re-organize project

executor/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "executor"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+albireo = { path = "../albireo" }

executor/src/errors.rs

@@ -0,0 +1,22 @@
+use std::fmt;
+
+pub type Result<T> = std::result::Result<T, ExecutionError>;
+
+#[derive(Debug)]
+pub enum ExecutionError {
+  MainNotFound,
+  MainSignatureIncorrect,
+}
+
+impl std::error::Error for ExecutionError {}
+
+impl fmt::Display for ExecutionError {
+  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    match self {
+      ExecutionError::MainNotFound =>
+        write!(f, "main function not found"),
+      ExecutionError::MainSignatureIncorrect =>
+        write!(f, "main function signature is incorrect, expecting Fn([], T) for any output type T"),
+    }
+  }
+}

executor/src/lib.rs

@@ -0,0 +1,23 @@
+pub mod errors;
+
+use errors::{Result, ExecutionError};
+
+use albireo::{Expression, Type, Identifier, Module, Declaration};
+
+// TODO: accepting a module map not a module
+pub fn run_program(module: Module) -> Result<()> {
+    let main = module.declaration.get(&Identifier { name: "main".into() })
+        .ok_or(ExecutionError::MainNotFound)?;
+
+    // expecting main to be function receiving no parameter
+    if let Declaration::Variable(_, Type::Function(input, _), _) = main {
+        if input.len() != 0 {
+            return Err(ExecutionError::MainSignatureIncorrect)
+        }
+    } else {
+        return Err(ExecutionError::MainSignatureIncorrect)
+    };
+
+    println!("main {:?}", main);
+    Ok(())
+}