skeleton continues

src/nixcmd.rs

@@ -0,0 +1,27 @@
+#[allow(unused_imports)]
+use crate::prelude::*;
+
+#[derive(Debug, Clone, PartialEq, Hash)]
+pub(crate) struct NixEvalExpr<E, A> {
+    pub(crate) expr: E,
+    pub(crate) attrpath: A,
+}
+
+impl<E, A> NixEvalExpr<E, A>
+where
+    E: AsRef<OsStr>,
+    A: AsRef<OsStr>,
+{
+    pub(crate) fn into_command(self) -> Command {
+        let mut cmd = Command::new("nix-instantiate");
+        cmd.arg("--eval")
+            .arg("--json")
+            .arg("--strict")
+            .arg("--expr")
+            .arg(self.expr)
+            .arg("-A")
+            .arg(self.attrpath);
+
+        cmd
+    }
+}