Improvements and fixes to "tuple//left" and "tuple//right".

7 files changed, 116 insertions, 96 deletions

diff --git a/stdlib/source/lux/data/text/regex.lux b/stdlib/source/lux/data/text/regex.lux
index 5e867b9b6..73b6dab3b 100644
--- a/stdlib/source/lux/data/text/regex.lux
+++ b/stdlib/source/lux/data/text/regex.lux
@@ -360,17 +360,15 @@
   (do p.monad
     [#let [sub^ (re-sequential^ capturing? re-scoped^ current-module)]
      head sub^
-     tail (p.some (p.after (l.this "|") sub^))
-     #let [g!op (code.identifier ["" " alt "])]]
+     tail (p.some (p.after (l.this "|") sub^))]
     (if (list.empty? tail)
       (wrap head)
       (wrap [(list@fold n/max (product.left head) (list@map product.left tail))
-             (` (let [(~ g!op) (~ (if capturing?
-                                    (` (~! |||^))
-                                    (` (~! |||_^))))]
-                  ($_ (~ g!op)
-                      (~ (prep-alternative head))
-                      (~+ (list@map prep-alternative tail)))))]))))
+             (` ($_ ((~ (if capturing?
+                          (` (~! |||^))
+                          (` (~! |||_^)))))
+                    (~ (prep-alternative head))
+                    (~+ (list@map prep-alternative tail))))]))))
 
 (def: (re-scoped^ current-module)
   (-> Text (l.Lexer [Re-Group Code]))
diff --git a/stdlib/source/lux/tool/compiler/phase/generation/js/runtime.lux b/stdlib/source/lux/tool/compiler/phase/generation/js/runtime.lux
index f492479d4..8908c3335 100644
--- a/stdlib/source/lux/tool/compiler/phase/generation/js/runtime.lux
+++ b/stdlib/source/lux/tool/compiler/phase/generation/js/runtime.lux
@@ -177,30 +177,33 @@
       @lux//program-args
       ))
 
-(runtime: (tuple//left lefts tuple)
-  (with-vars [last-index-right]
-    ($_ _.then
-        (_.define last-index-right (..last-index tuple))
-        (_.if (_.> lefts last-index-right)
-          ## No need for recursion
-          (_.return (_.at lefts tuple))
-          ## Needs recursion
-          (_.return (tuple//left (_.- last-index-right lefts)
-                                 (_.at last-index-right tuple)))))))
-
-(runtime: (tuple//right lefts tuple)
-  (with-vars [last-index-right right-index]
-    ($_ _.then
-        (_.define last-index-right (..last-index tuple))
-        (_.define right-index (_.+ (_.i32 +1) lefts))
-        (_.cond (list [(_.= right-index last-index-right)
-                       (_.return (_.at right-index tuple))]
-                      [(_.> right-index last-index-right)
-                       ## Needs recursion.
-                       (_.return (tuple//right (_.- last-index-right lefts)
-                                               (_.at last-index-right tuple)))])
-                (_.return (_.do "slice" (list right-index) tuple)))
-        )))
+(with-expansions [<recur> (as-is ($_ _.then
+                                     (_.set lefts (_.- last-index-right lefts))
+                                     (_.set tuple (_.at last-index-right tuple))))]
+  (runtime: (tuple//left lefts tuple)
+    (with-vars [last-index-right]
+      (<| (_.while (_.boolean true))
+          ($_ _.then
+              (_.define last-index-right (..last-index tuple))
+              (_.if (_.> lefts last-index-right)
+                ## No need for recursion
+                (_.return (_.at lefts tuple))
+                ## Needs recursion
+                <recur>)))))
+
+  (runtime: (tuple//right lefts tuple)
+    (with-vars [last-index-right right-index]
+      (<| (_.while (_.boolean true))
+          ($_ _.then
+              (_.define last-index-right (..last-index tuple))
+              (_.define right-index (_.+ (_.i32 +1) lefts))
+              (_.cond (list [(_.= right-index last-index-right)
+                             (_.return (_.at right-index tuple))]
+                            [(_.> right-index last-index-right)
+                             ## Needs recursion.
+                             <recur>])
+                      (_.return (_.do "slice" (list right-index) tuple)))
+              )))))
 
