feat: better errors for debruijn converter

crates/uplc/src/ast.rs

@@ -1,4 +1,9 @@
-use crate::{builtins::DefaultFunction, debruijn::Converter};
+use std::fmt::Display;
+
+use crate::{
+    builtins::DefaultFunction,
+    debruijn::{self, Converter},
+};
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct Program<T> {
@@ -79,6 +84,12 @@ impl From<Unique> for isize {
     }
 }
 
+impl Display for Unique {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
 #[derive(Debug, Clone, PartialEq)]
 pub struct NamedDeBruijn {
     pub text: String,
@@ -122,7 +133,7 @@ impl From<DeBruijn> for NamedDeBruijn {
 }
 
 impl TryFrom<Program<Name>> for Program<NamedDeBruijn> {
-    type Error = String;
+    type Error = debruijn::Error;
 
     fn try_from(value: Program<Name>) -> Result<Self, Self::Error> {
         Ok(Program::<NamedDeBruijn> {
@@ -133,23 +144,19 @@ impl TryFrom<Program<Name>> for Program<NamedDeBruijn> {
 }
 
 impl TryFrom<Term<Name>> for Term<NamedDeBruijn> {
-    type Error = String;
+    type Error = debruijn::Error;
 
-    fn try_from(
-        value: Term<Name>,
-    ) -> Result<Self, <Term<NamedDeBruijn> as TryFrom<Term<Name>>>::Error> {
+    fn try_from(value: Term<Name>) -> Result<Self, debruijn::Error> {
         let mut converter = Converter::new();
 
-        let term = converter
-            .name_to_named_debruijn(value)
-            .map_err(|err| err.to_string())?;
+        let term = converter.name_to_named_debruijn(value)?;
 
         Ok(term)
     }
 }
 
 impl TryFrom<Program<Name>> for Program<DeBruijn> {
-    type Error = String;
+    type Error = debruijn::Error;
 
     fn try_from(value: Program<Name>) -> Result<Self, Self::Error> {
         Ok(Program::<DeBruijn> {
@@ -160,21 +167,19 @@ impl TryFrom<Program<Name>> for Program<DeBruijn> {
 }
 
 impl TryFrom<Term<Name>> for Term<DeBruijn> {
-    type Error = String;
+    type Error = debruijn::Error;
 
-    fn try_from(value: Term<Name>) -> Result<Self, <Term<DeBruijn> as TryFrom<Term<Name>>>::Error> {
+    fn try_from(value: Term<Name>) -> Result<Self, debruijn::Error> {
         let mut converter = Converter::new();
 
-        let term = converter
-            .name_to_debruijn(value)
-            .map_err(|err| err.to_string())?;
+        let term = converter.name_to_debruijn(value)?;
 
         Ok(term)
     }
 }
 
 impl TryFrom<Program<NamedDeBruijn>> for Program<Name> {
-    type Error = String;
+    type Error = debruijn::Error;
 
     fn try_from(value: Program<NamedDeBruijn>) -> Result<Self, Self::Error> {
         Ok(Program::<Name> {
@@ -185,16 +190,12 @@ impl TryFrom<Program<NamedDeBruijn>> for Program<Name> {
 }
 
 impl TryFrom<Term<NamedDeBruijn>> for Term<Name> {
-    type Error = String;
+    type Error = debruijn::Error;
 
-    fn try_from(
-        value: Term<NamedDeBruijn>,
-    ) -> Result<Self, <Term<Name> as TryFrom<Term<NamedDeBruijn>>>::Error> {
+    fn try_from(value: Term<NamedDeBruijn>) -> Result<Self, debruijn::Error> {
         let mut converter = Converter::new();
 
-        let term = converter
-            .named_debruijn_to_name(value)
-            .map_err(|err| err.to_string())?;
+        let term = converter.named_debruijn_to_name(value)?;
 
