Document 'export' and provide better errors on module not found.

crates/aiken-lang/src/tipo/error.rs

@@ -1820,7 +1820,7 @@ pub enum UnknownRecordFieldSituation {
     FunctionCall,
 }
 
-fn format_suggestion(sample: &UntypedExpr) -> String {
+pub fn format_suggestion(sample: &UntypedExpr) -> String {
     Formatter::new()
         .expr(sample, false)
         .to_pretty_string(70)

crates/aiken-project/src/error.rs

@@ -128,6 +128,12 @@ pub enum Error {
     #[error("I couldn't find any exportable function named '{name}' in module '{module}'.")]
     ExportNotFound { module: String, name: String },
 
+    #[error("No such module '{module}' found in the project.")]
+    ModuleNotFound {
+        module: String,
+        known_modules: Vec<String>,
+    },
+
     #[error("I located conditional modules under 'env', but no default one!")]
     NoDefaultEnvironment,
 }
@@ -199,6 +205,7 @@ impl ExtraData for Error {
             | Error::MoreThanOneValidatorFound { .. }
             | Error::Module { .. }
             | Error::NoDefaultEnvironment { .. }
+            | Error::ModuleNotFound { .. }
             | Error::ExportNotFound { .. } => None,
             Error::Type { error, .. } => error.extra_data(),
         }
@@ -227,6 +234,7 @@ impl GetSource for Error {
             | Error::MalformedStakeAddress { .. }
             | Error::NoValidatorNotFound { .. }
             | Error::MoreThanOneValidatorFound { .. }
+            | Error::ModuleNotFound { .. }
             | Error::ExportNotFound { .. }
             | Error::NoDefaultEnvironment { .. }
             | Error::Module { .. } => None,
@@ -259,6 +267,7 @@ impl GetSource for Error {
             | Error::NoValidatorNotFound { .. }
             | Error::NoDefaultEnvironment { .. }
             | Error::MoreThanOneValidatorFound { .. }
+            | Error::ModuleNotFound { .. }
             | Error::ExportNotFound { .. }
             | Error::Module { .. } => None,
             Error::TomlLoading { src, .. } | Error::Parse { src, .. } | Error::Type { src, .. } => {
@@ -313,6 +322,7 @@ impl Diagnostic for Error {
             Error::NoValidatorNotFound { .. } => None,
             Error::MoreThanOneValidatorFound { .. } => None,
             Error::ExportNotFound { .. } => None,
+            Error::ModuleNotFound { .. } => None,
             Error::NoDefaultEnvironment { .. } => None,
             Error::Module(e) => e.code().map(boxed),
         }
@@ -347,6 +357,14 @@ impl Diagnostic for Error {
             Error::ZipExtract(_) => None,
             Error::JoinError(_) => None,
             Error::ExportNotFound { .. } => None,
+            Error::ModuleNotFound { known_modules, .. } => Some(Box::new(format!(
+                "I know about the following modules:\n{}",
+                known_modules
+                    .iter()
+                    .map(|s| format!("─▶ {}", s.if_supports_color(Stdout, |s| s.purple())))
+                    .collect::<Vec<_>>()
+                    .join("\n")
+            ))),
             Error::UnknownPackageVersion { .. } => Some(Box::new(
                 "Perhaps, double-check the package repository and version?",
             )),
@@ -419,6 +437,7 @@ impl Diagnostic for Error {
             Error::NoValidatorNotFound { .. } => None,
             Error::MoreThanOneValidatorFound { .. } => None,
             Error::NoDefaultEnvironment { .. } => None,
+            Error::ModuleNotFound { .. } => None,
             Error::Module(e) => e.labels(),
         }
     }
@@ -428,6 +447,7 @@ impl Diagnostic for Error {
             Error::DuplicateModule { .. } => None,
             Error::FileIo { .. } => None,
             Error::ImportCycle { .. } => None,
+            Error::ModuleNotFound { .. } => None,
             Error::ExportNotFound { .. } => None,
             Error::Blueprint(e) => e.source_code(),
             Error::NoDefaultEnvironment { .. } => None,
@@ -456,6 +476,7 @@ impl Diagnostic for Error {
             Error::DuplicateModule { .. } => None,
             Error::FileIo { .. } => None,
             Error::ImportCycle { .. } => None,
+            Error::ModuleNotFound { .. } => None,
             Error::ExportNotFound { .. } => None,
             Error::Blueprint(e) => e.url(),
             Error::Parse { .. } => None,
@@ -483,6 +504,7 @@ impl Diagnostic for Error {
         match self {
             Error::DuplicateModule { .. } => None,
             Error::FileIo { .. } => None,
+            Error::ModuleNotFound { .. } => None,
             Error::ExportNotFound { .. } => None,
             Error::Blueprint(e) => e.related(),
             Error::ImportCycle { .. } => None,

crates/aiken-project/src/lib.rs

@@ -534,13 +534,20 @@ where
     }
 
     pub fn export(&self, module: &str, name: &str, tracing: Tracing) -> Result<Export, Error> {
-        self.checked_modules
-            .get(module)
-            .and_then(|checked_module| {
-                checked_module.ast.definitions().find_map(|def| match def {
-                    Definition::Fn(func) if func.name == name => Some((checked_module, func)),
-                    _ => None,
-                })
+        let checked_module =
+            self.checked_modules
+                .get(module)
+                .ok_or_else(|| Error::ModuleNotFound {
+                    module: module.to_string(),
+                    known_modules: self.checked_modules.keys().cloned().collect(),
+                })?;
+
+        checked_module
+            .ast
+            .definitions()
+            .find_map(|def| match def {
+                Definition::Fn(func) if func.name == name => Some((checked_module, func)),
+                _ => None,
             })
             .map(|(checked_module, func)| {
                 let mut generator = self.new_generator(tracing);

crates/aiken/src/cmd/export.rs

@@ -4,6 +4,8 @@ use aiken_project::{options::Options, watch::with_project};
 use std::path::PathBuf;
 
 #[derive(clap::Args)]
+/// Export a function as a standalone UPLC program. Arguments to the function can be applied using
+/// `aiken apply`.
 pub struct Args {
     /// Path to project
     directory: Option<PathBuf>,