From bf0202f74dd68eb6664d19c603cf69e97d5a16d7 Mon Sep 17 00:00:00 2001
From: Sahas Subramanian <sahas.subramanian@proton.me>
Date: Sat, 18 Nov 2023 14:26:22 +0100
Subject: [PATCH] Replace `let*` implementation with `let`

`let` was already functioning like `let*`, so now both the functions
have the `let*` behaviour.

And with this `let*` is no longer a macro that expands to nested
`let`s, but a special form that's faster to execute.
---
 src/builtin/functions/functions.rs |  5 +++-
 src/builtin/macros.rs              | 36 ------------------------
 tests/tests.rs                     | 44 +++++++++++++++---------------
 3 files changed, 26 insertions(+), 59 deletions(-)

diff --git a/src/builtin/functions/functions.rs b/src/builtin/functions/functions.rs
index d443cb7..209067c 100644
--- a/src/builtin/functions/functions.rs
+++ b/src/builtin/functions/functions.rs
@@ -15,6 +15,7 @@ use crate::{destruct_bind, list};
 use std::convert::TryInto;
 use std::rc::Rc;
 
+use tulisp_proc_macros::crate_add_func;
 use tulisp_proc_macros::{crate_fn, crate_fn_no_eval};
 
 pub(super) fn reduce_with(
@@ -203,7 +204,7 @@ pub(crate) fn add(ctx: &mut TulispContext) {
         Ok(value)
     }
 
-    #[crate_fn_no_eval(add_func = "ctx", name = "let")]
+    #[crate_fn_no_eval]
     fn impl_let(
         ctx: &mut TulispContext,
         varlist: TulispObject,
@@ -254,6 +255,8 @@ pub(crate) fn add(ctx: &mut TulispContext) {
 
         ret
     }
+    crate_add_func!(ctx, impl_let, "let");
+    crate_add_func!(ctx, impl_let, "let*");
 
     #[crate_fn_no_eval(add_func = "ctx")]
     fn progn(ctx: &mut TulispContext, rest: TulispObject) -> Result<TulispObject, Error> {
diff --git a/src/builtin/macros.rs b/src/builtin/macros.rs
index 33dc97f..b86dbc6 100644
--- a/src/builtin/macros.rs
+++ b/src/builtin/macros.rs
@@ -1,8 +1,5 @@
 use std::rc::Rc;
 
-use tulisp_proc_macros::{crate_add_macro, crate_fn_no_eval};
-
-use crate::cons::Cons;
 use crate::context::TulispContext;
 use crate::error::Error;
 use crate::TulispObject;
@@ -41,37 +38,6 @@ fn thread_last(_ctx: &mut TulispContext, vv: &TulispObject) -> Result<TulispObje
     }
 }
 
-#[crate_fn_no_eval]
-fn let_star(
-    ctx: &mut TulispContext,
-    varlist: TulispObject,
-    rest: TulispObject,
-) -> Result<TulispObject, Error> {
-    fn unwrap_varlist(
-        ctx: &mut TulispContext,
-        varlist: TulispObject,
-        body: TulispObject,
-    ) -> Result<TulispObject, Error> {
-        destruct_bind!((nextvar &rest rest) = varlist);
-
-        let mut ret = Cons::new(ctx.intern("let"), TulispObject::nil());
-        ret.push(list!(,nextvar)?)?;
-        if !rest.null() {
-            ret.push(unwrap_varlist(ctx, rest, body)?)?;
-        } else {
-            for ele in body.base_iter() {
-                ret.push(ele.clone())?;
-            }
-        }
-        Ok(TulispValue::List {
-            cons: ret,
-            ctxobj: Some(ctx.intern("let").get()?),
-        }
-        .into_ref())
-    }
-    unwrap_varlist(ctx, varlist, rest)
-}
-
 pub(crate) fn add(ctx: &mut TulispContext) {
     ctx.intern("->")
         .set_scope(TulispValue::Macro(Rc::new(thread_first)).into_ref())
@@ -85,6 +51,4 @@ pub(crate) fn add(ctx: &mut TulispContext) {
     ctx.intern("thread-last")
         .set_scope(TulispValue::Macro(Rc::new(thread_last)).into_ref())
         .unwrap();
-
-    crate_add_macro!(ctx, let_star, "let*");
 }
diff --git a/tests/tests.rs b/tests/tests.rs
index 11ec26c..24694dc 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -178,7 +178,7 @@ fn test_conditionals() -> Result<(), Error> {
 
     tulisp_assert! {
         program: "(macroexpand '(if-let (c) (+ c 10) 2))",
-        result_str: "'(let ((s (and t c))) (if s (+ c 10) 2))",
+        result_str: "'(let* ((s (and t c))) (if s (+ c 10) 2))",
     }
     tulisp_assert! {
         program: "(defun test (&optional c) (if-let (c) (+ c 10) 2)) (list (test) (test 2))",
@@ -203,27 +203,27 @@ fn test_conditionals() -> Result<(), Error> {
 
     tulisp_assert! {
         program: "(macroexpand '(when-let (c) (+ c 10)))",
-        result_str: "'(let ((s (and t c))) (if s (+ c 10) nil))",
+        result_str: "'(let* ((s (and t c))) (if s (+ c 10) nil))",
     }
     tulisp_assert! {
         program: "(macroexpand '(when-let (c) (+ c 10) 2))",
-        result_str: "'(let ((s (and t c))) (if s (progn (+ c 10) 2) nil))",
+        result_str: "'(let* ((s (and t c))) (if s (progn (+ c 10) 2) nil))",
     }
     tulisp_assert! {
         program: "(macroexpand '(when-let ((q c) d (w 10)) 2 (+ c d w)))",
         result_str: r#"'
-        (let ((q (and t c)))
-          (let ((d (and q d)))
-            (let ((w (and d 10)))
-              (if w
-                  (progn 2 (+ c d w))
-                 nil))))
+        (let* ((q (and t c))
+               (d (and q d))
+               (w (and d 10)))
+          (if w
+              (progn 2 (+ c d w))
+            nil))
         "#,
     }
 
     tulisp_assert! {
         program: "(macroexpand '(while-let (c) (+ c 10)))",
-        result_str: "'(while (let ((s (and t c))) (if s (progn (+ c 10) t) nil)))",
+        result_str: "'(while (let* ((s (and t c))) (if s (progn (+ c 10) t) nil)))",
     }
     tulisp_assert! {
         program: "(let ((ll '(1 2 3)) (vv 0)) (while-let (x (car ll))  (setq ll (cdr ll)) (setq vv (+ vv x))) vv)",
@@ -835,18 +835,18 @@ fn test_threading_macros() -> Result<(), Error> {
                                (print a))))
             "##,
         result_str: r##"
-        '(let ((s (and t a)))
-          (let ((s (and s b)))
-            (if s
-                (print a)
-              (let ((s (and t a)))
-                (if s
-                    (print a)
-                  (let ((s (and t b)))
-                    (if s
-                        (print b)
-                      nil)))))))
-            "##,
+        '(let* ((s (and t a))
+                (s (and s b)))
+           (if s
+               (print a)
+             (let* ((s (and t a)))
+               (if s
+                   (print a)
+                 (let* ((s (and t b)))
+                     (if s
+                         (print b)
+                       nil))))))
+        "##,
     }
 
     tulisp_assert! {