro/poly.lux
index 135cad97e..72a56b81d 100644
--- a/stdlib/source/lux/macro/poly.lux
+++ b/stdlib/source/lux/macro/poly.lux
@@ -192,7 +192,7 @@
                                   (let [partialI (|> current-arg (n/* 2) (n/+ funcI))
                                         partial-varI (inc partialI)
                                         partial-varL (label partial-varI)
-                                        partialC (` ((~ funcL) (~+ (|> (list.n/range 0 (dec num-args))
+                                        partialC (` ((~ funcL) (~+ (|> (list.indices num-args)
                                                                        (list/map (|>> (n/* 2) inc (n/+ funcI) label))
                                                                        list.reverse))))]
                                     (recur (inc current-arg)
diff --git a/stdlib/source/lux/macro/poly/equivalence.lux b/stdlib/source/lux/macro/poly/equivalence.lux
index af714ed51..672817ee6 100644
--- a/stdlib/source/lux/macro/poly/equivalence.lux
+++ b/stdlib/source/lux/macro/poly/equivalence.lux
@@ -116,7 +116,7 @@
             (do @
               [g!eqs (poly.tuple (p.many Equivalence<?>))
                #let [g!_ (code.local-identifier "_____________")
-                     indices (|> (list.size g!eqs) dec (list.n/range 0))
+                     indices (list.indices (list.size g!eqs))
                      g!lefts (list/map (|>> nat/encode (text/compose "left") code.local-identifier) indices)
                      g!rights (list/map (|>> nat/encode (text/compose "right") code.local-identifier) indices)]]
               (wrap (` (: (~ (@Equivalence inputT))
diff --git a/stdlib/source/lux/macro/poly/functor.lux b/stdlib/source/lux/macro/poly/functor.lux
index 205e78566..d866db45c 100644
--- a/stdlib/source/lux/macro/poly/functor.lux
+++ b/stdlib/source/lux/macro/poly/functor.lux
@@ -74,8 +74,8 @@
                                     outL (code.local-identifier "____________outL")]
                               [inT+ outC] (poly.function (p.many poly.any)
                                             (Arg<?> outL))
-                              #let [inC+ (|> (list.size inT+) dec
-                                             (list.n/range 0)
+                              #let [inC+ (|> (list.size inT+)
+                                             list.indices
                                              (list/map (|>> %n (format "____________inC") code.local-identifier)))]]
                              (wrap (` (function ((~ g!) (~+ inC+))
                                         (let [(~ outL) ((~ valueC) (~+ inC+))]
diff --git a/stdlib/source/lux/macro/poly/json.lux b/stdlib/source/lux/macro/poly/json.lux
index 9eabdc816..f1a5a840a 100644
--- a/stdlib/source/lux/macro/poly/json.lux
+++ b/stdlib/source/lux/macro/poly/json.lux
@@ -163,8 +163,8 @@
           (do @
             [g!encoders (poly.tuple (p.many Codec<JSON,?>//encode))
              #let [g!_ (code.local-identifier "_______")
-                   g!members (|> (list.size g!encoders) dec
-                                 (list.n/range 0)
+                   g!members (|> (list.size g!encoders)
+                                 list.indices
                                  (list/map (|>> nat/encode code.local-identifier)))]]
             (wrap (` (: (~ (@JSON//encode inputT))
                         (function ((~ g!_) [(~+ g!members)])
diff --git a/stdlib/source/lux/math/random.lux b/stdlib/source/lux/math/random.lux
index 826846aac..f743b2d35 100644
--- a/stdlib/source/lux/math/random.lux
+++ b/stdlib/source/lux/math/random.lux
@@ -313,7 +313,7 @@
                                  [rand nat]
                                  (wrap (swap idx (n/% _size rand) vec))))
                              row
-                             (list.n/range 0 (dec _size)))]
+                             (list.indices _size))]
     (|> _shuffle
         (run (pcg-32 [123 seed]))
         product.right)))
diff --git a/stdlib/source/lux/type/implicit.lux b/stdlib/source/lux/type/implicit.lux
index 6f26a01f8..42db42900 100644
--- a/stdlib/source/lux/type/implicit.lux
+++ b/stdlib/source/lux/type/implicit.lux
@@ -326,10 +326,10 @@
               (::: eq.= x y)
               "(List Nat) equivalence"
               (::: =
-                (list.n/range 1 10)
-                (list.n/range 1 10))
+                (list.indices 10)
+                (list.indices 10))
               "(Functor List) map"
-              (::: map inc (list.n/range 0 9))
+              (::: map inc (list.indices 10))
               "Caveat emptor: You need to make sure to import the module of any structure you want to use."
               "Otherwise, this macro will not find it.")}
   (case args
diff --git a/stdlib/test/test/lux/data/collection/array.lux b/stdlib/test/test/lux/data/collection/array.lux
index ac3061464..f1421f7ea 100644
--- a/stdlib/test/test/lux/data/collection/array.lux
+++ b/stdlib/test/test/lux/data/collection/array.lux
@@ -73,7 +73,7 @@
                   (and (n/= size (@.occupied array))
                        (n/= 0 (@.vacant array))))
             (test "Filtering mutates the array to remove invalid values."
-                  (exec (@.filter n/even? array)
+                  (exec (@.filter! n/even? array)
                     (and (n/< size (@.occupied array))
                          (n/> 0 (@.vacant array))
                          (n/= size (n/+ (@.occupied array)