not?
Use not? to apply a logical NOT operation to the results of applying a specified value to an application function.
You can use any data type for the value argument as long as the app function takes that same data type and returns the resulting boolean value for the logical NOT operation performed by the not? function.
By convention, the data type <a> is used if an argument represents a type-bound parameter like the value argument in this function:
Basic syntax
To apply a logical NOT operation to the results of applying a specified value to an application function app, use the following syntax:
(not? app value)
Arguments
Use the following arguments to specify the application function and the value to be applied using the not? Pact function.
| Argument | Type | Description |
|---|---|---|
app | function x: <a> -> bool | Specifies the application function to apply the specified value to. The result of applying the specified value returns a boolean value. |
value | <a> | Specifies the value to be applied to the application function. |
Return value
The not? function returns a boolean value representing the logical negation of the result of applying the value to the application function.
Examples
The following example demonstrates how to use the not? function in the Pact REPL:
pact> (not? (> 20) 15)
false
In this example, the application function is (> 20) and the value is 15. Because the expression 20 > 15 evaluates to true, and not? negates this value, the not? function returns false.