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|
use crate::ast::*;
use crate::checker_state::*;
use std::iter::zip;
use tracing::instrument;
impl CheckerState {
#[instrument(skip(self), level = "debug", fields(%signature))]
pub fn check_signature(&self, signature: &Signature) -> Result<Signature, CheckerError> {
match signature {
Signature::Set => Ok(Signature::Set),
Signature::Var(v) => {
let deref = self.lookup_signature(&v)?;
Ok(deref.clone())
}
Signature::Ext { params, codomain } => {
let mut ctx = self.clone();
let params = params
.iter()
.map(|p| {
let set = ctx.check_set(&p.set)?;
let canon = ctx.make_element_binding(p.name.clone(), set.clone())?;
Ok(Param { set, name: canon })
})
.collect::<Result<Vec<_>, _>>()?;
let codomain = Box::new(ctx.check_signature(codomain)?);
Ok(Signature::Ext { params, codomain })
}
Signature::Theory(fields) => {
let mut ctx = self.clone();
let temp_name = ctx.make_unique_name();
let mut new_fields = Vec::new();
for SigField { signature, name } in fields {
let signature = ctx.check_signature(signature)?;
ctx.add_instance(name.clone(), InstanceValue::Hypothetical, signature.clone())?;
// And lo, the special case, our chosen canonical form
if signature == Signature::Set {
ctx.add_set(
name.clone(),
Set::ClaimedSet(Instance::Var(name.clone())).into(),
)?;
}
new_fields.push(SigField {
name: name.clone(),
signature,
});
// We must iteratively add the entire signature so that
// field lookup does something, as we rely on that for type
// checking. We could hack together a signature i suppose,
// but the cleanest thing is to add the truncations of this
// signature. In any event the context is discarded
// afterward.
ctx.add_signature(&temp_name, Signature::Theory(new_fields.clone()), true)?;
}
Ok(Signature::Theory(new_fields))
}
}
}
#[instrument(skip(self), level = "debug", fields(%instance, ?signature))]
pub fn check_instance(
&self,
instance: &Instance,
signature: Option<&Signature>,
) -> Result<Instance, CheckerError> {
match instance {
Instance::SetCoerce(set) => {
if let Some(signature) = signature
&& *signature != Signature::Set
{
return Err(CheckerError::WrongSignatureForInstance {
value: instance.clone().into(),
real: Signature::Set,
claimed: signature.clone(),
});
};
let set = Box::new(self.check_set(set)?);
if let Set::ClaimedSet(inner) = *set {
Ok(inner)
} else {
Ok(Instance::SetCoerce(set))
}
}
Instance::Var(v) => {
// Exactly the same discipline as for Element::Var, see there
// for some sparse comments
let lookup = self.lookup_instance(&v)?;
if let Some(signature) = signature
&& !self.equal(signature, &lookup.container)
{
return Err(CheckerError::WrongSignatureForInstance {
value: instance.clone().into(),
claimed: signature.clone(),
real: lookup.container.clone(),
});
}
if let InstanceValue::Concrete(ref deref) = lookup.value {
Ok(deref.clone())
} else {
Ok(Instance::Var(v.clone()))
}
}
Instance::Record(assignations) => {
// once again, mutatis mutandis from elements
let (instance_fnames, instance_finstances): (Vec<String>, Vec<&Instance>) =
assignations
.iter()
.map(|InstAssign { name, instance }| (name.clone(), instance))
.unzip();
let mut instance_fnames_sorted = instance_fnames.clone();
instance_fnames_sorted.sort();
let signature_fsigs: Vec<Option<Signature>>;
if let Some(signature) = signature {
let rej = |reason| CheckerError::InstanceDoesNotBelong {
instance: instance.clone(),
claimed: signature.clone(),
reason: reason,
};
let fields = if let Signature::Theory(fields) = signature {
Ok(fields)
} else {
Err(rej("signature has no fields".to_string()))
}?;
let signature_fnames: Vec<String>;
(signature_fnames, signature_fsigs) = fields
.iter()
.map(|SigField { name, signature }| {
