diff --git a/TODO.md b/TODO.md
index 4fa99ed5..996b8dc0 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,3 @@
-use unicode for subscript number
-
 `connect` v.s. `reconnect`
 
 - `reconnect` is used in `PortReconnect`
diff --git a/docs/tests/DiffList.inet.one_two_soles.finial.txt b/docs/tests/DiffList.inet.one_two_soles.finial.txt
index 9d994dc2..5536acfd 100644
--- a/docs/tests/DiffList.inet.one_two_soles.finial.txt
+++ b/docs/tests/DiffList.inet.one_two_soles.finial.txt
@@ -1,8 +1,8 @@
-(sole#1)-return head-(cons#2)
-(sole#5)-return head-(cons#6)
-(sole#7)-return head-(cons#8)
-(cons#6)-return tail-(cons#8)
-(cons#6)-tail left-(diff#13)
-(cons#2)-return return-(cons#8)
-(cons#2)-tail right-(diff#13)
-(diff#13)-return
\ No newline at end of file
+(sole₁)-return head-(cons₂)
+(sole₅)-return head-(cons₆)
+(sole₇)-return head-(cons₈)
+(cons₆)-return tail-(cons₈)
+(cons₆)-tail left-(diff₁₃)
+(cons₂)-return return-(cons₈)
+(cons₂)-tail right-(diff₁₃)
+(diff₁₃)-return
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.one_two_soles.initial.txt b/docs/tests/DiffList.inet.one_two_soles.initial.txt
index 4a5b5651..0ce30ed1 100644
--- a/docs/tests/DiffList.inet.one_two_soles.initial.txt
+++ b/docs/tests/DiffList.inet.one_two_soles.initial.txt
@@ -1,11 +1,11 @@
-(diff#9)-return!left-(diff_append#10)
-(sole#1)-return head-(cons#2)
-(cons#2)-return left-(diff#3)
-(sole#5)-return head-(cons#6)
-(sole#7)-return head-(cons#8)
-(cons#6)-return tail-(cons#8)
-(cons#8)-return left-(diff#9)
-(diff#3)-return right-(diff_append#10)
-(diff#3)-right tail-(cons#2)
-(diff#9)-right tail-(cons#6)
-(diff_append#10)-return
\ No newline at end of file
+(diff₉)-return!left-(diff_append₁₀)
+(sole₁)-return head-(cons₂)
+(cons₂)-return left-(diff₃)
+(sole₅)-return head-(cons₆)
+(sole₇)-return head-(cons₈)
+(cons₆)-return tail-(cons₈)
+(cons₈)-return left-(diff₉)
+(diff₃)-return right-(diff_append₁₀)
+(diff₃)-right tail-(cons₂)
+(diff₉)-right tail-(cons₆)
+(diff_append₁₀)-return
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.two_two_soles.finial.txt b/docs/tests/DiffList.inet.two_two_soles.finial.txt
index 3a79ab2e..a2325cb4 100644
--- a/docs/tests/DiffList.inet.two_two_soles.finial.txt
+++ b/docs/tests/DiffList.inet.two_two_soles.finial.txt
@@ -1,10 +1,10 @@
-(sole#15)-return head-(cons#16)
-(sole#17)-return head-(cons#18)
-(cons#16)-return tail-(cons#18)
-(sole#21)-return head-(cons#22)
-(sole#23)-return head-(cons#24)
-(cons#22)-return tail-(cons#24)
-(cons#22)-tail left-(diff#29)
-(cons#18)-return return-(cons#24)
-(cons#16)-tail right-(diff#29)
-(diff#29)-return
\ No newline at end of file
+(sole₁₅)-return head-(cons₁₆)
+(sole₁₇)-return head-(cons₁₈)
+(cons₁₆)-return tail-(cons₁₈)
+(sole₂₁)-return head-(cons₂₂)
+(sole₂₃)-return head-(cons₂₄)
+(cons₂₂)-return tail-(cons₂₄)
+(cons₂₂)-tail left-(diff₂₉)
+(cons₁₈)-return return-(cons₂₄)
+(cons₁₆)-tail right-(diff₂₉)
+(diff₂₉)-return
\ No newline at end of file
diff --git a/docs/tests/DiffList.inet.two_two_soles.initial.txt b/docs/tests/DiffList.inet.two_two_soles.initial.txt
index 1580ac31..02e15d96 100644
--- a/docs/tests/DiffList.inet.two_two_soles.initial.txt
+++ b/docs/tests/DiffList.inet.two_two_soles.initial.txt
@@ -1,13 +1,13 @@
-(diff#25)-return!left-(diff_append#26)
-(sole#15)-return head-(cons#16)
-(sole#17)-return head-(cons#18)
-(cons#16)-return tail-(cons#18)
-(cons#18)-return left-(diff#19)
