2 files changed, 45 insertions, 32 deletions

diff --git a/dot_config/nvim/fnl/toast/core.fnl b/dot_config/nvim/fnl/toast/core.fnl
index 54b0455..3c77e4a 100644
--- a/dot_config/nvim/fnl/toast/core.fnl
+++ b/dot_config/nvim/fnl/toast/core.fnl
@@ -12,6 +12,9 @@
    (each [i v (ipairs xs)]
     (when (> i n) (insert out v)))
    out))
+(fn empty? [xs]
+  "Returns true if the lengthable contains no elements."
+  (= 0 (length xs)))
 (fn first [xs]
   "The first element in a sequential table."
   (. xs 1))
@@ -21,27 +24,31 @@
 (fn group [n xs]
   "Group elements in xs in groups of n.
    Extra elements at the end will sit in the final group.
-   For example, (group 2 [1 2 3 4 5]) results in [[1 2] [3 4] [5]]."
-  (let [ll #(length (last $))
-        donext #(= (ll $) n)]
-   (accumulate [out [[]]
-                _ v (ipairs xs)]
-    (do (when (donext out)
-         (insert out []))
-        (insert (last out) v)
-        out))))
+   For example, (group 2 [1 2 3 4 5]) results in [[1 2] [3 4] [5]].
+   One exception is if xs is empty, in which case an empty collection is returned."
+ (if (empty? xs)
+   []
+   (let [ll #(length (last $))
+         donext #(= (ll $) n)]
+    (accumulate [out [[]]
+                 _ v (ipairs xs)]
+     (do (when (donext out)
+          (insert out []))
+         (insert (last out) v
+              out))))))
 (fn map [f xs]
   "Returns a sequential table consisting of the result of apply f to every item in xs."
   (accumulate [out []
                _ v (ipairs xs)]
    (let [mapped (f v)]
     (insert out (if (= 0 (select :# mapped))
-                     nil
-                     mapped)))))
+                    nil
+                    mapped)))))
 
 {: dec
  : inc
  : drop
+ : empty?
  : group
  : first
  : last}
diff --git a/dot_config/nvim/lua/toast/core.lua b/dot_config/nvim/lua/toast/core.lua
index c666faa..3313de7 100644
--- a/dot_config/nvim/lua/toast/core.lua
+++ b/dot_config/nvim/lua/toast/core.lua
@@ -17,6 +17,9 @@ local function drop(n, xs)
   end
   return out
 end
+local function empty_3f(xs)
+  return (0 == #xs)
+end
 local function first(xs)
   return xs[1]
 end
@@ -24,40 +27,43 @@ local function last(xs)
   return xs[#xs]
 end
 local function group(n, xs)
-  local ll
-  local function _3_(_241)
-    return #last(_241)
-  end
-  ll = _3_
-  local donext
-  local function _4_(_241)
-    return (ll(_241) == n)
-  end
-  donext = _4_
-  local out = {{}}
-  for _, v in ipairs(xs) do
-    if donext(out) then
-      insert(out, {})
-    else
+  if empty_3f(xs) then
+    return {}
+  else
+    local ll
+    local function _3_(_241)
+      return #last(_241)
     end
-    insert(last(out), v)
-    out = out
+    ll = _3_
+    local donext
+    local function _4_(_241)
+      return (ll(_241) == n)
+    end
+    donext = _4_
+    local out = {{}}
+    for _, v in ipairs(xs) do
+      if donext(out) then
+        insert(out, {})
+      else
+      end
+      out = insert(last(out), v, out)
+    end
+    return out
   end
-  return out
 end
 local function map(f, xs)
   local out = {}
   for _, v in ipairs(xs) do
     local mapped = f(v)
-    local function _6_()
+    local function _7_()
       if (0 == select("#", mapped)) then
         return nil
       else
         return mapped
       end
     end
-    out = insert(out, _6_())
+    out = insert(out, _7_())
   end
   return out
 end
-return {dec = dec, inc = inc, drop = drop, group = group, first = first, last = last}
+return {dec = dec, inc = inc, drop = drop, ["empty?"] = empty_3f, group = group, first = first, last = last}