feat: impl ifThenElse kinda

Co-authored-by: Kasey White <kwhitemsg@gmail.com>

add_integers.uplc

@@ -1,4 +1,4 @@
 (program
   1.0.0
-  [ (force (builtin ifThenElse)) (con bool True) (con integer 1) (con string "yo") ]
+  [ (builtin ifThenElse) (con bool True) (con integer 1) (con string "yo") ]
 )

crates/cli/src/main.rs

@@ -92,12 +92,21 @@ fn main() -> anyhow::Result<()> {
                     Program::<NamedDeBruijn>::try_from(prog)?
                 };
 
-                let term = program.eval()?;
+                let (term, cost, _logs) = program.eval();
 
+                match term {
+                    Ok(term) => {
                         let term: Term<Name> = term.try_into()?;
 
                         println!("{}", term.to_pretty());
                     }
+                    Err(err) => {
+                        eprintln!("{}", err);
+                    }
+                }
+
+                println!("Costs - memory: {} & cpu: {}", cost.mem, cost.cpu);
+            }
         },
     }
 

crates/uplc/src/ast.rs

@@ -4,7 +4,7 @@ use crate::{
     builtins::DefaultFunction,
     debruijn::{self, Converter},
     machine::{
-        cost_model::{ExBudget, CostModel},
+        cost_model::{CostModel, ExBudget},
         Machine,
     },
 };
@@ -406,11 +406,17 @@ impl From<Term<FakeNamedDeBruijn>> for Term<NamedDeBruijn> {
 }
 
 impl Program<NamedDeBruijn> {
-    pub fn eval(&self) -> Result<Term<NamedDeBruijn>, crate::machine::Error> {
+    pub fn eval(
+        &self,
+    ) -> (
+        Result<Term<NamedDeBruijn>, crate::machine::Error>,
+        ExBudget,
+        Vec<String>,
+    ) {
         let mut machine = Machine::new(CostModel::default(), ExBudget::default(), 200);
 
-        let (term, _, _) = machine.run(&self.term)?;
+        let term = machine.run(&self.term);
 
-        Ok(term)
+        (term, machine.ex_budget, machine.logs)
     }
 }

crates/uplc/src/machine.rs

@@ -14,11 +14,12 @@ use self::{cost_model::CostModel, runtime::BuiltinRuntime};
 
 pub struct Machine {
     costs: CostModel,
-    ex_budget: ExBudget,
+    pub ex_budget: ExBudget,
     frames: Vec<Context>,
     slippage: u32,
     env: Vec<Value>,
     unbudgeted_steps: [u32; 8],
+    pub logs: Vec<String>,
 }
 
 impl Machine {
@@ -30,20 +31,16 @@ impl Machine {
             frames: vec![Context::NoFrame],
             env: vec![],
             unbudgeted_steps: [0; 8],
+            logs: vec![],
         }
     }
 
-    pub fn run(
+    pub fn run(&mut self, term: &Term<NamedDeBruijn>) -> Result<Term<NamedDeBruijn>, Error> {
-        &mut self,
-        term: &Term<NamedDeBruijn>,
-    ) -> Result<(Term<NamedDeBruijn>, usize, Vec<String>), Error> {
         let startup_budget = self.costs.machine_costs.get(StepKind::StartUp);
 
         self.spend_budget(startup_budget)?;
 
-        let res = self.compute(term)?;
+        self.compute(term)
-
-        Ok((res, 0, vec![]))
     }
 
     fn compute(&mut self, term: &Term<NamedDeBruijn>) -> Result<Term<NamedDeBruijn>, Error> {
@@ -106,7 +103,7 @@ impl Machine {
     }
 
     fn return_compute(&mut self, value: Value) -> Result<Term<NamedDeBruijn>, Error> {
-        // TODO: avoid unwrap if possible and just return an err when None
+        // avoid unwrap if possible and just return an err when None
         // but honestly it should never be empty anyways because Machine
         // is initialized with `Context::NoFrame`.
         let frame = self.frames.last().cloned().unwrap();
@@ -197,7 +194,9 @@ impl Machine {
         match value {
             Value::Delay(body) => self.compute(&body),
             Value::Builtin { fun, term, runtime } => {
-                let force_term = Term::Force(Box::new(term));
+                let force_term = Term::Force(Box::new(dbg!(term)));
+
+                if runtime.is_all() {}
                 println!("{:#?}", runtime);
                 todo!()
             }
@@ -342,9 +341,14 @@ impl Value {
         matches!(self, Value::Con(Constant::Integer(_)))
     }
 