-(sole#21)-return head-(cons#22)
-(sole#23)-return head-(cons#24)
-(cons#22)-return tail-(cons#24)
-(cons#24)-return left-(diff#25)
-(diff#19)-return right-(diff_append#26)
-(diff#19)-right tail-(cons#16)
-(diff#25)-right tail-(cons#22)
-(diff_append#26)-return
\ No newline at end of file
+(diff₂₅)-return!left-(diff_append₂₆)
+(sole₁₅)-return head-(cons₁₆)
+(sole₁₇)-return head-(cons₁₈)
+(cons₁₆)-return tail-(cons₁₈)
+(cons₁₈)-return left-(diff₁₉)
+(sole₂₁)-return head-(cons₂₂)
+(sole₂₃)-return head-(cons₂₄)
+(cons₂₂)-return tail-(cons₂₄)
+(cons₂₄)-return left-(diff₂₅)
+(diff₁₉)-return right-(diff_append₂₆)
+(diff₁₉)-right tail-(cons₁₆)
+(diff₂₅)-right tail-(cons₂₂)
+(diff_append₂₆)-return
\ 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
index f5e31c39..094d3842 100644
--- a/docs/tests/List.inet.six_soles.finial.txt
+++ b/docs/tests/List.inet.six_soles.finial.txt
@@ -1,13 +1,13 @@
-(sole#12)-return head-(cons#17)
-(sole#5)-return head-(cons#19)
-(cons#19)-return tail-(cons#17)
-(sole#10)-return head-(cons#21)
-(cons#21)-return tail-(cons#19)
-(sole#3)-return head-(cons#23)
-(cons#23)-return tail-(cons#21)
-(sole#8)-return head-(cons#25)
-(cons#25)-return tail-(cons#23)
-(sole#1)-return head-(cons#27)
-(cons#27)-return tail-(cons#25)
-(null#0)-return tail-(cons#27)
-(cons#17)-return
\ No newline at end of file
+(sole₁₂)-return head-(cons₁₇)
+(sole₅)-return head-(cons₁₉)
+(cons₁₉)-return tail-(cons₁₇)
+(sole₁₀)-return head-(cons₂₁)
+(cons₂₁)-return tail-(cons₁₉)
+(sole₃)-return head-(cons₂₃)
+(cons₂₃)-return tail-(cons₂₁)
+(sole₈)-return head-(cons₂₅)
+(cons₂₅)-return tail-(cons₂₃)
+(sole₁)-return head-(cons₂₇)
+(cons₂₇)-return tail-(cons₂₅)
+(null₀)-return tail-(cons₂₇)
+(cons₁₇)-return
\ No newline at end of file
diff --git a/docs/tests/List.inet.six_soles.initial.txt b/docs/tests/List.inet.six_soles.initial.txt
index 61e97d99..9ecee03c 100644
--- a/docs/tests/List.inet.six_soles.initial.txt
+++ b/docs/tests/List.inet.six_soles.initial.txt
@@ -1,15 +1,15 @@
-(cons#13)-return!left-(append#14)
-(sole#1)-return head-(cons#2)
-(null#0)-return tail-(cons#2)
-(sole#3)-return head-(cons#4)
-(cons#2)-return tail-(cons#4)
-(sole#5)-return head-(cons#6)
-(cons#4)-return tail-(cons#6)
-(sole#8)-return head-(cons#9)
-(null#7)-return tail-(cons#9)
-(sole#10)-return head-(cons#11)
-(cons#9)-return tail-(cons#11)
-(sole#12)-return head-(cons#13)
-(cons#11)-return tail-(cons#13)
-(cons#6)-return right-(append#14)
-(append#14)-return
\ No newline at end of file
+(cons₁₃)-return!left-(append₁₄)
+(sole₁)-return head-(cons₂)
+(null₀)-return tail-(cons₂)
+(sole₃)-return head-(cons₄)
+(cons₂)-return tail-(cons₄)
+(sole₅)-return head-(cons₆)
+(cons₄)-return tail-(cons₆)
+(sole₈)-return head-(cons₉)
+(null₇)-return tail-(cons₉)
+(sole₁₀)-return head-(cons₁₁)
+(cons₉)-return tail-(cons₁₁)
+(sole₁₂)-return head-(cons₁₃)
+(cons₁₁)-return tail-(cons₁₃)
+(cons₆)-return right-(append₁₄)
+(append₁₄)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.four.finial.txt b/docs/tests/Nat.inet.four.finial.txt
index b8ee8c55..2a3b0902 100644
--- a/docs/tests/Nat.inet.four.finial.txt
+++ b/docs/tests/Nat.inet.four.finial.txt
@@ -1,5 +1,5 @@
-(add1#35)-return prev-(add1#29)
-(add1#37)-return prev-(add1#35)
-(add1#41)-return prev-(add1#37)
-(zero#14)-return prev-(add1#41)
-(add1#29)-return
\ No newline at end of file
+(add1₃₅)-return prev-(add1₂₉)
