further improvements for term rewriting macros

tests/patterns/targlist.nim

@@ -0,0 +1,9 @@
+discard """
+  output: "12false3ha"
+"""
+
+proc f(x: varargs[string, `$`]) = nil
+template optF{f(X)}(x: varargs[expr]) = 
+  writeln(stdout, x)
+
+f 1, 2, false, 3, "ha"

tests/patterns/tor.nim

@@ -0,0 +1,9 @@
+discard """
+  output: "110"
+"""
+
+template arithOps: expr = (`+` | `-` | `*`)
+template testOr{ (arithOps{f})(a, b) }(a, b, f: expr): expr = f(a+1, b)
+
+let xx = 10
+echo 10*xx

tests/patterns/tstar.nim

@@ -0,0 +1,19 @@
+discard """
+  output: "my awesome concat"
+"""
+
+var
+  calls = 0
+  
+proc `&&`(s: varargs[string]): string =
+  result = s[0]
+  for i in 1..len(s)-1: result.add s[i]
+  inc calls
+
+template optConc{ `&&` * a }(a: expr): expr = &&a
+
+let space = " "
+echo "my" && (space & "awe" && "some " ) && "concat"
+
+# check that it's been properly optimized:
+doAssert calls == 1

tests/patterns/tstmtlist.nim

@@ -0,0 +1,18 @@
+discard """
+  output: '''0
+|12|34
+'''
+"""
+
+template optWrite{
+  write(stdout, x)
+  write(stdout, y)
+}(x, y: string) =
+  write(stdout, "|", x, y, "|")
+
+if true:
+  echo "0"
+  write stdout, "1"
+  write stdout, "2"
+  write stdout, "3"
+  echo "4"