From 2acb82ca1a263f91934cc194da488939b55b4024 Mon Sep 17 00:00:00 2001
From: Folkert <folkert@folkertdev.nl>
Date: Wed, 18 Dec 2019 00:27:41 +0100
Subject: [PATCH] canonicalize annotations

---
 src/can/annotation.rs | 106 ++++++++++++++++++++++++++++++++++++++++++
 src/can/mod.rs        |   1 +
 2 files changed, 107 insertions(+)
 create mode 100644 src/can/annotation.rs

diff --git a/src/can/annotation.rs b/src/can/annotation.rs
new file mode 100644
index 0000000000..176c39ce28
--- /dev/null
+++ b/src/can/annotation.rs
@@ -0,0 +1,106 @@
+use crate::can::expr::Rigids;
+use crate::can::ident::Lowercase;
+use crate::collections::{ImMap, SendMap};
+use crate::parse::ast::{AssignedField, TypeAnnotation};
+use crate::subs::VarStore;
+use crate::types::Type;
+
+pub fn canonicalize_annotation(
+    annotation: &crate::parse::ast::TypeAnnotation,
+    var_store: &VarStore,
+) -> (Rigids, crate::types::Type) {
+    let mut ftv = ImMap::default();
+    let result = can_annotation_help(annotation, var_store, &mut ftv);
+
+    (ftv, result)
+}
+
+fn can_annotation_help(
+    annotation: &crate::parse::ast::TypeAnnotation,
+    var_store: &VarStore,
+    ftv: &mut Rigids,
+) -> (crate::types::Type) {
+    use crate::parse::ast::TypeAnnotation::*;
+
+    match annotation {
+        Function(argument_types, return_type) => {
+            let mut args = Vec::new();
+
+            for arg in *argument_types {
+                args.push(can_annotation_help(&arg.value, var_store, ftv));
+            }
+
+            let ret = can_annotation_help(&return_type.value, var_store, ftv);
+            Type::Function(args, Box::new(ret))
+        }
+        Apply(module_name, name, type_arguments) => {
+            let mut args = Vec::new();
+
+            for arg in *type_arguments {
+                args.push(can_annotation_help(&arg.value, var_store, ftv));
+            }
+
+            Type::Apply {
+                module_name: module_name.join(".").into(),
+                name: (*name).into(),
+                args,
+            }
+        }
+        BoundVariable(v) => {
+            // TODO register rigid var here
+            let var = var_store.fresh();
+            ftv.insert((*v).into(), Type::Variable(var));
+            Type::Variable(var)
+        }
+        Record(fields) => {
+            let mut field_types = SendMap::default();
+            for field in fields {
+                can_assigned_field(&field.value, var_store, ftv, &mut field_types);
+            }
+
+            // fragment variable is free in this case
+            let fragment_var = var_store.fresh();
+            let fragment_type = Type::Variable(fragment_var);
+
+            Type::Record(field_types, Box::new(fragment_type))
+        }
+        RecordFragment(fields, fragment) => {
+            let mut field_types = SendMap::default();
+            for field in fields {
+                can_assigned_field(&field.value, var_store, ftv, &mut field_types);
+            }
+
+            let fragment_type = can_annotation_help(&fragment.value, var_store, ftv);
+
+            Type::Record(field_types, Box::new(fragment_type))
+        }
+        SpaceBefore(nested, _) | SpaceAfter(nested, _) => {
+            can_annotation_help(nested, var_store, ftv)
+        }
+        Wildcard | Malformed(_) => {
+            let var = var_store.fresh();
+            Type::Variable(var)
+        }
+    }
+}
+
+fn can_assigned_field<'a>(
+    field: &AssignedField<'a, TypeAnnotation<'a>>,
+    var_store: &VarStore,
+    ftv: &mut Rigids,
+    field_types: &mut SendMap<Lowercase, Type>,
+) {
+    use crate::parse::ast::AssignedField::*;
+
+    match field {
+        LabeledValue(field_name, _, annotation) => {
+            let field_type = can_annotation_help(&annotation.value, var_store, ftv);
+            field_types.insert(Lowercase::from(field_name.value), field_type);
+        }
+        LabelOnly(_) => panic!("Illegal at the type level?"),
+        SpaceBefore(nested, _) | SpaceAfter(nested, _) => {
+            can_assigned_field(nested, var_store, ftv, field_types)
+        }
+        Malformed(_) => {}
+    }
+}
diff --git a/src/can/mod.rs b/src/can/mod.rs
index c26f7d00a9..1877fd4537 100644
--- a/src/can/mod.rs
+++ b/src/can/mod.rs
@@ -1,3 +1,4 @@
+pub mod annotation;
 pub mod def;
 pub mod env;
 pub mod expr;