diff --git a/docs/syntax.md b/docs/syntax.md
index e1bf878..bd958df 100644
--- a/docs/syntax.md
+++ b/docs/syntax.md
@@ -8,6 +8,23 @@ Substitute the output of a module into another module's arguments by enclosing t
 
 Access a variable by prefixing it's name with a `$` dollar sign.
 
+## Data Types
+
+Kyn supports several data types: strings, integers, doubles (floating-point numbers), and lists.
+
+### Strings
+Strings are enclosed in double quotes.
+`let myString = "Hello, World!"`
+
+### Numbers
+Numbers can be integers or doubles.
+`let myInt = 42`
+`let myDouble = 3.14`
+
+### Lists
+Lists are ordered collections of values, enclosed in square brackets.
+`let myList = [1, "two", 3.0, ["nested", "list"]]`
+
 ## Input/Output
 
 ### print
@@ -18,7 +35,7 @@ Example: `print "Hello!"`
 
 ### println
 
-Prints all the arguments provided to the console, appending a newline after.
+Prints all the arguments provided to theconsole, appending a newline after.
 
 Example: `println "Hello!"`
 
@@ -30,25 +47,76 @@ Example: `input` (this does nothing but prompt the user)
 
 Another example: `let userInput = (input)`
 
-## Data
+## Variables and Data
 
 ### let
 
-Defines a variable to the value provided.
+Defines a variable to the value provided. If no value is provided, it defaults to an empty string.
 
 Example: `let myVar = "Hello!"`
+Example: `let anotherVar`
+
+### concat
+
+Concatenates multiple strings or numbers together.
+
+Example: `println (concat "There are " 3 " apples.")` // Prints "There are 3 apples."
+
+## Indexed Operations
+
+You can access elements of lists and characters of strings by their index (starting from 0).
+
+### Get element
+
+Syntax: `(variable index)`
+
+```kyn
+let myList = ["a", "b", "c"]
+println (myList 1) // Prints "b"
+
+let myString = "hello"
+println (myString 2) // Prints "l"
+```
+
+### Set element
+
+Syntax: `variable index = newValue`
+
+```kyn
+let myList = ["a", "b", "c"]
+myList 1 = "z"
+println $myList // Prints ["a", "z", "c"]
+
+let myString = "hello"
+myString 0 = "j"
+println $myString // Prints "jello"
+```
+
+### size
+
+You can get the number of elements in a list or characters in a string using `size`.
+
+Syntax: `(variable size)`
+
+```kyn
+let myList = [1, 2, 3, 4]
+println (myList size) // Prints 4
+
+let myString = "hello"
+println (myString size) // Prints 5
+```
 
 ## Computations
 
 ### math
 
-Computes a mathematical expression. Supports addition (+), subtraction (-), multiplication (*), division (/), power to (^) and mod (%).
+Computes a mathematical expression. Supports addition (+), subtraction (-), multiplication (*), division (/), power to (^) and mod (%). Follows order of operations.
 
 Example: `math 4 * 3 + 12 / 4 - 5 ^ 3`
 
 ### compare
 
-Compares two values. Supports equal (==) and inequal (!=) on all values. Supports greater than (>), greater than or equal to (>=), lesser than (<), and lesser than or equal to (<=) for numbers.
+Compares two values. Supports equal (==) and inequal (!=) on all values. Supports greater than (>), greater than or equal to (>=), lesser than (<), and lesser than or equal to (<=) for numbers. Returns "1" for true and "0" for false.
 
 ## Control Flow
 
@@ -58,11 +126,11 @@ Exits the program with a return code. If no return code or an invalid return cod
 
 ### if
 
-Runs a module. If the output of that module is 0 or "false", skips the code in that block. If an `else` block is provided after, that is running instead. Otherwise, the code inside the `if` block is ran.
+Runs a block of code if a condition is true. An optional `else` block can be provided. The condition is considered true if it's not 0, "false", or an empty string/list.
 