(name.clone(), signature.clone().into())
})
.unzip();
let mut signature_fnames_sorted = signature_fnames.clone();
signature_fnames_sorted.sort();
if signature_fnames_sorted != instance_fnames_sorted {
return Err(rej(format!(
"expected [{}] but found [{}]",
signature_fnames.join(", "),
instance_fnames.join(", "),
)));
}
} else {
signature_fsigs = std::iter::repeat(None)
.take(instance_finstances.len())
.collect();
}
let sub_els = zip(instance_finstances, signature_fsigs)
.map(|(e_f, e_s)| self.check_instance(e_f, (&e_s).into()))
.collect::<Result<Vec<_>, _>>()?;
let assignations = zip(instance_fnames, sub_els)
.map(|(name, instance)| InstAssign { name, instance })
.collect();
Ok(Instance::Record(assignations))
}
Instance::Project { instance, field } => {
let Field {
field: field_signature,
owner: owner_signature,
} = self.lookup_signature_field(&field)?;
if let Some(signature) = signature
&& !self.equal(signature, field_signature)
{
return Err(CheckerError::WrongSignatureForInstance {
value: (*instance.clone()).into(),
claimed: signature.clone(),
real: field_signature.clone(),
});
}
let inner = self.check_instance(instance, owner_signature.into())?;
match inner {
Instance::Var(_) | Instance::Project { .. } => Ok(Instance::Project {
instance: Box::new(inner),
field: field.clone(),
}),
Instance::Record(assignations) => {
let sub_element = assignations
.into_iter()
.find(|a| a.name == *field)
.expect(
"invariant violation: record missing field that was type-checked",
)
.instance;
Ok(sub_element)
}
_ => panic!(
"invariant violation: check_instance returned neither a record or stuck computation for record set"
),
}
}
Instance::For { .. } => {
todo!("instance for")
}
Instance::App(inner, element) => {
let inner = self.check_instance(inner, None)?;
match &inner {
Instance::Var(v) => {
let field = self.lookup_signature_field(&v)?;
let Signature::Ext {
ref params,
ref codomain,
} = field.field
else {
return Err(CheckerError::WrongSignatureForInstance {
value: inner.clone().into(),
claimed: Signature::Ext {
params: vec![Param {
name: "...".to_string(),
set: Set::Var("...".to_string()),
}],
codomain: Box::new(Signature::Var("...".to_string())),
},
real: field.owner.clone(),
});
};
if params.is_empty() {
panic!(
"It should have been impossible to construct an Ext with no params, but here we are"
);
}
if params.len() == 1
&& let Some(signature) = signature
{
if !self.equal(&**codomain, signature) {
return Err(CheckerError::WrongSignatureForInstance {
value: instance.clone().into(),
claimed: signature.clone(),
real: *codomain.clone(),
});
}
}
let element = self.check_element(element, ¶ms[0].set)?;
Ok(Instance::App(
Box::new(Instance::Var(v.clone())),
Box::new(element),
))
}
Instance::For { params, body } => {
if params.is_empty() {
panic!(
"It should have been impossible to construct a For with no params, but here we are"
);
}
let mut ctx = self.clone();
for (idx, param) in params.iter().enumerate() {
let Param {
name: param_name,
set: param_set,
} = param.clone();
if idx == 0 {
let element = self.check_element(&*element, ¶m_set)?;
ctx.make_element_definition(param_name, element, param_set)?;
} else {
ctx.make_element_binding(param_name, param_set)?;
}
}
let instance = ctx.check_instance(body, signature)?;
if params.len() == 1 {
Ok(instance)
} else {
Ok(Instance::For {
params: params[1..].iter().map(|p| p.clone()).collect(),
body: Box::new(instance),
})
}
}
Instance::Record(_) | Instance::SetCoerce(_) => {
Err(CheckerError::NonFunctionalInstance {
instance: inner,
element: *element.clone(),
})
}
Instance::Project { .. } | Instance::App(_, _) => panic!(
"invariant violation: we did not completely expand the inner instance in our app"
),
}
}
}
}
}
|
