rework eval loop to unwrap lists when function calls return

ast/eval.go

@@ -19,15 +19,17 @@ package ast
 
 import "git.callpipe.com/aidan/shs/log"
 
-func (t *Token) Eval(funcs FuncTable, vars VarTable) *Token {
+func (t *Token) Eval(funcs FuncTable, vars VarTable) (*Token, bool) {
     if t == nil {
-        return nil
+        return nil, false
     }
 
     eligibleForSystemCall := true
 
     var reduce func(*Token) *Token
     reduce = func(t_ *Token) *Token {
+        var unwrap bool
+
         if t_.Next != nil {
             t_.Next = reduce(t_.Next)
         }
@@ -36,7 +38,12 @@ func (t *Token) Eval(funcs FuncTable, vars VarTable) *Token {
         case SYMBOL:
             maybeToken := GetVar(t_.Inner.(string), vars)
             if maybeToken != nil {
-                tok := maybeToken.Eval(funcs, vars)
+                tok, _ := maybeToken.Eval(funcs, vars)
+                // Should already be unwrapped
+                //if unwrap {
+                //    tok = tok.Inner.(*Token)
+                //}
+
                 if tok.Tag == LIST {
                     eligibleForSystemCall = false
                 }
@@ -47,13 +54,33 @@ func (t *Token) Eval(funcs FuncTable, vars VarTable) *Token {
 
         case LIST:
             eligibleForSystemCall = false
-            t_.Inner = t_.Inner.(*Token).Eval(funcs, vars)
+            t_.Inner, unwrap = t_.Inner.(*Token).Eval(funcs, vars)
+            if unwrap {
+                next := t_.Next
+                t_ = t_.Inner.(*Token)
+                if t_ == nil {
+                    log.Log(log.DEBUG, "nil Inner on list unwrap", "eval")
+                    return nil
+                }
+
+                i := &t_
+                for (*i).Next != nil {
+                    i = &((*i).Next)
+                }
+
+                (*i).Next = next
+            }
         }
 
         return t_
     }
 
     ret := reduce(t)
+    if ret == nil {
+        log.Log(log.INFO, "reduce returned nil", "eval")
+        return nil, false
+    }
+
     if ret.Tag == SYMBOL {
         f := GetFunction(ret.Inner.(string), funcs)
         if f == nil {
@@ -61,15 +88,15 @@ func (t *Token) Eval(funcs FuncTable, vars VarTable) *Token {
                 log.Log(log.DEBUG,
                     "could not find definition for symbol " + ret.Inner.(string),
                     "eval")
-                return nil
+                return nil, false
             }
 
             // TODO: hook into stdlib exec
-            return nil // TODO: Thats gotta change
+            return nil, false // TODO: Thats gotta change
         }
 
-        return (*f).CallFunction(ret.Next, vars, funcs)
+        return (*f).CallFunction(ret.Next, vars, funcs), true
     }
 
-    return ret
+    return ret, false
 }