diff --git a/TODO.md b/TODO.md
index 91a9636a..0e1db41e 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,8 +1,8 @@
-[syntax] use "@cicada-lang/partech" to implement new syntax
+`"head" let` instead of `(let head)`
 
 `Node` with optionally named port
 
-- `NetRenderer` show free port names
+`defnode` instead of `defcons` and `defelim`
 
 `NetRenderer` -- format to simple text representation of graph
 
@@ -12,6 +12,8 @@ change the `render` command to simple `run` command
 
 [maybe] quit using `ActiveEdge`
 
+`NetRenderer` show free port names
+
 # the paper
 
 phase space and monoid -- understand the model theory of linear logic
diff --git a/docs/notes/design-of-new-syntax.md b/docs/notes/design-of-new-syntax.md
index 61975ad5..3bed276a 100644
--- a/docs/notes/design-of-new-syntax.md
+++ b/docs/notes/design-of-new-syntax.md
@@ -59,13 +59,12 @@ defrule add1 add
 end
 ```
 
-`defn` is a short hand for simple `defrule`,
-to define rules that works like a function.
+`defru` is a short hand for simple `defrule`.
 
 ```inet
-defn zero add end
+defru zero add end
 
-defn add1 add add add1 end
+defru add1 add add add1 end
 ```
 
 ```inet
@@ -111,12 +110,12 @@ defrule cons append
   return-(append)
 end
 
-defn null append end
+defru null append end
 
 # the syntax for `let` and `get` is yet to be designed.
 # I use `<...>` and description for work-in-progress syntax design.
 
-defn cons append
+defru cons append
   <let head> append <get head> cons
 end
 
@@ -158,13 +157,13 @@ defrule diff diff_open
   (diff)-left return-(diff_open)
 end
 
-defn diff diff_append
+defru diff diff_append
   <let diff_list end start>
   <get end> <get diff_list>
   diff_open <get start> diff
 end
 
-defn diff diff_open
+defru diff diff_open
   <let list end start>
   <get list> <get end> connect
   <get start>
diff --git a/docs/tests/diff-list.inet b/docs/tests/diff-list.inet
index fb80a6cb..a065a31a 100644
--- a/docs/tests/diff-list.inet
+++ b/docs/tests/diff-list.inet
@@ -1,29 +1,33 @@
-(defcons sole 0 1)
+defcons sole 0 1 end
 
-(defcons null 0 1)
-(defcons cons 2 1)
+defcons null 0 1 end
+defcons cons 2 1 end
 
-(defcons diff 2 1)
+defcons diff 2 1 end
 
-(defelim diff-append 2 1)
+defelim diff_append 2 1 end
 
-(defrule (diff diff-append)
-  (let diff-list end start)
-  end diff-list diff-open start diff)
+defru diff diff_append
+  (let start) (let fin) (let diff_list)
+  fin diff_list diff_open start diff
+end
 
-(defelim diff-open 2 1)
+defelim diff_open 2 1 end
 
-(defrule (diff diff-open)
-  (let list end start)
-  list end connect
-  start)
+defru diff diff_open
+  (let start) (let fin) (let list)
+  list fin connect
+  start
+end
 
-(defnet one-two-soles
+defnet one_two_soles
   wire sole cons diff
   wire sole cons sole cons diff
-  diff-append)
+  diff_append
+end
 
