1 files changed, 0 insertions, 167 deletions
diff --git a/src/simple.rs b/src/simple.rs
index c67fe2e..8d87dbf 100644
--- a/src/simple.rs
+++ b/src/simple.rs
@@ -1,91 +1,4 @@
-// Simple bidirectional type checking
-
 use crate::ast::*;
-use std::collections::HashMap;
-
-pub fn check(context: &Context, expression: Expression, target: &Type) -> Result<(), String> {
-    match expression {
-        // fall through to inference mode
-        Expression::Annotation { expr, kind } => {
-            let result = infer(context, Expression::Annotation { expr, kind })?;
-            return match subtype(&result, &target) {
-                true => Ok(()),
-                false => Err(format!("inferred type {result} does not match target {target}"))
-            }
-        },
-        // Bt-CheckInfer
-        Expression::Constant { term } => match subtype(&convert(&term)?, &target) {
-            true => Ok(()),
-            false => Err(format!("constant is of wrong type, expected {target}"))
-            // false => Ok(()) // all our constants are Empty for now
-        },
-        // Bt-CheckInfer
-        Expression::Variable { id } => match context.get(&id) {
-            Some(term) if subtype(&convert(term)?, &target) => Ok(()),
-            Some(_) => Err(format!("variable {id} is of wrong type")),
-            None => Err(format!("failed to find variable {id} in context"))
-        },
-        // Bt-Abs
-        Expression::Abstraction { param, func } => match target {
-            Type::Function { from, to } => {
-                let mut context = context.clone();
-                context.insert(param, default(from)?);
-                return check(&context, *func, &to);
-            },
-            _ => Err(format!("attempting to check an abstraction with a non-function type {target}"))
-        },
-        // fall through to inference mode
-        Expression::Application { func, arg } => {
-            let result = &infer(context, Expression::Application { func, arg })?;
-            return match subtype(&result, &target) {
-                true => Ok(()),
-                false => Err(format!("inferred type {result} does not match {target}"))
-            }
-        },
-        // T-If
-        Expression::Conditional { if_cond, if_then, if_else } => {
-            check(context, *if_cond, &Type::Boolean)?;
-            check(context, *if_then, &target)?;
-            check(context, *if_else, &target)?;
-            return Ok(());
-        }
-    }
-}
-
-pub fn infer(context: &Context, expression: Expression) -> Result<Type, String> {
-    match expression {
-        // Bt-Ann
-        Expression::Annotation { expr, kind } => check(context, *expr, &kind).map(|x| kind),
-        // Bt-True / Bt-False / etc
-        Expression::Constant { term } => convert(&term),
-        // Bt-Var
-        Expression::Variable { id } => match context.get(&id) {
-            Some(term) => infer(&Context::new(), Expression::Constant { term: term.clone() }),
-            None => Err(format!("failed to find variable in context {context:?}"))
-        },
-        // Bt-App
-        Expression::Application { func, arg } => match infer(context, *func)? {
-            Type::Function { from, to } => check(context, *arg, &*from).map(|x| *to),
-            _ => Err(format!("application abstraction is not a function type"))
-        },
-        // inference from an abstraction is always an error
-        // we could try and infer the func without adding the parameter to scope:
-        // but this is overwhelmingly likely to be an error, so just report it now.
-        Expression::Abstraction { param, func } =>
-            Err(format!("attempting to infer from an abstraction")),
-        // idk
-        Expression::Conditional { if_cond, if_then, if_else } => {
-            check(context, *if_cond, &Type::Boolean)?;
-            let if_then = infer(context, *if_then)?;
-            let if_else = infer(context, *if_else)?;
-            if subtype(&if_then, &if_else) && subtype(&if_else, &if_then) {
-                Ok(if_then) // fixme: should be the join
-            } else {
-                Err(format!("if clauses of different types: {if_then} and {if_else}"))
-            }
-        }
-    }
-}
 
 /// Evaluates an expression given a context (of variables) to a term, or fails.
 pub fn execute(context: &Context, expression: Expression) -> Result<Term, String> {
@@ -117,83 +30,3 @@ pub fn execute(context: &Context, expression: Expression) -> Result<Term, String
     }
 }
 
-/// The subtyping relation between any two types.
-pub fn subtype(is: &Type, of: &Type) -> bool {
-    match (is, of) {
-        (Type::Record(is_fields), Type::Record(of_fields)) => {
-            // width, depth, and permutation
-            for (key, of_value) in of_fields {
-                match is_fields.get(key) {
-                    Some(is_value) => {
-                        if !subtype(is_value, of_value) {
-                            return false;
-                        }
-                    }
-                    None => return false
-                }
-            }
-            return true;
-        },
-        (Type::Function { from: is_from, to: is_to },
-         Type::Function { from: of_from, to: of_to }) => {
-            subtype(of_from, is_from) && subtype(is_to, of_to)
-        },
-        (Type::Natural, Type::Integer) => true, // obviously not, but let's pretend
-        (_, Type::Empty) => true,
-        (Type::Error, _) => true,
-        (_, _) if is == of => true,
-        (_, _) => false
-    }
-}
-
-/// Convert a term into its corresponding type.
-pub fn convert(term: &Term) -> Result<Type, String> {
-    match term {
-        Term::Unit() => Ok(Type::Unit),
-        Term::Boolean(_) => Ok(Type::Boolean),
-        Term::Natural(_) => Ok(Type::Natural),
-        Term::Integer(_) => Ok(Type::Integer),
-        Term::Float(_) => Ok(Type::Float),
-        Term::String { len, cap, data } => Ok(Type::String),
-        Term::Enum { val, data } => data.get(*val)
-            .ok_or_else(|| "enum value out of range!".to_string()).cloned(),
-        Term::Record(data) => {
-            let mut result = HashMap::new();
-            for (key, val) in data {
-                result.insert(key.clone(), convert(val)?);
-            }
-            return Ok(Type::Record(result));
-        },
-        Term::Function(func) => match infer(&Context::new(), *func.clone()) {
-            Ok(Type::Function { from, to }) => Ok(Type::Function { from, to }),
-            _ => Err("function term value not a function!".to_string())
-        }
-    }
-}
-
-/// Get the default value of a type. Throws an error if it doesn't exist.
-pub fn default(kind: &Type) -> Result<Term, String> {
-    match kind {
-        Type::Empty => Err("attempting to take the default term for empty".to_string()),
-        Type::Error => Err("attempting to take the default term for error".to_string()),
-        Type::Unit => Ok(Term::Unit()),
-        Type::Boolean => Ok(Term::Boolean(false)),
-        Type::Natural => Ok(Term::Natural(0)),
-        Type::Integer => Ok(Term::Integer(0)),
-        Type::Float => Ok(Term::Float(0.0)),
-        Type::String => Ok(Term::String { len: 0, cap: 0, data: vec!()}),
-        Type::Enum(data) => match data.len() {
-            0 => Err("attempting to get a default term of an enum with no variants!".to_string()),
-            _ => Ok(Term::Enum { val: 0, data: data.clone() })
-        },
-        Type::Record(data) => {
-            let mut result = HashMap::new();
-            for (key, val) in data {
-                result.insert(key.clone(), default(&val)?);
-            }
-            return Ok(Term::Record(result));
-        },
-        Type::Function { from, to } =>
-            Err("attempting to take the default term of a function type".to_string()),
-    }
-}