+    pub fn is_bool(&self) -> bool {
+        matches!(self, Value::Con(Constant::Bool(_)))
+    }
+
     pub fn to_ex_mem(&self) -> i64 {
         match self {
-            Value::Con(_) => todo!(),
+            // TODO: this is not 1
+            Value::Con(_) => 1,
             Value::Delay(_) => 1,
             Value::Lambda { .. } => 1,
             Value::Builtin { .. } => 1,

crates/uplc/src/machine/cost_model.rs

@@ -569,7 +569,18 @@ impl BuiltinCosts {
             DefaultFunction::EqualsString => todo!(),
             DefaultFunction::EncodeUtf8 => todo!(),
             DefaultFunction::DecodeUtf8 => todo!(),
-            DefaultFunction::IfThenElse => todo!(),
+            DefaultFunction::IfThenElse => ExBudget {
+                mem: self.if_then_else.mem.cost(
+                    args[0].to_ex_mem(),
+                    args[1].to_ex_mem(),
+                    args[2].to_ex_mem(),
+                ),
+                cpu: self.if_then_else.cpu.cost(
+                    args[0].to_ex_mem(),
+                    args[1].to_ex_mem(),
+                    args[2].to_ex_mem(),
+                ),
+            },
             DefaultFunction::ChooseUnit => todo!(),
             DefaultFunction::Trace => todo!(),
             DefaultFunction::FstPair => todo!(),

crates/uplc/src/machine/runtime.rs

@@ -48,12 +48,16 @@ impl BuiltinRuntime {
         self.args.len() == self.fun.arity()
     }
 
+    pub fn is_all(&self) -> bool {
+        self.args.is_empty()
+    }
+
     pub fn call(&self) -> Result<Value, Error> {
         self.fun.call(&self.args)
     }
 
     pub fn push(&mut self, arg: Value) -> Result<(), Error> {
-        self.fun.check_type(&arg)?;
+        self.fun.check_type(&arg, &self.args)?;
 
         self.args.push(arg);
 
@@ -102,7 +106,7 @@ impl DefaultFunction {
             DefaultFunction::EqualsString => todo!(),
             DefaultFunction::EncodeUtf8 => todo!(),
             DefaultFunction::DecodeUtf8 => todo!(),
-            DefaultFunction::IfThenElse => todo!(),
+            DefaultFunction::IfThenElse => 3,
             DefaultFunction::ChooseUnit => todo!(),
             DefaultFunction::Trace => todo!(),
             DefaultFunction::FstPair => todo!(),
@@ -131,7 +135,11 @@ impl DefaultFunction {
         }
     }
 
-    pub fn check_type(&self, arg: &Value) -> Result<(), Error> {
+    pub fn force_count() -> i32 {
+        3
+    }
+
+    pub fn check_type(&self, arg: &Value, args: &[Value]) -> Result<(), Error> {
         match self {
             DefaultFunction::AddInteger => {
                 if arg.is_integer() {
@@ -167,7 +175,17 @@ impl DefaultFunction {
             DefaultFunction::EqualsString => todo!(),
             DefaultFunction::EncodeUtf8 => todo!(),
             DefaultFunction::DecodeUtf8 => todo!(),
-            DefaultFunction::IfThenElse => todo!(),
+            DefaultFunction::IfThenElse => {
+                if args.is_empty() {
+                    if arg.is_bool() {
+                        return Ok(());
+                    } else {
+                        todo!("type error")
+                    }
+                }
+
+                Ok(())
+            }
             DefaultFunction::ChooseUnit => todo!(),
             DefaultFunction::Trace => todo!(),
             DefaultFunction::FstPair => todo!(),
@@ -237,7 +255,16 @@ impl DefaultFunction {
             DefaultFunction::EqualsString => todo!(),
             DefaultFunction::EncodeUtf8 => todo!(),
             DefaultFunction::DecodeUtf8 => todo!(),
-            DefaultFunction::IfThenElse => todo!(),
+            DefaultFunction::IfThenElse => match args[0] {
+                Value::Con(Constant::Bool(condition)) => {
+                    if condition {
+                        Ok(args[1].clone())
+                    } else {
+                        Ok(args[2].clone())
+                    }
+                }
+                _ => todo!("handle error"),
+            },
             DefaultFunction::ChooseUnit => todo!(),
             DefaultFunction::Trace => todo!(),
             DefaultFunction::FstPair => todo!(),