 (runtime: (sum//get sum wants-last wanted-tag)
   (let [no-match! (_.return _.null)
diff --git a/stdlib/source/lux/tool/compiler/phase/generation/lua/runtime.lux b/stdlib/source/lux/tool/compiler/phase/generation/lua/runtime.lux
index 5e45682d1..648d35d32 100644
--- a/stdlib/source/lux/tool/compiler/phase/generation/lua/runtime.lux
+++ b/stdlib/source/lux/tool/compiler/phase/generation/lua/runtime.lux
@@ -137,6 +137,9 @@
 
 (def: last-index (|>> _.length (_.- (_.int +1))))
 
+## No need to turn tuple//left and tuple//right into loops, as Lua
+## does tail-call optimization.
+## https://www.lua.org/pil/6.3.html
 (runtime: (tuple//left lefts tuple)
   (with-vars [last-right]
     ($_ _.then
diff --git a/stdlib/source/lux/tool/compiler/phase/generation/python/runtime.lux b/stdlib/source/lux/tool/compiler/phase/generation/python/runtime.lux
index bdb0a8d2b..896b9e18a 100644
--- a/stdlib/source/lux/tool/compiler/phase/generation/python/runtime.lux
+++ b/stdlib/source/lux/tool/compiler/phase/generation/python/runtime.lux
@@ -183,30 +183,33 @@
 (def: last-index
   (|>> _.len/1 (_.- (_.int +1))))
 
-(runtime: (tuple//left lefts tuple)
-  (with-vars [last-index-right]
-    ($_ _.then
-        (_.set (list last-index-right) (..last-index tuple))
-        (_.if (_.> lefts last-index-right)
-          ## No need for recursion
-          (_.return (_.nth lefts tuple))
-          ## Needs recursion
-          (_.return (tuple//left (_.- last-index-right lefts)
-                                 (_.nth last-index-right tuple)))))))
-
-(runtime: (tuple//right lefts tuple)
-  (with-vars [last-index-right right-index]
-    ($_ _.then
-        (_.set (list last-index-right) (..last-index tuple))
-        (_.set (list right-index) (_.+ (_.int +1) lefts))
-        (_.cond (list [(_.= right-index last-index-right)
-                       (_.return (_.nth right-index tuple))]
-                      [(_.> right-index last-index-right)
-                       ## Needs recursion.
-                       (_.return (tuple//right (_.- last-index-right lefts)
-                                               (_.nth last-index-right tuple)))])
-                (_.return (_.slice-from right-index tuple)))
-        )))
+(with-expansions [<recur> (as-is ($_ _.then
+                                     (_.set (list lefts) (_.- last-index-right lefts))
+                                     (_.set (list tuple) (_.nth last-index-right tuple))))]
+  (runtime: (tuple//left lefts tuple)
+    (with-vars [last-index-right]
+      (<| (_.while (_.bool true))
+          ($_ _.then
+              (_.set (list last-index-right) (..last-index tuple))
+              (_.if (_.> lefts last-index-right)
+                ## No need for recursion
+                (_.return (_.nth lefts tuple))
+                ## Needs recursion
+                <recur>)))))
+
+  (runtime: (tuple//right lefts tuple)
+    (with-vars [last-index-right right-index]
+      (<| (_.while (_.bool true))
+          ($_ _.then
+              (_.set (list last-index-right) (..last-index tuple))
+              (_.set (list right-index) (_.+ (_.int +1) lefts))
+              (_.cond (list [(_.= right-index last-index-right)
+                             (_.return (_.nth right-index tuple))]
+                            [(_.> right-index last-index-right)
+                             ## Needs recursion.
+                             <recur>])
+                      (_.return (_.slice-from right-index tuple)))
+              )))))
 
