> For the complete documentation index, see [llms.txt](https://docs.uniot.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.uniot.io/platform/sandbox/visual-editor/logic.md).
# Logic
Logic blocks enable decision-making in your scripts. Use these blocks to compare values, create conditional behaviors, combine multiple conditions, and control program flow based on device states.
## value
A boolean constant that represents true or false. Use this block to provide boolean values to conditions, comparisons, or variables.
**Parameters:**
* **Value** (Boolean): Select `true` or `false`
**Returns:**
* **Boolean**: `#t` for true, `()` for false (Lisp values)
**Example:**
Set initial values
## if
Executes code conditionally based on whether a condition is true. This is the fundamental building block for creating decision-based behavior in your scripts.
**Parameters:**
* **Condition** (Boolean): The condition to evaluate
**Example:**
Send event if button was clicked
### Adding else if and else Clauses
The basic `if` block can be extended with additional conditions and fallback logic. Click the gear icon to open the configuration panel:
Drag `else if` and `else` blocks from the left panel to build your conditional logic. You can add multiple `else if` clauses but only one `else` clause. Reorder or remove clauses as needed, then click the gear icon to close:
## comparison
Compares two values using mathematical or equality operators. Use this to check sensor thresholds, compare states, or validate ranges.
**Parameters:**
* **Left Value** (Number): The first value to compare
* **Operator**: Choose from `=` (equal), `≠` (not equal), `<` (less than), `>` (greater than), `≤` (less or equal), `≥` (greater or equal)
* **Right Value** (Number): The second value to compare
**Returns:**
* **Boolean**: `#t` (true) if the comparison is satisfied, `()` (false) otherwise
**Example:**
Check humidity and send event when it is too high
## and
Returns true only if both conditions are true. Use this to combine multiple requirements that must all be satisfied.
**Parameters:**
* **Input A** (Boolean): The first condition
* **Input B** (Boolean): The second condition
**Returns:**
* **Boolean**: `#t` (true) if both inputs are true, `()` (false) otherwise
**Example:**
Multiple condition check
## or
Returns true if at least one condition is true. Use this when any of several conditions should trigger an action.
**Parameters:**
* **Input A** (Boolean): The first condition
* **Input B** (Boolean): The second condition
**Returns:**
* **Boolean**: `#t` (true) if at least one input is true, `()` (false) otherwise
**Example:**
Humidity alert
## not
Inverts a boolean value, turning true into false and false into true. Use this to reverse conditions or check for the opposite of a state.
**Parameters:**
* **Input** (Boolean): The boolean value to invert
**Returns:**
* **Boolean**: `#t` (true) becomes `()` (false), and vice versa
**Example:**
Toggle state by button click
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