fix for substituting Nothing into interpolated text, and other tweaks

src/core/gossamer-core.scala

@@ -141,8 +141,6 @@ extension [TextType: Textual](text: TextType)
   def capitalize: TextType = TextType.concat(text.keep(1).upper, text.after(Prim))
   def uncapitalize: TextType = TextType.concat(text.keep(1).lower, text.after(Prim))
 
-  inline def head: Char = TextType.unsafeChar(text, Prim)
-  inline def last: Char = TextType.unsafeChar(text, Ult.of(text))
   inline def tail: TextType = text.skip(1, Ltr)
   inline def init: TextType = text.skip(1, Rtl)
   inline def empty: Boolean = text.length == 0

src/core/gossamer.Buffer.scala

@@ -32,3 +32,5 @@ abstract class Buffer[TextType](size: Optional[Int] = Unset):
 
   def apply(): TextType = result()
   def clear(): this.type = this.also(wipe())
+  def empty: Boolean = length == 0
+  def length: Int

src/core/gossamer.Interpolation.scala

@@ -31,6 +31,7 @@ object Interpolation:
   case class Input(txt: Text)
 
   given [ValueType: Showable] => Insertion[Input, ValueType] = value => Input(value.show)
+  given Insertion[Input, Nothing] = value => Input("".tt)
 
   object T extends Interpolator[Input, Text, Text]:
     def initial: Text = anticipation.Text("")

src/core/gossamer.TextBuffer.scala

@@ -22,5 +22,7 @@ import vacuous.*
 class TextBuffer(size: Optional[Int] = Unset) extends Buffer[Text](size):
   private val buffer: StringBuilder = size.lay(StringBuilder())(StringBuilder(_))
   protected def put(text: Text): Unit = buffer.append(text)
+  def put(char: Char): Unit = buffer.append(char)
   protected def wipe(): Unit = buffer.clear()
   protected def result(): Text = buffer.toString().tt
+  def length: Int = buffer.length

src/core/soundness+gossamer-core.scala

@@ -19,11 +19,11 @@ package soundness
 export gossamer.{Bidi, Buffer, Cuttable, Decimalizer, Interpolation, Joinable, Numerous,
     Presentational, Pue, RangeError, TextBuffer, Textual, append, construct, fill, txt, t, utf8,
     utf16, ascii, hex, text, pue, cut, pascal, camel, snake, kebab, length, populated, lower,
-    upper, plain, skip, keep, capitalize, uncapitalize, head, last, tail, init, empty, chars,
+    upper, plain, skip, keep, capitalize, uncapitalize, tail, init, empty, chars,
     slice, snip, reverse, contains, trim, where, upto, dropWhile, snipWhere,
     mapChars, count, metrics, pad, center, fit, uncamel, unkebab, unsnake, starts, ends,
     tr, subscript, superscript, rsub, sub, flatMap, urlEncode, urlDecode, punycode, bytes,
-    sysBytes, lev, join, add}
+    sysBytes, lev, join, add, words, lines}
 
 package decimalFormatters:
   export gossamer.decimalFormatters.java