-(defnet two-two-soles
+defnet two_two_soles
   wire sole cons sole cons diff
   wire sole cons sole cons diff
-  diff-append)
+  diff_append
+end
diff --git a/docs/tests/diff-list.inet.one-two-soles.finial.txt b/docs/tests/diff-list.inet.one_two_soles.finial.txt
similarity index 100%
rename from docs/tests/diff-list.inet.one-two-soles.finial.txt
rename to docs/tests/diff-list.inet.one_two_soles.finial.txt
diff --git a/docs/tests/diff-list.inet.one-two-soles.initial.txt b/docs/tests/diff-list.inet.one_two_soles.initial.txt
similarity index 66%
rename from docs/tests/diff-list.inet.one-two-soles.initial.txt
rename to docs/tests/diff-list.inet.one_two_soles.initial.txt
index eb6166c3..1465870c 100644
--- a/docs/tests/diff-list.inet.one-two-soles.initial.txt
+++ b/docs/tests/diff-list.inet.one_two_soles.initial.txt
@@ -16,18 +16,18 @@ cons#8
 diff#9 -- cons#8 [label="0-2"]
 cons#8
 diff#9
-diff-append#10 -- diff#3 [label="1-2"]
+diff_append#10 -- diff#3 [label="1-2"]
 diff#3
-diff-append#10
+diff_append#10
 cons#2 -- diff#3 [label="1-1"]
 diff#3
 cons#2
 cons#6 -- diff#9 [label="1-1"]
 diff#9
 cons#6
-diff-append#10 -- diff#9 [label="0-2" color=red]
+diff_append#10 -- diff#9 [label="0-2" color=red]
 diff#9
-diff-append#10
-diff-append#10(2) -- diff-append#10
-diff-append#10
-diff-append#10(2)
\ No newline at end of file
+diff_append#10
+diff_append#10(2) -- diff_append#10
+diff_append#10
+diff_append#10(2)
\ No newline at end of file
diff --git a/docs/tests/diff-list.inet.two-two-soles.finial.txt b/docs/tests/diff-list.inet.two_two_soles.finial.txt
similarity index 100%
rename from docs/tests/diff-list.inet.two-two-soles.finial.txt
rename to docs/tests/diff-list.inet.two_two_soles.finial.txt
diff --git a/docs/tests/diff-list.inet.two-two-soles.initial.txt b/docs/tests/diff-list.inet.two_two_soles.initial.txt
similarity index 72%
rename from docs/tests/diff-list.inet.two-two-soles.initial.txt
rename to docs/tests/diff-list.inet.two_two_soles.initial.txt
index 19ac3460..3425c168 100644
--- a/docs/tests/diff-list.inet.two-two-soles.initial.txt
+++ b/docs/tests/diff-list.inet.two_two_soles.initial.txt
@@ -22,18 +22,18 @@ cons#24
 diff#25 -- cons#24 [label="0-2"]
 cons#24
 diff#25
-diff-append#26 -- diff#19 [label="1-2"]
+diff_append#26 -- diff#19 [label="1-2"]
 diff#19
-diff-append#26
+diff_append#26
 cons#16 -- diff#19 [label="1-1"]
 diff#19
 cons#16
 cons#22 -- diff#25 [label="1-1"]
 diff#25
 cons#22
-diff-append#26 -- diff#25 [label="0-2" color=red]
+diff_append#26 -- diff#25 [label="0-2" color=red]
 diff#25
-diff-append#26
-diff-append#26(2) -- diff-append#26
-diff-append#26
-diff-append#26(2)
\ No newline at end of file
+diff_append#26
+diff_append#26(2) -- diff_append#26
+diff_append#26
+diff_append#26(2)
\ No newline at end of file
diff --git a/docs/tests/list.inet b/docs/tests/list.inet
index 8c8c0fe9..4ad268f1 100644
--- a/docs/tests/list.inet
+++ b/docs/tests/list.inet
@@ -1,16 +1,17 @@
-(defcons sole 0 1)
+defcons sole 0 1 end
 
-(defcons null 0 1)
+defcons null 0 1 end
 
-(defcons cons 2 1)
+defcons cons 2 1 end
 
-(defelim append 2 1)
+defelim append 2 1 end
 
-(defrule (null append))
+defru null append end
 
-(defrule (cons append) (let head) append head cons)
+defru cons append (let head) append head cons end
 