 (runtime: (sum//get sum wantsLast wantedTag)
   (let [no-match! (_.return _.none)
diff --git a/stdlib/source/lux/tool/compiler/phase/generation/ruby/runtime.lux b/stdlib/source/lux/tool/compiler/phase/generation/ruby/runtime.lux
index e39e6af8e..71edc3e07 100644
--- a/stdlib/source/lux/tool/compiler/phase/generation/ruby/runtime.lux
+++ b/stdlib/source/lux/tool/compiler/phase/generation/ruby/runtime.lux
@@ -135,30 +135,33 @@
 (def: last-index
   (|>> ..tuple-size (_.- (_.int +1))))
 
-(runtime: (tuple//left lefts tuple)
-  (with-vars [last-index-right]
-    ($_ _.then
-        (_.set (list last-index-right) (..last-index tuple))
-        (_.if (_.> lefts last-index-right)
-          ## No need for recursion
-          (_.return (_.nth lefts tuple))
-          ## Needs recursion
-          (_.return (tuple//left (_.- last-index-right lefts)
-                                 (_.nth last-index-right tuple)))))))
-
-(runtime: (tuple//right lefts tuple)
-  (with-vars [last-index-right right-index]
-    ($_ _.then
-        (_.set (list last-index-right) (..last-index tuple))
-        (_.set (list right-index) (_.+ (_.int +1) lefts))
-        (_.cond (list [(_.= right-index last-index-right)
-                       (_.return (_.nth right-index tuple))]
-                      [(_.> right-index last-index-right)
-                       ## Needs recursion.
-                       (_.return (tuple//right (_.- last-index-right lefts)
-                                               (_.nth last-index-right tuple)))])
-                (_.return (_.array-range right-index (..tuple-size tuple) tuple)))
-        )))
+(with-expansions [<recur> (as-is ($_ _.then
+                                     (_.set (list lefts) (_.- last-index-right lefts))
+                                     (_.set (list tuple) (_.nth last-index-right tuple))))]
+  (runtime: (tuple//left lefts tuple)
+    (with-vars [last-index-right]
+      (<| (_.while (_.bool true))
+          ($_ _.then
+              (_.set (list last-index-right) (..last-index tuple))
+              (_.if (_.> lefts last-index-right)
+                ## No need for recursion
+                (_.return (_.nth lefts tuple))
+                ## Needs recursion
+                <recur>)))))
+
+  (runtime: (tuple//right lefts tuple)
+    (with-vars [last-index-right right-index]
+      (<| (_.while (_.bool true))
+          ($_ _.then
+              (_.set (list last-index-right) (..last-index tuple))
+              (_.set (list right-index) (_.+ (_.int +1) lefts))
+              (_.cond (list [(_.= right-index last-index-right)
+                             (_.return (_.nth right-index tuple))]
+                            [(_.> right-index last-index-right)
+                             ## Needs recursion.
+                             <recur>])
+                      (_.return (_.array-range right-index (..tuple-size tuple) tuple)))
+              )))))
 
