fix: refined [x] to x conversion, think (not true) and (vector 1)

1 files changed, 7 insertions, 0 deletions

diff --git a/src/type/conversion.rs b/src/type/conversion.rs
index 844632f..ab858e6 100644
--- a/src/type/conversion.rs
+++ b/src/type/conversion.rs
@@ -12,6 +12,7 @@ impl Type {
     /// 1. (T T ... T T) -> (T ...)
     /// 2. self = concrete and other = variable type => self,
     /// 3. arrow types and lists are mapped
+    /// 4. makes [self] self if self == other
     pub fn convert(self, other: &Type) -> Result<Type, ()> {
 	let (ty, ctx) = self.convert_ctx(other)?;
 	let mut checks = HashMap::new();
@@ -83,6 +84,12 @@ impl Type {
 		Ok((vecof(convt), ctx))
 	    },
 
+	    // at the end, because it'd be nice to know in the
+	    // guard that the conversion from v to t2 works, and
+	    // if it doesn't, try something else, but now everyhting
+	    // has already been tried so this is safe
+	    (List(v), t2) if v.len() == 1 => v[0].clone().convert_ctx(t2),
+
 	    _ => Err(())
 	}
     }