diff --git a/egison.cabal b/egison.cabal
--- a/egison.cabal
+++ b/egison.cabal
@@ -1,5 +1,5 @@
 Name:                egison
-Version:             3.0.11
+Version:             3.0.12
 Synopsis:            The world's first language with non-linear pattern-matching against unfree data
 Description:         An interpreter for Egison, the world's first programming langugage which realized non-linear pattern-matching with unfree data types.
                      With Egison, you can represent pattern-matching with unfree data types intuitively,
@@ -19,6 +19,7 @@
 
 
 Data-files:          lib/core/base.egi lib/core/number.egi lib/core/collection.egi lib/core/pattern.egi
+                     lib/graph/graph.egi lib/tree/xml.egi lib/math/prime.egi
                      elisp/egison-mode.el
 
 Library
diff --git a/elisp/egison-mode.el b/elisp/egison-mode.el
--- a/elisp/egison-mode.el
+++ b/elisp/egison-mode.el
@@ -4,7 +4,7 @@
 
 ;;; Author: Satoshi Egi <egisatoshi@gmail.com>
 ;;; URL: https://github.com/egisatoshi/egison3/blob/master/elisp/egison-mode.el
-;;; Version: 0.1.4
+;;; Version: 0.1.5
 
 ;; Code goes here
 
diff --git a/hs-src/Language/Egison/Desugar.hs b/hs-src/Language/Egison/Desugar.hs
--- a/hs-src/Language/Egison/Desugar.hs
+++ b/hs-src/Language/Egison/Desugar.hs
@@ -104,7 +104,7 @@
   name <- fresh
   matcher' <- desugar matcher
   clauses' <- desugarMatchClauses clauses
-  desugar (LambdaExpr [name] (MatchExpr (VarExpr name) matcher' clauses'))
+  return $ LambdaExpr [name] (MatchExpr (VarExpr name) matcher' clauses')
 
 desugar (ArrayRefExpr (VarExpr name) (TupleExpr nums)) =
   desugar $ IndexedExpr (VarExpr name) nums
@@ -253,5 +253,5 @@
 desugarMatchClauses (clause:rest) = do
   clause' <- desugarMatchClause clause
   rest'   <- desugarMatchClauses rest
-  return $ clause : rest'
+  return $ clause' : rest'
 desugarMatchClauses [] = return []
diff --git a/lib/graph/graph.egi b/lib/graph/graph.egi
new file mode 100644
--- /dev/null
+++ b/lib/graph/graph.egi
@@ -0,0 +1,54 @@
+;;;
+;;; graph.egi
+;;;
+
+(define $graph
+  (lambda [$a]
+    (multiset (nodeInfo a))))
+
+(define $nodeInfo
+  (lambda [$a]
+    (algebraic-data-matcher
+      {<node a (multiset a) (multiset a)>})))
+
+(define $hamilton-cycle
+  (pattern-function [$a]
+    (& $g
+       <cons <node (& a_1 $h_1) <cons (& a_2 $h_2) _> _>
+             (loop $i (between 3 (size g))
+               <cons <node ,h_(- i 1) <cons (& a_i $h_i) _> _>
+                     ...>
+               <cons <node ,h_(size g) <cons ,h_1 _> _>
+                     <nil>>)>)))
+
+(define $hamilton-path
+  (pattern-function [$a]
+    (& $g
+       <cons <node (& a_1 $h_1) <cons (& a_2 $h_2) _> _>
+             (loop $i (between 3 (size g))
+               <cons <node ,h_(- i 1) <cons (& a_i $h_i) _> _>
+                     ...>
+               <cons <node ,h_(size g) _ _>
+                     <nil>>)>)))
+
+(define $hamilton-path2
+  (pattern-function [$a]
+    (& $g
+       (let {[$n (size g)]}
+         <cons <node (& a_1 $h_1) <cons (& a_2 $h_2) _> _>
+               (loop $i (between 3 n)
+                 <cons <node ,h_(- i 1) <cons (& a_i $h_i) _> _>
+                       ...>
+                 <cons <node ,h_n _ _>
+                       <nil>>)>)
+       )))
+
+(define $all-paths
+  (pattern-function [$s $e $p $rest]
+    (| <cons <node (& s p_1) <cons (& e p_2) _> _> rest>
+       <cons <node (& s p_1)  <cons (& p_2 $h_2) _> _>
+          (loop $i (from 2) ;; TEMPORARY
+            <cons <node ,h_(- i 1) <cons (& p_i $h_i) _> _>
+                  ...>
+            rest)>)))
+
diff --git a/lib/math/prime.egi b/lib/math/prime.egi
new file mode 100644
--- /dev/null
+++ b/lib/math/prime.egi
@@ -0,0 +1,12 @@
+(define $eratosthenes
+  (lambda [$n]
+    (let {[$ls (between 2 n)]}
+      (letrec {[$looper
+                (lambda [$ps $ls]
+                  (let {[$p (car ls)]
+                        [$xs (cdr ls)]}
+                    (if (gt? (* p p) (rac xs))
+                        {@ps @ls}
+                        (looper {@ps p} (filter (lambda [$l] (not (eq? (remainder l p) 0))) xs)))))
+                ]}
+        (looper {} ls)))))
diff --git a/lib/tree/xml.egi b/lib/tree/xml.egi
new file mode 100644
--- /dev/null
+++ b/lib/tree/xml.egi
@@ -0,0 +1,27 @@
+(define $xml
+  (matcher
+    {[,$val []
+      {[$tgt (match [val tgt] [xml xml]
+               {[[<leaf $tag $text> <leaf ,tag ,text>] {[]}]
+                [[<lnode $tag $xs> <lnode ,tag ,xs>] {[]}]
+                [[_ _] {}]})]}]
+     [<leaf $ $> [string string]
+      {[<Leaf $tag $text> {[tag text]}]
+       [_ {}]}]
+     [<lnode $ $> [string (list xml)] ; Node whose children are seen as a list.
+      {[<Node $tag $cs> {[tag cs]}]
+       [_ {}]}]
+     [<mnode $ $> [string (multiset xml)] ; Node whose children are seen as a multiset.
+      {[<Node $tag $cs> {[tag cs]}]
+       [_ {}]}]
+     [<descendant $> xml
+      {[$x {x @(all-descendants x)}]}]
+     [$ [something]
+      {[$tgt {tgt}]}]
+     }))
+
+(define $all-descendants
+  (lambda [$x]
+    (match x xml
+      {[<leaf _ _> {}]
+       [<lnode _ $cs> {@cs @(concat (map all-descendants cs))}]})))