-(defnet six-soles
+defnet six_soles
   null sole cons sole cons sole cons
   null sole cons sole cons sole cons
-  append)
+  append
+end
\ No newline at end of file
diff --git a/docs/tests/list.inet.six-soles.finial.txt b/docs/tests/list.inet.six_soles.finial.txt
similarity index 100%
rename from docs/tests/list.inet.six-soles.finial.txt
rename to docs/tests/list.inet.six_soles.finial.txt
diff --git a/docs/tests/list.inet.six-soles.initial.txt b/docs/tests/list.inet.six_soles.initial.txt
similarity index 100%
rename from docs/tests/list.inet.six-soles.initial.txt
rename to docs/tests/list.inet.six_soles.initial.txt
diff --git a/docs/tests/nat.inet b/docs/tests/nat.inet
index 4a9bf8f4..9471d6dd 100644
--- a/docs/tests/nat.inet
+++ b/docs/tests/nat.inet
@@ -1,17 +1,19 @@
-(defcons zero 0 1)
+defcons zero 0 1 end
 
-(defcons add1 1 1)
+defcons add1 1 1 end
 
-(defelim add 2 1)
+defelim add 2 1 end
 
-(defrule (zero add))
+defru zero add end
 
-(defrule (add1 add) add add1)
+defru add1 add add add1 end
 
-(defnet two
+defnet two
   zero add1
   zero add1
-  add)
+  add
+end
 
-(defnet four
-  two two add)
+defnet four
+  two two add
+end
\ No newline at end of file
diff --git a/docs/todo/diff-list.inet b/docs/todo/diff-list.inet
deleted file mode 100644
index 064aaf63..00000000
--- a/docs/todo/diff-list.inet
+++ /dev/null
@@ -1,33 +0,0 @@
-(defcons sole 0)
-
-(defcons null 0)
-(defcons cons 2)
-
-(defcons diff 2)
-
-(defelim diff-append 2)
-
-(defrule
-  (diff-append (diff start end) diff-list)
-  (diff start (diff-open diff-list end)))
-
-(defelim diff-open 2)
-
-(defrule
-  (diff-open (diff start end) list)
-  (connect end list)
-  start)
-
-(defnet one-two-soles
-  (let-wire x)
-  (let-wire y)
-  (diff-append
-   (diff (cons sole x) x)
-   (diff (cons sole (cons sole y)) y)))
-
-(defnet two-two-soles
-  (let-wire x)
-  (let-wire y)
-  (diff-append
-   (diff (cons sole (cons sole x)) x)
-   (diff (cons sole (cons sole y)) y)))
diff --git a/package-lock.json b/package-lock.json
index 0c367f2b..9949feef 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -9,7 +9,7 @@
       "version": "0.0.12",
       "license": "GPL-3.0-or-later",
       "dependencies": {
-        "@cicada-lang/sexp": "^0.0.36",
+        "@cicada-lang/partech": "^0.2.5",
         "@xieyuheng/command-line": "^0.0.10",
         "@xieyuheng/ty": "^0.1.22"
       },
@@ -24,13 +24,14 @@
         "typescript": "^5.1.6"
       }
     },
-    "node_modules/@cicada-lang/sexp": {
-      "version": "0.0.36",
-      "resolved": "https://registry.npmjs.org/@cicada-lang/sexp/-/sexp-0.0.36.tgz",
