Validates that a value is not equal to a given reference value using an Eq comparator.

NotEqual enforces an inequality constraint of the form: "value must not equal X".

Equality is defined by an Eq instance, not by structural equality.

Options

• :value (required) The reference value to compare against.

• :eq (optional) An equality comparator. Defaults to Funx.Eq.Protocol.

• :message (optional) A custom error message callback (value -> String.t()) used to override the default error message on failure.

Semantics

• If the value does not equal the reference value under the given Eq, validation succeeds.
• If the value equals the reference value, validation fails.
• Nothing values are preserved and treated as not applicable.
• Just values are unwrapped before comparison.