♻️ Fix compiler warnings

semver: chore

src/main.rs

@@ -11,7 +11,7 @@ pub mod parser;
 
 const INPUT: &str = "
 fn main() {
-    let a = |a ~ int| a * a;
+    let a = |a ~ int| { 1 + 1; a };
 
     let b = a;
 

src/parser/expression/mod.rs

@@ -113,7 +113,7 @@ pub fn call<'de>(
 }
 
 pub fn lambda<'de>(parser: &mut Parser<'de>) -> Result<Expression<'de>> {
-    let pipe = parser
+    parser
         .lexer
         .expect(TokenKind::Pipe, "expected a pipe before lambda arguments")?;
 

src/parser/typechecker/mod.rs

@@ -2,7 +2,6 @@ use super::ast::{untyped, Type, TypeValue};
 use crate::parser::ast::CombineSpan;
 use environment::Environment;
 use miette::{MietteDiagnostic, Result, SourceSpan};
-use std::{borrow::Cow, collections::HashMap};
 
 mod environment;
 #[cfg(test)]