refine macro code for cond and let[]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "calcit_runner"
-version = "0.5.0-a8"
+version = "0.5.0-a9"
 authors = ["jiyinyiyong <jiyinyiyong@gmail.com>"]
 edition = "2018"
 license = "MIT"

calcit/snapshots/test-macro.cirru

@@ -341,6 +341,32 @@
                 quote $ let{} (a b) ({,} :a 3 :b 4)
                   + a b
 
+              &reset-gensym-index!
+
+              assert=
+                macroexpand-all $ quote
+                  let[] (a b) ([] 1 2)
+                    + a b
+                quasiquote $ ~&let (v__1 (~[] 1 2))
+                  ~&let (a (~&list:nth v__1 0))
+                    ~&let (b (~&list:nth v__1 1))
+                      + a b
+
+              assert=
+                macroexpand-all $ quote
+                  let[] (a b) xs
+                    + a b
+                quasiquote $ ~&let (a (~&list:nth xs 0))
+                  ~&let (b (~&list:nth xs 1))
+                    + a b
+
+              assert=
+                macroexpand-all $ quote
+                  cond
+                    (= a 1) |one
+                    true |other
+                quasiquote $ ~if (= a 1) |one |other
+
             assert=
               [] 3 4 5 6
               let-sugar

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@calcit/procs",
-  "version": "0.5.0-a8",
+  "version": "0.5.0-a9",
   "main": "./lib/calcit.procs.js",
   "devDependencies": {
     "@types/node": "^16.10.5",

src/cirru/calcit-core.cirru

@@ -338,13 +338,16 @@
               expr $ &list:nth pair 0
               &let
                 branch $ &list:nth pair 1
-                quasiquote
-                  if ~expr ~branch
-                    ~ $ if (&list:empty? else) nil
-                      quasiquote
-                        cond
-                          ~ $ &list:nth else 0
-                          ~@ $ &list:rest else
+                if
+                  if (empty? else) (= true expr) false
+                  , branch
+                  quasiquote
+                    if ~expr ~branch
+                      ~ $ if (&list:empty? else) nil
+                        quasiquote
+                          cond
+                            ~ $ &list:nth else 0
+                            ~@ $ &list:rest else
 
         |key-match $ quote
           defmacro key-match (value & body)
@@ -1155,7 +1158,8 @@
                 every? vars symbol?
                 , false
             let
-                v $ gensym |v
+                variable? $ symbol? data
+                v $ if variable? data $ gensym |v
                 defs $ apply-args
                   [] ([]) vars 0
                   defn let[]% (acc xs idx)
@@ -1172,12 +1176,18 @@
                             append acc $ [] (&list:first xs) (quasiquote (&list:nth ~v ~idx))
                             rest xs
                             inc idx
-              quasiquote
-                &let
-                  ~v ~data
+
+              if variable?
+                quasiquote
                   let
                     ~ defs
                     ~@ body
+                quasiquote
+                  &let
+                    ~v ~data
+                    let
+                      ~ defs
+                      ~@ body
 
         |defrecord $ quote
           defmacro defrecord (name & xs)

ts-src/calcit.procs.ts

@@ -1,5 +1,5 @@
 // CALCIT VERSION
-export const calcit_version = "0.5.0-a8";
+export const calcit_version = "0.5.0-a9";
 
 import { overwriteComparator, initTernaryTreeMap } from "@calcit/ternary-tree";
 import { parse, ICirruNode } from "@cirru/parser.ts";