-      "integrity": "sha512-ogbz4SfwfkA8PRVmRcretSs3avN5QlsNPzuVghgchIyFQNI0Xs5T11MQsTuhIbQmW/uMd1WujeLCHn/IZ6D1zA==",
+    "node_modules/@cicada-lang/partech": {
+      "version": "0.2.5",
+      "resolved": "https://registry.npmjs.org/@cicada-lang/partech/-/partech-0.2.5.tgz",
+      "integrity": "sha512-Ns5L/tqbmlrkFOaG2I6NHkxmTR1hafH0WMQByEOvVAZ1kElMg0vHXvMbLwLaPqWsBz4qzT6kQ9fRKjIDDEUNyg==",
       "dependencies": {
         "fast-deep-equal": "^3.1.3",
-        "picocolors": "^1.0.0"
+        "picocolors": "^1.0.0",
+        "regexp-match-indices": "^1.0.2"
       }
     },
     "node_modules/@nodelib/fs.scandir": {
@@ -569,6 +570,22 @@
         "node": ">=0.12"
       }
     },
+    "node_modules/regexp-match-indices": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/regexp-match-indices/-/regexp-match-indices-1.0.2.tgz",
+      "integrity": "sha512-DwZuAkt8NF5mKwGGER1EGh2PRqyvhRhhLviH+R8y8dIuaQROlUfXjt4s9ZTXstIsSkptf06BSvwcEmmfheJJWQ==",
+      "dependencies": {
+        "regexp-tree": "^0.1.11"
+      }
+    },
+    "node_modules/regexp-tree": {
+      "version": "0.1.27",
+      "resolved": "https://registry.npmjs.org/regexp-tree/-/regexp-tree-0.1.27.tgz",
+      "integrity": "sha512-iETxpjK6YoRWJG5o6hXLwvjYAoW+FEZn9os0PD/b6AP6xQwsa/Y7lCVgIixBbUPMfhu+i2LtdeAqVTgGlQarfA==",
+      "bin": {
+        "regexp-tree": "bin/regexp-tree"
+      }
+    },
     "node_modules/require-from-string": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/require-from-string/-/require-from-string-2.0.2.tgz",
diff --git a/package.json b/package.json
index 6c23c475..ca20bd11 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
     "typescript": "^5.1.6"
   },
   "dependencies": {
-    "@cicada-lang/sexp": "^0.0.36",
+    "@cicada-lang/partech": "^0.2.5",
     "@xieyuheng/command-line": "^0.0.10",
     "@xieyuheng/ty": "^0.1.22"
   },
diff --git a/src/console/commands/RenderCommand.ts b/src/console/commands/RenderCommand.ts
index 41837874..455ebf26 100644
--- a/src/console/commands/RenderCommand.ts
+++ b/src/console/commands/RenderCommand.ts
@@ -1,4 +1,4 @@
-import { ParsingError } from "@cicada-lang/sexp/lib/errors"
+import { ParsingError } from "@cicada-lang/partech/lib/errors"
 import { Command, CommandRunner } from "@xieyuheng/command-line"
 import ty from "@xieyuheng/ty"
 import fs from "fs"
@@ -68,7 +68,7 @@ export class RenderCommand extends Command<Args, Opts> {
       }
     } catch (error) {
       if (error instanceof ParsingError) {
-        const report = error.span.report(text)
+        const report = error.report(text)
         console.error(report)
       }
 
