eval: add maptable

README.md

@@ -7,7 +7,6 @@
 ## TODOS
 
 - Destructuring assignment
-- `maptable`
 - `coerce`
 - `mac`
 - `````

eval/eval.go

@@ -481,6 +481,49 @@ func evalLen(l []*ast.AST) (*ast.AST, error) {
 	return &res, nil
 }
 
+func evalMapTable(l []*ast.AST, e ast.Env) (*ast.AST, error) {
+	err := checkArity(l, 2, "maptable")
+
+	if err != nil {
+		return nil, err
+	}
+
+	f, err := Eval(l[0], e)
+
+	if err != nil {
+		return nil, err
+	}
+
+	maybeLst, err := Eval(l[1], e)
+
+	if err != nil {
+		return nil, err
+	}
+
+	if maybeLst.Tag != ast.Table {
+		return nil, fmt.Errorf("Second argument to maptable must be table")
+	}
+
+	lst := maybeLst.Val.(map[*ast.AST]*ast.AST)
+
+	var res []*ast.AST
+
+	for k, v := range lst {
+		toEval := ast.AST{ast.List, []*ast.AST{f, k, v}}
+		evald, err := Eval(&toEval, e)
+
+		if err != nil {
+			return nil, err
+		}
+
+		res = append(res, evald)
+	}
+
+	reslst := ast.AST{ast.List, res}
+	quoted := ast.AST{ast.Quoted, &reslst}
+	return &quoted, nil
+}
+
 func evalSymbolList(l []*ast.AST, e ast.Env) (*ast.AST, error) {
 	sym := l[0].Val.(string)
 
@@ -519,6 +562,8 @@ func evalSymbolList(l []*ast.AST, e ast.Env) (*ast.AST, error) {
 		return evalLog(l, e, func(x float64, y float64) bool { return x < y })
 	case ">":
 		return evalLog(l, e, func(x float64, y float64) bool { return x > y })
+	case "maptable":
+		return evalMapTable(l, e)
 	}
 	res, err := e.Lookup(sym)