merge(glittershark/achilles): Subtree import at 'b93268085a'

Imported from https://github.com/glittershark/achilles/

git-subtree-dir: users/glittershark/achilles
git-subtree-mainline: 4d193f2395
git-subtree-split: b93268085a
Change-Id: I64a583b454bbe03e20358ad7808939a4cbc212ba

users/glittershark/achilles/src/commands/check.rs

@@ -0,0 +1,39 @@
+use clap::Clap;
+use std::path::PathBuf;
+
+use crate::ast::Type;
+use crate::{parser, tc, Result};
+
+/// Typecheck a file or expression
+#[derive(Clap)]
+pub struct Check {
+    /// File to check
+    path: Option<PathBuf>,
+
+    /// Expression to check
+    #[clap(long, short = 'e')]
+    expr: Option<String>,
+}
+
+fn run_expr(expr: String) -> Result<Type<'static>> {
+    let (_, parsed) = parser::expr(&expr)?;
+    let hir_expr = tc::typecheck_expr(parsed)?;
+    Ok(hir_expr.type_().to_owned())
+}
+
+fn run_path(path: PathBuf) -> Result<Type<'static>> {
+    todo!()
+}
+
+impl Check {
+    pub fn run(self) -> Result<()> {
+        let type_ = match (self.path, self.expr) {
+            (None, None) => Err("Must specify either a file or expression to check".into()),
+            (Some(_), Some(_)) => Err("Cannot specify both a file and expression to check".into()),
+            (None, Some(expr)) => run_expr(expr),
+            (Some(path), None) => run_path(path),
+        }?;
+        println!("type: {}", type_);
+        Ok(())
+    }
+}