diff --git a/src/lang/errors/ParsingError.ts b/src/lang/errors/ParsingError.ts
index 414a6083..379e6b6f 100644
--- a/src/lang/errors/ParsingError.ts
+++ b/src/lang/errors/ParsingError.ts
@@ -1 +1 @@
-export { ParsingError } from "@cicada-lang/sexp/lib/errors"
+export { ParsingError } from "@cicada-lang/partech/lib/errors"
diff --git a/src/lang/span/index.ts b/src/lang/span/index.ts
index 1a07a001..3c6037a3 100644
--- a/src/lang/span/index.ts
+++ b/src/lang/span/index.ts
@@ -1 +1 @@
-export { Span } from "@cicada-lang/sexp/lib/span"
+export { Span } from "@cicada-lang/partech/lib/span"
diff --git a/src/lang/syntax/Parser.ts b/src/lang/syntax/Parser.ts
deleted file mode 100644
index ef329f99..00000000
--- a/src/lang/syntax/Parser.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-import { Parser as SexpParser } from "@cicada-lang/sexp/lib/parser"
-import { Stmt } from "../stmt"
-import { matchStmt } from "./matchStmt"
-
-export class Parser extends SexpParser {
-  constructor() {
-    super({
-      quotes: [
-        { mark: "'", symbol: "quote" },
-        { mark: ",", symbol: "unquote" },
-        { mark: "`", symbol: "quasiquote" },
-      ],
-      parentheses: [
-        { start: "(", end: ")" },
-        { start: "[", end: "]" },
-      ],
-      comments: [";"],
-    })
-  }
-
-  parseStmts(text: string): Array<Stmt> {
-    return this.parseSexps(text).map(matchStmt)
-  }
-}
diff --git a/src/lang/syntax/grammars/index.ts b/src/lang/syntax/grammars/index.ts
new file mode 100644
index 00000000..6e51834e
--- /dev/null
+++ b/src/lang/syntax/grammars/index.ts
@@ -0,0 +1,10 @@
+import * as pt from "@cicada-lang/partech"
+
+export const zero_or_more = pt.grammars.zero_or_more
+export const one_or_more = pt.grammars.one_or_more
+export const optional = pt.grammars.optional
+export const dashline = pt.grammars.dashline
+
+export * from "./name"
+export * from "./stmt"
+export * from "./word"
diff --git a/src/lang/syntax/grammars/name.ts b/src/lang/syntax/grammars/name.ts
new file mode 100644
index 00000000..4f6a99e1
--- /dev/null
+++ b/src/lang/syntax/grammars/name.ts
@@ -0,0 +1,24 @@
+// NOTE Preserve keywords for JSON.
+
+const preserved = ["end"]
+
+export const variable_name = {
+  $pattern: [
+    "identifier",
+    `(^(?!(${preserved.join("|")})$)([_A-Za-z][_\\p{Letter}0-9]*))`,
+  ],
+}
+
+export const variable_names = {
+  $grammar: {
+    "variable_names:variable_names": [
+      {
+        variable_names: {
+          $ap: ["zero_or_more", "variable_name", '","'],
+        },
+      },
+      { last_name: "variable_name" },
+      { $ap: ["optional", '","'] },
+    ],
+  },
+}
diff --git a/src/lang/syntax/grammars/stmt.ts b/src/lang/syntax/grammars/stmt.ts
new file mode 100644
index 00000000..5312f7a5
--- /dev/null
+++ b/src/lang/syntax/grammars/stmt.ts
@@ -0,0 +1,37 @@
+export const stmt = {
+  $grammar: {
+    "stmt:defcons": [
+      '"defcons"',
+      { name: "variable_name" },
+      { inputArity: { $pattern: ["number"] } },
+      { outputArity: { $pattern: ["number"] } },
+      '"end"',
+    ],
+    "stmt:defelim": [
+      '"defelim"',
+      { name: "variable_name" },
+      { inputArity: { $pattern: ["number"] } },
+      { outputArity: { $pattern: ["number"] } },
+      '"end"',
+    ],
+    "stmt:defru": [
+      '"defru"',
+      { start: "variable_name" },
+      { end: "variable_name" },
+      { words: "words" },
