diff --git a/Readme.md b/Readme.md
index e649e8f..1a24d75 100755
--- a/Readme.md
+++ b/Readme.md
@@ -1,6 +1,8 @@
 # Meow lang
 
-Meow lang is a programming language that compiles to *cat*, another language that is hard to read but easy to execute. Meow's syntax is easier to read than cat, but meow and cat are equivalent.
+Meow lang is a programming language that compiles to *catlet*, another language that is hard to read but easy to execute. Meow's syntax is easier to read than catlet, but meow and catlet are equivalent.
+
+(It's called *catlet* because the only available two keywords are `cat` and `let`)
 
 Its main design purpose is to do experiments with "string substitution".
 
@@ -21,7 +23,7 @@ The only available data type is **String**. (However, you can encode other data
 
 cargo run repl
 
-# Now you can use the REPL to evaluate (cat) expressions
+# Now you can use the REPL to evaluate (catlet) expressions
 ```
 
 Example:
@@ -40,7 +42,8 @@ hello world
 - [Syntax](./docs/Syntax.md)
 - [Encoding](./docs/Encoding.md)
 - [Double Substitution Lemma](./docs/DSL.md)
+- [i Expressions](./docs/i-expr.md)
 
 ## Examples
 
-See [syn.meow](./examples/syn.meow), which has compiling result [syn.cat](./examples/syn.cat).
+See [syn.meow](./examples/syn.meow), which has compiled result [syn.cat](./examples/syn.cat).
diff --git a/examples/syn.meow b/examples/syn.meow
index 8dd2b44..341aab2 100644
--- a/examples/syn.meow
+++ b/examples/syn.meow
@@ -133,15 +133,15 @@ ten() {
 }
 
 revdigit(x) {
-    "S0"="1";
-    "SS0"="2";
-    "SSS0"="3";
-    "SSSS0"="4";
-    "SSSSS0"="5";
-    "SSSSSS0"="6";
-    "SSSSSSS0"="7";
-    "SSSSSSSS0"="8";
-    "SSSSSSSSS0"="9";
+    "S0" = "1";
+    "SS0" = "2";
+    "SSS0" = "3";
+    "SSSS0" = "4";
+    "SSSSS0" = "5";
+    "SSSSSS0" = "6";
+    "SSSSSSS0" = "7";
+    "SSSSSSSS0" = "8";
+    "SSSSSSSSS0" = "9";
     x
 }
 
@@ -168,14 +168,18 @@ num(x) {
     var hd = head(x);
     var hdnum = revdigit(hd);
     var remain = {
-        "$"+ hdnum = "";
-        "$"+x
+        "$" + hdnum = "";
+        "$" + x
     };
-    !(if(eq(len(x), "S0"), spack(digit(x)), `add mul "`+ hd + `" exp ten "`+nl+`" `+`num "` + remain + `"`))
+    !(if(
+        eq(len(x), "S0"),
+        spack(digit(x)),
+        `add mul "` + hd + `" exp ten "` + nl + `" ` + `num "` + remain + `"`
+    ))
 }
 
 spack(x) {
-    `"`+x+`"`
+    `"` + x + `"`
 }
 
 leq(x,y) {
@@ -191,7 +195,11 @@ show(x) {
         "SSSSSSSSSS" = "S";
         sub(x,la)
     };
-    !(if(leq(len(x), digit("9")), spack(revdigit(x)) , `cat show "` + rem + `" revdigit "` + la + `"`))
+    !(if(
+        leq(len(x), digit("9")),
+        spack(revdigit(x)),
+        `cat show "` + rem + `" revdigit "` + la + `"`
+    ))
 }
 
 fib(x) {