diff --git a/nasal_ast.h b/nasal_ast.h
index ddaeaf5..00c42d4 100644
--- a/nasal_ast.h
+++ b/nasal_ast.h
@@ -76,7 +76,7 @@ const char* ast_name[]=
     "func",
     "hash",
     "vec",
-    "hashmember",
+    "pair",
     "call",
     "callh",
     "callv",
diff --git a/nasal_builtin.h b/nasal_builtin.h
index 05a8061..72f4150 100644
--- a/nasal_builtin.h
+++ b/nasal_builtin.h
@@ -827,7 +827,6 @@ nas_ref builtin_readln(nas_ref* local,nasal_gc& gc)
     if(!fd.objchk(nas_obj::file))
         return builtin_err("readln","not a valid filehandle");
     nas_ref str=gc.alloc(vm_str);
-    auto& s=str.str();
     char c;
     while((c=fgetc((FILE*)fd.obj().ptr))!=EOF)
     {
@@ -835,9 +834,9 @@ nas_ref builtin_readln(nas_ref* local,nasal_gc& gc)
             continue;
         if(c=='\n')
             return str;
-        s+=c;
+        str.str()+=c;
     }
-    if(s.length())
+    if(str.str().length())
         return str;
     return nil;
 }
@@ -998,8 +997,7 @@ nas_ref builtin_waitpid(nas_ref* local,nasal_gc& gc)
     if(pid.type!=vm_num || nohang.type!=vm_num)
         return builtin_err("waitpid","pid and nohang must be number");
 #ifndef _WIN32
-    i32 ret_pid;
-    i32 status;
+    i32 ret_pid,status;
     ret_pid=waitpid(pid.num(),&status,nohang.num()==0?0:WNOHANG);
     nas_ref vec=gc.alloc(vm_vec);
     vec.vec().elems.push_back({vm_num,(f64)ret_pid});
@@ -1075,14 +1073,10 @@ nas_ref builtin_chdir(nas_ref* local,nasal_gc& gc)
 }
 nas_ref builtin_environ(nas_ref* local,nasal_gc& gc)
 {
-    char** env=environ;
     nas_ref res=gc.temp=gc.alloc(vm_vec);
     auto& vec=res.vec().elems;
-    while(*env)
-    {
+    for(char** env=environ;*env;++env)
         vec.push_back(gc.newstr(*env));
-        ++env;
-    }
     gc.temp=nil;
     return res;
 }
@@ -1167,12 +1161,12 @@ nas_ref builtin_dlclose(nas_ref* local,nasal_gc& gc)
 }
 nas_ref builtin_dlcall(nas_ref* local,nasal_gc& gc)
 {
-    nas_ref funcptr=local[1];
+    nas_ref fp=local[1];
     nas_ref args=local[2];
-    if(!funcptr.objchk(nas_obj::faddr))
+    if(!fp.objchk(nas_obj::faddr))
         return builtin_err("dlcall","\"funcptr\" is not a valid function pointer");
     typedef nas_ref (*externs)(std::vector<nas_ref>&,nasal_gc&);
-    externs func=(externs)funcptr.obj().ptr;
+    externs func=(externs)fp.obj().ptr;
     return func(args.vec().elems,gc);
 }
 nas_ref builtin_platform(nas_ref* local,nasal_gc& gc)
@@ -1353,9 +1347,7 @@ nas_ref builtin_costatus(nas_ref* local,nasal_gc& gc)
 }
 nas_ref builtin_corun(nas_ref* local,nasal_gc& gc)
 {
-    if(gc.cort)
-        return one;
-    return zero;
+    return gc.cort?one:zero;
 }
 nas_ref builtin_millisec(nas_ref* local,nasal_gc& gc)
 {
diff --git a/nasal_codegen.h b/nasal_codegen.h
index c4fe46f..4f146b6 100644
--- a/nasal_codegen.h
+++ b/nasal_codegen.h
@@ -82,81 +82,25 @@ enum op_code:u8
 
 const char* code_table[]=
 {
-    "exit  ",
-    "intg  ",
-    "intl  ",
-    "loadg ",
-    "loadl ",
-    "loadu ",
-    "pnum  ",
-    "pnil  ",
-    "pstr  ",
-    "newv  ",
-    "newh  ",
-    "newf  ",
-    "happ  ",
-    "para  ",
-    "def   ",
-    "dyn   ",
-    "not   ",
-    "usub  ",
-    "add   ",
-    "sub   ",
-    "mult  ",
-    "div   ",
-    "lnk   ",
-    "addc  ",
-    "subc  ",
-    "multc ",
-    "divc  ",
-    "lnkc  ",
-    "addeq ",
-    "subeq ",
-    "muleq ",
-    "diveq ",
-    "lnkeq ",
-    "addeqc",
-    "subeqc",
-    "muleqc",
-    "diveqc",
-    "lnkeqc",
-    "meq   ",
-    "eq    ",
-    "neq   ",
-    "less  ",
-    "leq   ",
-    "grt   ",
-    "geq   ",
-    "lessc ",
-    "leqc  ",
-    "grtc  ",
-    "geqc  ",
-    "pop   ",
-    "jmp   ",
-    "jt    ",
-    "jf    ",
-    "cnt   ",
-    "findx ",
-    "feach ",
-    "callg ",
-    "calll ",
-    "upval ",
-    "callv ",
-    "callvi",
-    "callh ",
-    "callfv",
-    "callfh",
-    "callb ",
-    "slcbeg",
-    "slcend",
-    "slc   ",
-    "slc2  ",
-    "mcallg",
-    "mcalll",
-    "mupval",
-    "mcallv",
-    "mcallh",
-    "ret   "
+    "exit  ","intg  ","intl  ","loadg ",
+    "loadl ","loadu ","pnum  ","pnil  ",
+    "pstr  ","newv  ","newh  ","newf  ",
+    "happ  ","para  ","def   ","dyn   ",
+    "not   ","usub  ","add   ","sub   ",
+    "mult  ","div   ","lnk   ","addc  ",
+    "subc  ","multc ","divc  ","lnkc  ",
+    "addeq ","subeq ","muleq ","diveq ",
+    "lnkeq ","addeqc","subeqc","muleqc",
+    "diveqc","lnkeqc","meq   ","eq    ",
+    "neq   ","less  ","leq   ","grt   ",
+    "geq   ","lessc ","leqc  ","grtc  ",
+    "geqc  ","pop   ","jmp   ","jt    ",
+    "jf    ","cnt   ","findx ","feach ",
+    "callg ","calll ","upval ","callv ",
+    "callvi","callh ","callfv","callfh",
+    "callb ","slcbeg","slcend","slc   ",
+    "slc2  ","mcallg","mcalll","mupval",
+    "mcallv","mcallh","ret   "
 };
 
 struct opcode