+      '"end"',
+    ],
+    "stmt:defnet": [
+      '"defnet"',
+      { name: "variable_name" },
+      { words: "words" },
+      '"end"',
+    ],
+  },
+}
+
+export const stmts = {
+  $grammar: {
+    "stmts:stmts": [{ stmts: { $ap: ["zero_or_more", "stmt"] } }],
+  },
+}
diff --git a/src/lang/syntax/grammars/word.ts b/src/lang/syntax/grammars/word.ts
new file mode 100644
index 00000000..cc6019a9
--- /dev/null
+++ b/src/lang/syntax/grammars/word.ts
@@ -0,0 +1,12 @@
+export const word = {
+  $grammar: {
+    "word:call": [{ name: "variable_name" }],
+    "word:let": ['"("', '"let"', { name: "variable_name" }, '")"'],
+  },
+}
+
+export const words = {
+  $grammar: {
+    "words:words": [{ words: { $ap: ["zero_or_more", "word"] } }],
+  },
+}
diff --git a/src/lang/syntax/index.ts b/src/lang/syntax/index.ts
index e1edf1fb..9ec56324 100644
--- a/src/lang/syntax/index.ts
+++ b/src/lang/syntax/index.ts
@@ -1,8 +1,18 @@
-import { Stmt } from "../stmt"
-import { Parser } from "./Parser"
-import { matchStmt } from "./matchStmt"
-
-export function parseStmts(text: string): Array<Stmt> {
-  const parser = new Parser()
-  return parser.parseSexps(text).map(matchStmt)
-}
+import * as pt from "@cicada-lang/partech"
+import * as grammars from "./grammars"
+import * as matchers from "./matchers"
+
+/**
+
+   TODO We should use `camelCase` naming convention,
+   but "@cicada-lang/partech" is using `snake_case`,
+   we follow the library for now (will change eventually).
+
+**/
+
+export const parseStmts = pt.gen_parse({
+  preprocess: pt.preprocess.erase_comment,
+  lexer: pt.lexers.common,
+  grammar: pt.grammar_start(grammars, "stmts"),
+  matcher: matchers.stmts_matcher,
+})
diff --git a/src/lang/syntax/matchStmt.ts b/src/lang/syntax/matchStmt.ts
deleted file mode 100644
index aaaf5932..00000000
--- a/src/lang/syntax/matchStmt.ts
+++ /dev/null
@@ -1,66 +0,0 @@
-import {
-  match,
-  matchList,
-  matchNumber,
-  matchSymbol,
-} from "@cicada-lang/sexp/lib/match"
-import { list, v } from "@cicada-lang/sexp/lib/pattern-exp"
-import { Sexp } from "@cicada-lang/sexp/lib/sexp"
-import { Stmt } from "../stmt"
-import * as Stmts from "../stmts"
-import { Word } from "../word"
-import * as Exps from "../words"
-
-export function matchStmt(sexp: Sexp): Stmt {
-  return match<Stmt>(sexp, [
-    [
-      ["defcons", v("name"), v("inputArity"), v("outputArity")],
-      ({ name, inputArity, outputArity }) =>
-        new Stmts.Defcons(
-          matchSymbol(name),
-          matchNumber(inputArity),
-          matchNumber(outputArity),
-          sexp.span,
-        ),
-    ],
-    [
-      ["defelim", v("name"), v("inputArity"), v("outputArity")],
-      ({ name, inputArity, outputArity }) =>
-        new Stmts.Defelim(
-          matchSymbol(name),
-          matchNumber(inputArity),
-          matchNumber(outputArity),
-          sexp.span,
-        ),
-    ],
-    [
-      list(["defnet", v("name")], v("words")),
-      ({ name, input, output, words }) =>
-        new Stmts.Defnet(matchSymbol(name), matchExps(words), sexp.span),
-    ],
-    [
-      list(["defrule", [v("start"), v("end")]], v("words")),
-      ({ start, end, words }) =>
-        new Stmts.Defrule(
-          matchSymbol(start),
-          matchSymbol(end),
-          matchExps(words),
-          sexp.span,
-        ),
-    ],
-  ])
-}
-
-function matchExps(sexp: Sexp): Array<Word> {
