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3 changed files with 206 additions and 1 deletions

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@ -2,7 +2,7 @@ use crate::bimap::Bimap;
//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\
#[derive(Eq, PartialEq, Hash, Clone, Debug)]
#[derive(Eq, PartialEq, Hash, Clone, Copy, Debug)]
pub enum TypeID {
Fun(u64),
Var(u64)

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@ -10,6 +10,7 @@ pub mod lnf;
pub mod pnf;
pub mod subtype;
pub mod unification;
pub mod morphism;
#[cfg(test)]
mod test;

204
src/morphism.rs Normal file
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@ -0,0 +1,204 @@
use {
crate::{
TypeTerm, TypeID,
unification::UnificationProblem,
},
std::collections::HashMap
};
//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\
pub struct MorphismType {
pub src_type: TypeTerm,
pub dst_type: TypeTerm,
}
pub struct MorphismBase<Morphism: Clone> {
morphisms: Vec< (MorphismType, Morphism) >,
list_typeid: TypeID
}
//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\
impl MorphismType {
fn normalize(self) -> Self {
MorphismType {
src_type: self.src_type.normalize(),
dst_type: self.dst_type.normalize()
}
}
}
//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\
impl<Morphism: Clone> MorphismBase<Morphism> {
pub fn new() -> Self {
MorphismBase {
morphisms: Vec::new(),
// FIXME: magic number
list_typeid: TypeID::Fun(10)
}
}
pub fn add_morphism(&mut self, morph_type: MorphismType, morphism: Morphism) {
self.morphisms.push( (morph_type.normalize(), morphism) );
}
pub fn enum_morphisms(&self, src_type: &TypeTerm)
-> Vec< (HashMap<TypeID, TypeTerm>, TypeTerm) >
{
let mut dst_types = Vec::new();
// first enumerate all "direct" morphisms,
for (ty,m) in self.morphisms.iter() {
if let Ok(σ) = crate::unification::unify(
&ty.src_type,
&src_type.clone().normalize()
) {
let dst_type =
ty.dst_type.clone()
.apply_substitution(
&|x| σ.get(x).cloned()
)
.clone();
dst_types.push( (σ, dst_type) );
}
}
// ..then all "list-map" morphisms.
// Check if we have a List type, and if so, see what the Item type is
// TODO: function for generating fresh variables
let item_variable = TypeID::Var(100);
if let Ok(σ) = crate::unification::unify(
&TypeTerm::App(vec![
TypeTerm::TypeID(self.list_typeid),
TypeTerm::TypeID(item_variable)
]),
&src_type.clone().param_normalize(),
) {
let src_item_type = σ.get(&item_variable).unwrap().clone();
for (γ, dst_item_type) in self.enum_morphisms( &src_item_type ) {
let dst_type =
TypeTerm::App(vec![
TypeTerm::TypeID(self.list_typeid),
dst_item_type.clone()
.apply_substitution(
&|x| γ.get(x).cloned()
).clone()
]).normalize();
dst_types.push( (γ.clone(), dst_type) );
}
}
dst_types
}
pub fn enum_morphisms_with_subtyping(&self, src_type: &TypeTerm)
-> Vec< (TypeTerm, TypeTerm) >
{
let mut src_lnf = src_type.clone().get_lnf_vec();
let mut halo_lnf = vec![];
let mut dst_types = Vec::new();
while src_lnf.len() > 0 {
let src_type = TypeTerm::Ladder( src_lnf.clone() );
let halo_type = TypeTerm::Ladder( halo_lnf.clone() );
for (σ, t) in self.enum_morphisms( &src_type ) {
dst_types.push(
(halo_type.clone()
.apply_substitution(
&|x| σ.get(x).cloned()
).clone(),
t.clone()
.apply_substitution(
&|x| σ.get(x).cloned()
).clone()
)
);
}
// continue with next supertype
halo_lnf.push(src_lnf.remove(0));
}
dst_types
}
/* performs DFS to find a morphism-path for a given type
* will return the first matching path, not the shortest
*/
pub fn find_morphism_path(&self, ty: MorphismType)
-> Option< Vec<TypeTerm> >
{
let ty = ty.normalize();
let mut visited = Vec::new();
let mut queue = vec![
vec![ ty.src_type.clone().normalize() ]
];
while let Some(current_path) = queue.pop() {
let current_type = current_path.last().unwrap();
if ! visited.contains( current_type ) {
visited.push( current_type.clone() );
for (h, t) in self.enum_morphisms_with_subtyping(&current_type) {
let tt = TypeTerm::Ladder( vec![ h, t ] ).normalize();
if ! visited.contains( &tt ) {
let unification_result = crate::unification::unify(&tt, &ty.dst_type);
let mut new_path = current_path.clone();
new_path.push( tt );
if let Ok(σ) = unification_result {
new_path = new_path.into_iter().map(
|mut t: TypeTerm| t.apply_substitution(&|x| σ.get(x).cloned()).clone()
).collect::<Vec<TypeTerm>>();
return Some(new_path);
} else {
queue.push( new_path );
}
}
}
}
}
None
}
pub fn find_morphism(&self, ty: &MorphismType)
-> Option< Morphism > {
// TODO
None
}
pub fn find_list_map_morphism(&self, item_ty: &MorphismType)
-> Option< Morphism > {
// TODO
None
}
pub fn find_morphism_with_subtyping(&self, ty: &MorphismType)
-> Option<( Morphism, TypeTerm, HashMap<TypeID, TypeTerm> )> {
// TODO
None
}
}
//<<<<>>>><<>><><<>><<<*>>><<>><><<>><<<<>>>>\\