diff --git a/spec.md b/spec.md
index 879d065..d045283 100644
--- a/spec.md
+++ b/spec.md
@@ -132,6 +132,11 @@ def example6-error(): Option[Unit] {
 }
 ```
 
+### pattern 1: labelled arguments
+```
+def [t] List.remove_prefix(prefix: List[t], list: 'from List[t])
+```
+
 ## automatic return types
 ```
 def add(a: Num, b: Num) -> _ {
@@ -181,7 +186,17 @@ def example(li: List[Char]) -> {t:Token,rem:List[Char]} {
 }
 ```
 
-## pattern 1: labelled arguments
+## recursive data types
 ```
-def [t] List.remove_prefix(prefix: List[t], list: 'from List[t])
+type List[t] = {head:t, tail:List[t]}
+# now you might notice an issue with this
+# `type` defines non-distinct type alisases
+# so what is the type of this...
+# Introducing: type self references
+# the above example is the same as this:
+type List[t] = &a {head:t, tail:a}
+
+# example 2:
+# a List[List[t]] is just:
+&b {head: &a {head:t, tail:a}, tail: b}
 ```
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