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Use universal/existential type data structures

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This commit is contained in:
greg 2017-10-09 00:36:54 -07:00
parent f2c6556c2a
commit 4bcbf1854a
1 changed files with 20 additions and 10 deletions
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30
src/schala_lang/type_check.rs
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@ -48,7 +48,8 @@ impl SymbolTable {
}
fn lookup(&mut self, binding: &Rc<String>) -> Option<TypeVariable> {
use self::TypeVariable::*;
Some(Function(Box::new(Integer), Box::new(Boolean)))
use self::UVar::*;
Some(Univ(Function(Box::new(Univ(Integer)), Box::new(Univ(Boolean)))))
}
}
@ -68,8 +69,15 @@ impl TypeContext {
}
}
#[derive(Debug, PartialEq, Clone)]
pub enum TypeVariable {
Univ(UVar),
Exist(u64),
}
#[derive(Debug, PartialEq, Clone)]
pub enum UVar {
Integer,
Boolean,
Unit,
@ -80,16 +88,17 @@ pub enum TypeVariable {
impl TypeVariable {
fn from_anno(anno: &TypeName) -> TypeVariable {
use self::TypeVariable::*;
use self::UVar::*;
match anno {
&TypeName::Singleton { ref name, .. } => {
match name.as_ref().as_ref() {
"Int" => Integer,
"Bool" => Boolean,
_ => Bottom,
"Int" => Univ(Integer),
"Bool" => Univ(Boolean),
_ => Univ(Bottom),
}
},
_ => Bottom,
_ => Univ(Bottom),
}
}
}
@ -115,7 +124,7 @@ type TypeCheckResult = Result<TypeVariable, String>;
impl TypeContext {
pub fn type_check(&mut self, ast: &AST) -> TypeCheckResult {
let mut last = TypeVariable::Unit;
let mut last = TypeVariable::Univ(UVar::Unit);
for statement in ast.0.iter() {
match statement {
&Statement::Declaration(ref _decl) => {
@ -131,14 +140,15 @@ impl TypeContext {
fn infer(&mut self, expr: &Expression) -> TypeCheckResult {
use self::ExpressionType::*;
use self::TypeVariable::*;
Ok(match (&expr.0, &expr.1) {
(ref _t, &Some(ref anno)) => {
//TODO make this better,
TypeVariable::from_anno(anno)
},
(&IntLiteral(_), _) => TypeVariable::Integer,
(&BoolLiteral(_), _) => TypeVariable::Boolean,
(&IntLiteral(_), _) => Univ(UVar::Integer),
(&BoolLiteral(_), _) => Univ(UVar::Boolean),
(&Variable(ref name), _) => self.symbol_table
.lookup(name)
.ok_or(format!("Couldn't find {}", name))?,
@ -147,14 +157,14 @@ impl TypeContext {
let f_type = self.infer(&*f)?;
let arg_type = self.infer(arguments.get(0).unwrap())?; // TODO fix later
match f_type {
TypeVariable::Function(box t1, box ret_type) => {
Univ(UVar::Function(box t1, box ret_type)) => {
let _ = self.unify(&t1, &arg_type)?;
ret_type
},
_ => return Err(format!("Type error"))
}
},
_ => TypeVariable::Unit,
_ => Univ(UVar::Unit),
})
}