Enum DerivationSignatureProblem 

pub enum DerivationSignatureProblem {
    NoClassValue,
    ResultMentionsClassVariable,
    Shape,
}

What is wrong with the signature of a member a derivation was written for — see Error::DerivationSignature.

Variants

NoClassValue

No parameter of the member holds the class variable: bottom : a and allValues : List a. A derivation walks values of the type, and there is none to walk, so it would have to build one from a description of the type’s constructors.

ResultMentionsClassVariable

The class variable is in the answer: add : a -> a -> a. The walk would be asked for another value of the type it is walking.

Shape

Some other shape: a derivation is for a -> a -> R and a -> R.

Trait Implementations

impl Clone for DerivationSignatureProblem

fn clone(&self) -> DerivationSignatureProblem

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for DerivationSignatureProblem

impl Debug for DerivationSignatureProblem

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for DerivationSignatureProblem

impl PartialEq for DerivationSignatureProblem

fn eq(&self, other: &DerivationSignatureProblem) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for DerivationSignatureProblem