 Example:
 
-```
+```kyn
 if compare 1 == 1 {
     println "1 is the same as 1"
 } else {
@@ -72,15 +140,43 @@ if compare 1 == 1 {
 
 ### while
 
-Runs a module. If the output of that module is 0 or "false", skips the code in that block. Otherwise, loops the block until the module ran is 0 or "false".
+Runs a block of code repeatedly as long as a condition is true.
 
 Example:
 
-```
+```kyn
 let number = 0
 
-while compare $number <= 10 {
-    number = ($number + 1)
+while compare $number < 10 {
+    number = (math $number + 1)
     println $number
 }
 ```
+
+### fun
+
+Defines a function with a name, a list of arguments, and a body.
+
+```kyn
+fun multiply a b {
+    return (math $a * $b)
+}
+
+let product = (multiply 7 6)
+println $product # Prints 42
+```
+
+### return
+
+Exits a function, optionally returning a value.
+
+```kyn
+fun myFunc {
+    println "doing stuff..."
+    return "done"
+    println "this will not print"
+}
+
+let result = (myFunc)
+println $result # Prints "doing stuff..." and then "done"
+```
\ No newline at end of file
diff --git a/src/datatypes/lists/lists.cpp b/src/datatypes/lists/lists.cpp
index 1a1fde3..8030ed5 100644
--- a/src/datatypes/lists/lists.cpp
+++ b/src/datatypes/lists/lists.cpp
@@ -1,6 +1,5 @@
 #include "lists.h"
 #include "../../error/error.h"
-#include "../../modules/math/math.h"
 #include "../../data/data.h"
 #include "../../utils/trim/trim.h"
 #include "../../utils/evaluate/evaluate.h"
@@ -47,7 +46,7 @@ Value handleListGet(const Value& subject, const std::vector<Value>& args) {
         error("List accessor must be an integer or \"size\"");
         return Value();
     }
-    
+
     int index = accessor.int_val;
     if (index < 0 || (size_t)index >= subject.list.size()) {
         error("List index out of bounds");
diff --git a/src/defs/defs.cpp b/src/defs/defs.cpp
index 88f58f6..186dce7 100644
--- a/src/defs/defs.cpp
+++ b/src/defs/defs.cpp
@@ -232,7 +232,9 @@ std::vector<Value> split(std::string line) {
     char bracket_type = 0;
 
     for (char chr : line) {
-        if (chr == ' ' && !instring && brackets == 0 && !buf.empty()) {
+        if (chr == '#' && !instring) {
+            break;
+        } else if (chr == ' ' && !instring && brackets == 0 && !buf.empty()) {
             if (buf[0] == '$') {
                 splitvals.push_back(Value(Varname(buf)));
             } else {
diff --git a/src/modules/compare/compare.cpp b/src/modules/compare/compare.cpp
index 105ad54..cf9a539 100644
--- a/src/modules/compare/compare.cpp
+++ b/src/modules/compare/compare.cpp
@@ -1,6 +1,5 @@
 #include "compare.h"
 #include "../../error/error.h"
-#include "../math/math.h"
 
 Value modules::compare(std::vector<Value> values) {
     if (values.size() != 3) {
diff --git a/src/parser/parser.cpp b/src/parser/parser.cpp
index 0bf3f17..6f03a1c 100644
--- a/src/parser/parser.cpp
+++ b/src/parser/parser.cpp
@@ -44,6 +44,11 @@ std::vector<Instruction> parse(std::string program) {
             continue;
         }
 
+        // Ignore commented lines
+        if (line[0] == '#') {
+            continue;
+        }
+
         if (line.rfind("if", 0) == 0) {
             Instruction if_inst;
             if_inst.instruction = InstructionType::If;
diff --git a/tests/let.kyn b/tests/let.kyn
new file mode 100644
index 0000000..9384694
--- /dev/null
+++ b/tests/let.kyn
@@ -0,0 +1,3 @@
+let myVar = "hello there!"
+
+println $myVar