-  return matchList(sexp, matchExp)
-}
-
-function matchExp(sexp: Sexp): Word {
-  return match<Word>(sexp, [
-    [
-      list(["let"], v("names")),
-      ({ names }) => new Exps.Let(matchList(names, matchSymbol), sexp.span),
-    ],
-    [v("name"), ({ name }) => new Exps.Call(matchSymbol(sexp), sexp.span)],
-  ])
-}
diff --git a/src/lang/syntax/matchers/index.ts b/src/lang/syntax/matchers/index.ts
new file mode 100644
index 00000000..55351fa3
--- /dev/null
+++ b/src/lang/syntax/matchers/index.ts
@@ -0,0 +1,3 @@
+export * from "./name_matcher"
+export * from "./stmt_matcher"
+export * from "./word_matcher"
diff --git a/src/lang/syntax/matchers/name_matcher.ts b/src/lang/syntax/matchers/name_matcher.ts
new file mode 100644
index 00000000..79175a76
--- /dev/null
+++ b/src/lang/syntax/matchers/name_matcher.ts
@@ -0,0 +1,10 @@
+import * as pt from "@cicada-lang/partech"
+
+export function variable_names_matcher(tree: pt.Tree): Array<string> {
+  return pt.matcher({
+    "variable_names:variable_names": ({ variable_names, last_name }) => [
+      ...pt.matchers.zero_or_more_matcher(variable_names).map(pt.str),
+      pt.str(last_name),
+    ],
+  })(tree)
+}
diff --git a/src/lang/syntax/matchers/stmt_matcher.ts b/src/lang/syntax/matchers/stmt_matcher.ts
new file mode 100644
index 00000000..c20dfd1e
--- /dev/null
+++ b/src/lang/syntax/matchers/stmt_matcher.ts
@@ -0,0 +1,39 @@
+import * as pt from "@cicada-lang/partech"
+import type { Stmt } from "../../stmt"
+import * as Stmts from "../../stmts"
+import * as matchers from "../matchers"
+
+export function stmt_matcher(tree: pt.Tree): Stmt {
+  return pt.matcher<Stmt>({
+    "stmt:defcons": ({ name, inputArity, outputArity }, { span }) =>
+      new Stmts.Defcons(
+        pt.str(name),
+        Number(pt.str(inputArity)),
+        Number(pt.str(outputArity)),
+        span,
+      ),
+    "stmt:defelim": ({ name, inputArity, outputArity }, { span }) =>
+      new Stmts.Defelim(
+        pt.str(name),
+        Number(pt.str(inputArity)),
+        Number(pt.str(outputArity)),
+        span,
+      ),
+    "stmt:defru": ({ start, end, words }, { span }) =>
+      new Stmts.Defrule(
+        pt.str(start),
+        pt.str(end),
+        matchers.words_matcher(words),
+        span,
+      ),
+    "stmt:defnet": ({ name, words }, { span }) =>
+      new Stmts.Defnet(pt.str(name), matchers.words_matcher(words), span),
+  })(tree)
+}
+
+export function stmts_matcher(tree: pt.Tree): Array<Stmt> {
+  return pt.matcher({
+    "stmts:stmts": ({ stmts }) =>
+      pt.matchers.zero_or_more_matcher(stmts).map(stmt_matcher),
+  })(tree)
+}
diff --git a/src/lang/syntax/matchers/word_matcher.ts b/src/lang/syntax/matchers/word_matcher.ts
new file mode 100644
index 00000000..b522ede9
--- /dev/null
+++ b/src/lang/syntax/matchers/word_matcher.ts
@@ -0,0 +1,17 @@
+import * as pt from "@cicada-lang/partech"
+import { Word } from "../../word"
+import * as Words from "../../words"
+
+export function word_matcher(tree: pt.Tree): Word {
+  return pt.matcher<Word>({
+    "word:call": ({ name }, { span }) => new Words.Call(pt.str(name), span),
+    "word:let": ({ name }, { span }) => new Words.Let([pt.str(name)], span),
+  })(tree)
+}
+
+export function words_matcher(tree: pt.Tree): Array<Word> {
+  return pt.matcher({
+    "words:words": ({ words }) =>
+      pt.matchers.zero_or_more_matcher(words).map(word_matcher),
+  })(tree)
+}