+(add1₃₇)-return prev-(add1₃₅)
+(add1₄₁)-return prev-(add1₃₇)
+(zero₁₄)-return prev-(add1₄₁)
+(add1₂₉)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.four.initial.txt b/docs/tests/Nat.inet.four.initial.txt
index 20add477..86f0d4ef 100644
--- a/docs/tests/Nat.inet.four.initial.txt
+++ b/docs/tests/Nat.inet.four.initial.txt
@@ -1,11 +1,11 @@
-(add1#17)-return!x-(add#18)
-(add1#22)-return!x-(add#23)
-(zero#14)-return prev-(add1#15)
-(zero#16)-return prev-(add1#17)
-(add1#15)-return y-(add#18)
-(zero#19)-return prev-(add1#20)
-(zero#21)-return prev-(add1#22)
-(add1#20)-return y-(add#23)
-(add#23)-return x-(add#24)
-(add#18)-return y-(add#24)
-(add#24)-return
\ No newline at end of file
+(add1₁₇)-return!x-(add₁₈)
+(add1₂₂)-return!x-(add₂₃)
+(zero₁₄)-return prev-(add1₁₅)
+(zero₁₆)-return prev-(add1₁₇)
+(add1₁₅)-return y-(add₁₈)
+(zero₁₉)-return prev-(add1₂₀)
+(zero₂₁)-return prev-(add1₂₂)
+(add1₂₀)-return y-(add₂₃)
+(add₂₃)-return x-(add₂₄)
+(add₁₈)-return y-(add₂₄)
+(add₂₄)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.two.finial.txt b/docs/tests/Nat.inet.two.finial.txt
index e8eab9f5..fdea242d 100644
--- a/docs/tests/Nat.inet.two.finial.txt
+++ b/docs/tests/Nat.inet.two.finial.txt
@@ -1,3 +1,3 @@
-(add1#13)-return prev-(add1#11)
-(zero#4)-return prev-(add1#13)
-(add1#11)-return
\ No newline at end of file
+(add1₁₃)-return prev-(add1₁₁)
+(zero₄)-return prev-(add1₁₃)
+(add1₁₁)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.two.initial.txt b/docs/tests/Nat.inet.two.initial.txt
index 09a9a9c8..a4afe7e1 100644
--- a/docs/tests/Nat.inet.two.initial.txt
+++ b/docs/tests/Nat.inet.two.initial.txt
@@ -1,5 +1,5 @@
-(add1#7)-return!x-(add#8)
-(zero#4)-return prev-(add1#5)
-(zero#6)-return prev-(add1#7)
-(add1#5)-return y-(add#8)
-(add#8)-return
\ No newline at end of file
+(add1₇)-return!x-(add₈)
+(zero₄)-return prev-(add1₅)
+(zero₆)-return prev-(add1₇)
+(add1₅)-return y-(add₈)
+(add₈)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.zero_zero_add.finial.txt b/docs/tests/Nat.inet.zero_zero_add.finial.txt
index 0ea06bae..fb8d110a 100644
--- a/docs/tests/Nat.inet.zero_zero_add.finial.txt
+++ b/docs/tests/Nat.inet.zero_zero_add.finial.txt
@@ -1 +1 @@
-(zero#0)-return
\ No newline at end of file
+(zero₀)-return
\ No newline at end of file
diff --git a/docs/tests/Nat.inet.zero_zero_add.initial.txt b/docs/tests/Nat.inet.zero_zero_add.initial.txt
index fadd96fa..de846e2d 100644
--- a/docs/tests/Nat.inet.zero_zero_add.initial.txt
+++ b/docs/tests/Nat.inet.zero_zero_add.initial.txt
@@ -1,3 +1,3 @@
-(zero#1)-return!x-(add#2)
-(zero#0)-return y-(add#2)
-(add#2)-return
\ No newline at end of file
+(zero₁)-return!x-(add₂)
+(zero₀)-return y-(add₂)
+(add₂)-return
\ No newline at end of file
diff --git a/src/renderers/formatNode.ts b/src/renderers/formatNode.ts
index 6f3bd3c9..5d361725 100644
--- a/src/renderers/formatNode.ts
+++ b/src/renderers/formatNode.ts
@@ -1,5 +1,22 @@
 import { Node } from "../lang/graph"
 
 export function formatNode(node: Node): string {
-  return `${node.name}#${node.id}`
+  const subscript = [...node.id.toString()]
+    .map((c) => numberSubscripts[c] || c)
+    .join("")
+
+  return `${node.name}${subscript}`
+}
+
+const numberSubscripts: Record<string, string> = {
+  "0": "₀",
+  "1": "₁",
+  "2": "₂",
+  "3": "₃",
+  "4": "₄",
+  "5": "₅",
+  "6": "₆",
+  "7": "₇",
+  "8": "₈",
+  "9": "₉",
 }