Align output of `tx simulate` with other Aiken's commands.

And also return a structured output as JSON, so it's more easily used
  by other tools.

  ```
       Parsing script context
    Simulating 78ec148ea647cf9969446891af31939c5d57b275a2455706782c6183ef0b62f1
      Redeemer Spend → 0

  {"mem":151993,"cpu":58180696}
  ```

crates/aiken/src/cmd/tx/simulate.rs

@@ -1,11 +1,11 @@
 use miette::IntoDiagnostic;
+use owo_colors::OwoColorize;
 use pallas_primitives::{
-    babbage::{TransactionInput, TransactionOutput},
+    babbage::{Redeemer, TransactionInput, TransactionOutput},
     Fragment,
 };
 use pallas_traverse::{Era, MultiEraTx};
-use std::fs;
-use std::path::PathBuf;
+use std::{fmt, fs, path::PathBuf, process};
 use uplc::{
     machine::cost_model::ExBudget,
     tx::{
@@ -54,6 +54,8 @@ pub fn exec(
         zero_slot,
     }: Args,
 ) -> miette::Result<()> {
+    eprintln!("{} script context", "      Parsing".bold().purple(),);
+
     let (tx_bytes, inputs_bytes, outputs_bytes) = if cbor {
         (
             fs::read(input).into_diagnostic()?,
@@ -76,6 +78,8 @@ pub fn exec(
         .or_else(|_| MultiEraTx::decode(Era::Alonzo, &tx_bytes))
         .into_diagnostic()?;
 
+    eprintln!("{} {}", "   Simulating".bold().purple(), tx.hash());
+
     let inputs = Vec::<TransactionInput>::decode_fragment(&inputs_bytes).unwrap();
     let outputs = Vec::<TransactionOutput>::decode_fragment(&outputs_bytes).unwrap();
 
@@ -88,8 +92,6 @@ pub fn exec(
         })
         .collect();
 
-    println!("Simulating: {}", tx.hash());
-
     if let Some(tx_babbage) = tx.as_babbage() {
         let slot_config = SlotConfig {
             zero_time,
@@ -97,13 +99,27 @@ pub fn exec(
             slot_length,
         };
 
-        let result =
-            tx::eval_phase_two(tx_babbage, &resolved_inputs, None, None, &slot_config, true);
+        let with_redeemer = |redeemer: &Redeemer| {
+            println!(
+                "{} {:?} → {}",
+                "     Redeemer".bold().purple(),
+                redeemer.tag,
+                redeemer.index
+            )
+        };
+
+        let result = tx::eval_phase_two(
+            tx_babbage,
+            &resolved_inputs,
+            None,
+            None,
+            &slot_config,
+            true,
+            with_redeemer,
+        );
 
         match result {
             Ok(redeemers) => {
-                println!("\nTotal Budget Used\n-----------------\n");
-
                 let total_budget_used =
                     redeemers
                         .iter()
@@ -112,11 +128,16 @@ pub fn exec(
                             cpu: accum.cpu + curr.ex_units.steps as i64,
                         });
 
-                println!("mem: {}", total_budget_used.mem);
-                println!("cpu: {}", total_budget_used.cpu);
+                println!(
+                    "\n{}",
+                    serde_json::to_string(&total_budget_used)
+                        .map_err(|_| fmt::Error)
+                        .into_diagnostic()?
+                );
             }
             Err(err) => {
-                eprintln!("\nError\n-----\n\n{err}\n");
+                eprintln!("{} {}", "        Error".bold().red(), err.red());
+                process::exit(1);
             }
         }
     }

crates/uplc/src/machine/cost_model.rs

@@ -18,7 +18,7 @@ macro_rules! hashmap {
 }
 
 /// Can be negative
-#[derive(Debug, Clone, PartialEq, Eq, Copy)]
+#[derive(Debug, Clone, PartialEq, Eq, Copy, serde::Serialize)]
 pub struct ExBudget {
     pub mem: i64,
     pub cpu: i64,

crates/uplc/src/tx.rs

@@ -35,6 +35,7 @@ pub fn eval_phase_two(
     initial_budget: Option<&ExBudget>,
     slot_config: &SlotConfig,
     run_phase_one: bool,
+    with_redeemer: fn(&Redeemer) -> (),
 ) -> Result<Vec<Redeemer>, Error> {
     let redeemers = tx.transaction_witness_set.redeemer.as_ref();
 
@@ -52,6 +53,8 @@ pub fn eval_phase_two(
             let mut remaining_budget = *initial_budget.unwrap_or(&ExBudget::default());
 
             for redeemer in rs.iter() {
+                with_redeemer(redeemer);
+
                 let redeemer = eval::eval_redeemer(
                     tx,
                     utxos,
@@ -87,6 +90,7 @@ pub fn eval_phase_two_raw(
     initial_budget: (u64, u64),
     slot_config: (u64, u64, u32),
     run_phase_one: bool,
+    with_redeemer: fn(&Redeemer) -> (),
 ) -> Result<Vec<Vec<u8>>, Error> {
     let multi_era_tx = MultiEraTx::decode(Era::Babbage, tx_bytes)
         .or_else(|_| MultiEraTx::decode(Era::Alonzo, tx_bytes))?;
@@ -122,6 +126,7 @@ pub fn eval_phase_two_raw(
                 Some(&budget),
                 &sc,
                 run_phase_one,
+                with_redeemer,
             ) {
                 Ok(redeemers) => Ok(redeemers
                     .iter()

crates/uplc/src/tx/tests.rs

@@ -246,6 +246,7 @@ fn test_eval() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -516,6 +517,7 @@ fn test_eval_1() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -621,6 +623,7 @@ fn test_eval_2() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -885,6 +888,7 @@ fn test_eval_3() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -987,6 +991,7 @@ fn test_eval_4() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .is_err());
         }
@@ -1069,6 +1074,7 @@ fn test_eval_5() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -1173,6 +1179,7 @@ fn test_eval_6() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -1277,6 +1284,7 @@ fn test_eval_7() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -1532,6 +1540,7 @@ fn test_eval_8() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
 
@@ -1632,6 +1641,7 @@ fn eval_missing_redeemer() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .unwrap();
         }
@@ -1711,6 +1721,7 @@ fn eval_extraneous_redeemer() {
                 Some(&initial_budget),
                 &slot_config,
                 false,
+                |_| (),
             )
             .is_err());
         }