From e4dbd341f5c1f89e4e498c099904f6f65a169ac1 Mon Sep 17 00:00:00 2001
From: Glenn Jackman <glenn.jackman@gmail.com>
Date: Tue, 24 Mar 2026 12:12:43 -0400
Subject: [PATCH] add `is_empty` to generator exported functions

---
 bin/generate-spec                                       | 6 ++++--
 exercises/practice/matching-brackets/.meta/example.moon | 4 ++--
 exercises/practice/proverb/.meta/spec_generator.moon    | 2 +-
 exercises/test_helpers.md                               | 9 +++++++++
 4 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/bin/generate-spec b/bin/generate-spec
index 83afdbf..2656bee 100755
--- a/bin/generate-spec
+++ b/bin/generate-spec
@@ -48,7 +48,7 @@ included_tests_from_toml = (path) ->
 
 -- ----------------------------------------------------------
 -- functions marked as global so spec_generators can see them
-export indent, quote, is_json_null
+export indent, quote, is_json_null, is_empty
 
 indent = (text, level) -> string.rep('  ', level) .. text
 
@@ -58,8 +58,10 @@ quote = (str) ->
   else
     "'#{str}'"
 
+is_empty = (t) -> not next t
+
 -- the dkjson `json.null` value is an empty table
-is_json_null = (value) -> type(value) == 'table' and #value == 0
+is_json_null = (value) -> type(value) == 'table' and is_empty(value)
 
 -- ----------------------------------------------------------
 
diff --git a/exercises/practice/matching-brackets/.meta/example.moon b/exercises/practice/matching-brackets/.meta/example.moon
index 23aa3f0..49e58fb 100644
--- a/exercises/practice/matching-brackets/.meta/example.moon
+++ b/exercises/practice/matching-brackets/.meta/example.moon
@@ -1,8 +1,8 @@
 push     = table.insert
 pop      = table.remove
-is_empty = (s) -> #s == 0
+is_empty = (t) -> not next t
 
-opener   = { [']']: '[', ['}']: '{', [')']: '(' }
+opener   = ']':'[', '}':'{', ')':'('
 
 
 {
diff --git a/exercises/practice/proverb/.meta/spec_generator.moon b/exercises/practice/proverb/.meta/spec_generator.moon
index cf4d812..8946ed7 100644
--- a/exercises/practice/proverb/.meta/spec_generator.moon
+++ b/exercises/practice/proverb/.meta/spec_generator.moon
@@ -4,7 +4,7 @@
   generate_test: (case, level) ->
     input = table.concat [quote word for word in *case.input.strings], ', '
     local expected
-    if #case.expected == 0
+    if is_empty case.expected
       expected = "''"
     else
       expected = "[[\n#{table.concat case.expected, '\n'}\n]]"
diff --git a/exercises/test_helpers.md b/exercises/test_helpers.md
index 3a6c6cc..9e2121a 100644
--- a/exercises/test_helpers.md
+++ b/exercises/test_helpers.md
@@ -1,5 +1,14 @@
 # Reusable stuff for spec generators
 
+## Functions in generate-spec script
+
+These functions are exported from generate-spec for use in spec_generator modules
+
+- `indent(text, level)` -- provide leading whitespace to the appropriate level.
+- `quote(str)` -- add quotation marks to the string, single or double as appropriate.
+- `is_empty(tbl)` -- predicate: is the table empty
+- `is_json_null(value)` -- predicate: is the value `json.null` from dkjson
+
 ## Helper functions
 
 Useful for generating pretty tables mostly.