2 files changed, 54 insertions, 7 deletions

diff --git a/src/compiler.rs b/src/compiler.rs
index bdc5901..588a9e9 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -1,6 +1,6 @@
 use std::path::{Path, PathBuf};
 use std::cell::RefCell;
-use std::collections::{HashMap, hash_map::Entry};
+use std::collections::{HashMap, HashSet, hash_map::Entry};
 use std::rc::Rc;
 
 use crate::{Blob, Block, Op, Prog, RustFunction, Type, Value};
@@ -1403,18 +1403,19 @@ impl Compiler {
     }
 
     fn parse_type(&mut self) -> Result<Type, ()> {
-        let mut tys = vec![self.parse_simple_type()?];
+        let mut tys = HashSet::new();
+        tys.insert(self.parse_simple_type()?);
         loop {
             match self.peek() {
                 Token::Questionmark => {
                     self.eat();
-                    tys.push(Type::Void);
+                    tys.insert(Type::Void);
                     return Ok(Type::Union(tys));
                 },
 
                 Token::Pipe => {
                     self.eat();
-                    tys.push(self.parse_simple_type()?);
+                    tys.insert(self.parse_simple_type()?);
                 },
 
                 _ => {
@@ -1423,7 +1424,7 @@ impl Compiler {
             }
         }
         if tys.len() == 1 {
-            Ok(tys[0].clone())
+            Ok(tys.iter().next().unwrap().clone())
         } else {
             Ok(Type::Union(tys))
         }
diff --git a/src/lib.rs b/src/lib.rs
index c085cca..6f63ad7 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,5 +1,5 @@
 use std::cell::RefCell;
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 use std::collections::hash_map::Entry;
 use std::fmt::Debug;
 use std::path::{Path, PathBuf};
@@ -86,12 +86,56 @@ pub enum Type {
     Bool,
     String,
     Tuple(Vec<Type>),
-    Union(Vec<Type>),
+    Union(HashSet<Type>),
     Function(Vec<Type>, Box<Type>),
     Blob(Rc<Blob>),
     Instance(Rc<Blob>),
 }
 
+impl Hash for Type {
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        match self {
+            Type::Void => 0,
+            Type::Unknown => 1,
+            Type::Int => 2,
+            Type::Float => 3,
+            Type::Bool => 4,
+            Type::String => 5,
+            Type::Tuple(ts) => {
+                for t in ts.iter() {
+                    t.hash(h);
+                }
+                6
+            }
+            Type::Union(ts) => {
+                for t in ts {
+                    t.hash(h);
+                }
+                7
+            }
+            Type::Function(args, ret) => {
+                ret.hash(h);
+                for t in args.iter() {
+                    t.hash(h);
+                }
+                8
+            }
+            Type::Blob(b) => {
+                for (_, t) in b.fields.values() {
+                    t.hash(h);
+                }
+                10
+            }
+            Type::Instance(b) => {
+                for (_, t) in b.fields.values() {
+                    t.hash(h);
+                }
+                11
+            }
+        }.hash(h);
+    }
+}
+
 impl PartialEq for Type {
     fn eq(&self, other: &Self) -> bool {
         match (self, other) {
@@ -115,6 +159,8 @@ impl PartialEq for Type {
     }
 }
 
+impl Eq for Type {}
+
 impl From<&Value> for Type {
     fn from(value: &Value) -> Type {
         match value {