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pub mod util;
pub mod display;
pub mod check;
pub mod subst;
use crate::sexp::SExp;
#[derive(Clone,Debug,PartialEq)]
pub enum Type {
Integer,
Boolean,
Arrow(Box<Type>, Box<Type>),
List(Vec<Type>),
/// Type for generics
/// and also error messages
/// with unknown types
VarType(String),
}
#[derive(Debug,PartialEq)]
pub enum TypeError {
UndefinedVariable(String),
UnboundGeneric(String),
InvalidOperator {
operator: SExp,
expected: Type,
found: Type,
},
InvalidArgList {
arglist: SExp,
expected: Type,
found: Type,
},
ArgumentsDontMatchGeneric {
argtype: Type,
generictype: Type,
},
OtherError
}
use Type::*;
impl Type {
/// Tests if the type has no variable types.
///
/// **Examples**
/// ```rust
/// use myslip::r#type::{*, Type::*, TypeError::*, util::*};
///
/// assert_eq!(Integer.is_concrete(), Ok(()));
/// assert_eq!(Boolean.is_concrete(), Ok(()));
/// assert_eq!(
/// VarType("a".to_string()).is_concrete(),
/// Err("a".to_string())
/// );
///
/// assert_eq!(arr(Integer, Integer).is_concrete(), Ok(()));
/// assert_eq!(arr(Integer, Boolean).is_concrete(), Ok(()));
/// assert_eq!(
/// arr(VarType("b".to_string()), Integer).is_concrete(),
/// Err("b".to_string())
/// );
///
/// assert_eq!(
/// List(vec![Integer, Boolean, arr(Integer, Integer)]).is_concrete(),
/// Ok(())
/// );
/// assert_eq!(
/// List(vec![Integer, VarType("a".to_string()), Integer])
/// .is_concrete(),
/// Err("a".to_string())
/// );
/// ```
pub fn is_concrete(&self) -> Result<(), String> {
match self {
Integer => Ok(()),
Boolean => Ok(()),
Arrow(a, b) => b.is_concrete().and_then(|_ok| a.is_concrete()),
List(v) => {
let mut res = Ok(());
for t in v {
res = res.and_then(|_ok| t.is_concrete());
}
res
},
VarType(s) => Err(s.clone()),
}
}
}
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