 (runtime: (sum//get sum wantsLast wantedTag)
   (let [no-match! (_.return _.nil)
diff --git a/stdlib/source/test/lux.lux b/stdlib/source/test/lux.lux
index 21e529ecc..fa6a511d5 100644
--- a/stdlib/source/test/lux.lux
+++ b/stdlib/source/test/lux.lux
@@ -381,8 +381,6 @@
   (<| io
       _.run!
       (_.times 100)
-      ## (_.seed 16966479879996440699)
-      ## (_.seed 16140950815046933697)
       ## (_.seed 8804587020128699091)
       ## (_.seed 9353282359333487462)
       ..test))
diff --git a/stdlib/source/test/lux/data/text/regex.lux b/stdlib/source/test/lux/data/text/regex.lux
index 58ef21b8b..a683c446f 100644
--- a/stdlib/source/test/lux/data/text/regex.lux
+++ b/stdlib/source/test/lux/data/text/regex.lux
@@ -8,11 +8,12 @@
     ["p" parser]]
    [data
     [number (#+ hex)]
+    ["." error]
     ["." text ("#@." equivalence)
      ["." lexer (#+ Lexer)]]]
    [math
     ["r" random]]
-   [macro
+   ["." macro
     ["s" syntax (#+ syntax:)]]]
   {1
    ["." /]})
@@ -20,7 +21,7 @@
 (def: (should-pass regex input)
   (-> (Lexer Text) Text Bit)
   (|> (lexer.run input regex)
-      (case> (#.Right parsed)
+      (case> (#error.Success parsed)
              (text@= parsed input)
 
              _
@@ -29,24 +30,34 @@
 (def: (text-should-pass test regex input)
   (-> Text (Lexer Text) Text Bit)
   (|> (lexer.run input regex)
-      (case> (#.Right parsed)
+      (case> (#error.Success parsed)
              (text@= test parsed)
 
              _
-             #0)))
+             false)))
 
 (def: (should-fail regex input)
   (All [a] (-> (Lexer a) Text Bit))
   (|> (lexer.run input regex)
-      (case> (#.Left _) #1 _ #0)))
+      (case> (#error.Failure _)
+             true
+
+             _
+             false)))
 
 (syntax: (should-check pattern regex input)
-  (wrap (list (` (|> (lexer.run (~ input) (~ regex))
-                     (case> (^ (#.Right (~ pattern)))
-                            #1
+  (macro.with-gensyms [g!message g!_]
+    (wrap (list (` (|> (lexer.run (~ input) (~ regex))
+                       (case> (^ (#error.Success (~ pattern)))
+                              true
 
-                            (~' _)
-                            #0))))))
+                              (#error.Failure (~ g!message))
+                              (exec (log! (format "{{{Failure}}} " (~ g!message)))
+                                false)
+
+                              (~ g!_)
+                              (exec (log! (format "{{{Success}}} " "OH NO"))
+                                false))))))))
 
 (def: basics
   Test
@@ -177,7 +188,9 @@
   Test
   (let [number (/.regex "\d+")]
     (_.test "Can build complex regexs by combining simpler ones."
-            (should-check ["809-345-6789" "809" "345" "6789"] (/.regex "(\@<number>)-(\@<number>)-(\@<number>)") "809-345-6789"))))
+            (should-check ["809-345-6789" "809" "345" "6789"]
+                          (/.regex "(\@<number>)-(\@<number>)-(\@<number>)")
+                          "809-345-6789"))))
 
 (def: fuzzy-quantifiers
   Test
@@ -244,15 +257,14 @@
               (and (should-check ["a" (0 [])] (/.regex "a|b") "a")
                    (should-check ["b" (1 [])] (/.regex "a|b") "b")
                    (should-fail (/.regex "a|b") "c")))
-
       (_.test "Can have groups within alternations."
               (and (should-check ["abc" (0 ["b" "c"])] (/.regex "a(.)(.)|b(.)(.)") "abc")
                    (should-check ["bcd" (1 ["c" "d"])] (/.regex "a(.)(.)|b(.)(.)") "bcd")
                    (should-fail (/.regex "a(.)(.)|b(.)(.)") "cde")
 
-                   (should-check ["809-345-6789" (0 ["809" "345-6789" "345" "6789"])]
+                   (should-check ["123-456-7890" (0 ["123" "456-7890" "456" "7890"])]
                                  (/.regex "(\d{3})-((\d{3})-(\d{4}))|b(.)d")
-                                 "809-345-6789")))
+                                 "123-456-7890")))
       ))
 
 (def: pattern-matching