         Ok(term)
     }
@@ -218,7 +219,7 @@ impl From<Term<NamedDeBruijn>> for Term<DeBruijn> {
 }
 
 impl TryFrom<Program<DeBruijn>> for Program<Name> {
-    type Error = String;
+    type Error = debruijn::Error;
 
     fn try_from(value: Program<DeBruijn>) -> Result<Self, Self::Error> {
         Ok(Program::<Name> {
@@ -229,16 +230,12 @@ impl TryFrom<Program<DeBruijn>> for Program<Name> {
 }
 
 impl TryFrom<Term<DeBruijn>> for Term<Name> {
-    type Error = String;
+    type Error = debruijn::Error;
 
-    fn try_from(
-        value: Term<DeBruijn>,
-    ) -> Result<Self, <Term<Name> as TryFrom<Term<DeBruijn>>>::Error> {
+    fn try_from(value: Term<DeBruijn>) -> Result<Self, debruijn::Error> {
         let mut converter = Converter::new();
 
-        let term = converter
-            .debruijn_to_name(value)
-            .map_err(|err| err.to_string())?;
+        let term = converter.debruijn_to_name(value)?;
 
         Ok(term)
     }

crates/uplc/src/debruijn.rs

@@ -1,10 +1,18 @@
 use std::collections::HashMap;
 
+use thiserror::Error;
+
 use crate::ast::{DeBruijn, Name, NamedDeBruijn, Term, Unique};
 
 #[derive(Debug, Copy, Clone)]
 struct Level(usize);
 
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("Free Unique: `{0}`")]
+    FreeUnique(Unique),
+}
+
 pub struct Converter {
     current_level: Level,
     levels: Vec<HashMap<Unique, Level>>,
@@ -21,7 +29,7 @@ impl Converter {
     pub fn name_to_named_debruijn(
         &mut self,
         term: Term<Name>,
-    ) -> anyhow::Result<Term<NamedDeBruijn>> {
+    ) -> Result<Term<NamedDeBruijn>, Error> {
         let converted_term = match term {
             Term::Var(Name { text, unique }) => Term::Var(NamedDeBruijn {
                 text,
@@ -65,7 +73,7 @@ impl Converter {
         Ok(converted_term)
     }
 
-    pub fn name_to_debruijn(&mut self, term: Term<Name>) -> anyhow::Result<Term<DeBruijn>> {
+    pub fn name_to_debruijn(&mut self, term: Term<Name>) -> Result<Term<DeBruijn>, Error> {
         let converted_term = match term {
             Term::Var(Name { unique, .. }) => Term::Var(self.get_index(unique)?),
             Term::Delay(term) => Term::Delay(Box::new(self.name_to_debruijn(*term)?)),
@@ -104,7 +112,7 @@ impl Converter {
     pub fn named_debruijn_to_name(
         &mut self,
         _term: Term<NamedDeBruijn>,
-    ) -> anyhow::Result<Term<Name>> {
+    ) -> Result<Term<Name>, Error> {
         todo!()
     }
 
@@ -130,7 +138,7 @@ impl Converter {
         }
     }
 
-    pub fn debruijn_to_name(&mut self, _term: Term<DeBruijn>) -> anyhow::Result<Term<Name>> {
+    pub fn debruijn_to_name(&mut self, _term: Term<DeBruijn>) -> Result<Term<Name>, Error> {
         todo!()
     }
 
@@ -156,7 +164,7 @@ impl Converter {
         }
     }
 
-    fn get_index(&mut self, unique: Unique) -> anyhow::Result<DeBruijn> {
+    fn get_index(&mut self, unique: Unique) -> Result<DeBruijn, Error> {
         for scope in self.levels.iter().rev() {
             if let Some(found_level) = scope.get(&unique) {
                 let index = self.current_level.0 - found_level.0;
@@ -165,7 +173,7 @@ impl Converter {
             }
         }
 
-        anyhow::bail!("Free unique: {}", isize::from(unique))
+        Err(Error::FreeUnique(unique))
     }
 
     fn declare_unique(&mut self, unique: Unique) {