From 9d106d427855eb9ad0af106a29af7d56fd98b5cf Mon Sep 17 00:00:00 2001
From: Sameer Rahmani <lxsameer@gnu.org>
Date: Wed, 30 Dec 2020 17:50:00 +0000
Subject: [PATCH] Record the caller details in the stack frame

---
 bootstrap/examples/hello-world.srn |  2 +-
 bootstrap/go.mod                   |  1 +
 bootstrap/go.sum                   |  2 +
 bootstrap/pkg/ast/ast.go           | 88 ++++++++++++++++++++++++++----
 bootstrap/pkg/core/block.go        |  2 +-
 bootstrap/pkg/core/builtins.go     |  6 +-
 bootstrap/pkg/core/call_stack.go   | 79 +++++++++++++++++++++------
 bootstrap/pkg/core/core.go         | 28 +++++++---
 bootstrap/pkg/core/errors.go       | 29 ++++------
 bootstrap/pkg/core/eval.go         | 60 +++++++++++---------
 bootstrap/pkg/core/function.go     | 28 ++++++++--
 bootstrap/pkg/core/keyword.go      |  2 +-
 bootstrap/pkg/core/list.go         | 21 +++++--
 bootstrap/pkg/core/namespace.go    | 17 +++---
 bootstrap/pkg/core/nothing.go      |  2 +-
 bootstrap/pkg/core/parser.go       | 71 ++++++++++++++++++------
 bootstrap/pkg/core/printer.go      | 34 +++++++++++-
 bootstrap/pkg/core/quasiquote.go   | 11 +++-
 bootstrap/pkg/core/reader.go       |  4 +-
 bootstrap/pkg/core/runtime.go      |  9 +--
 bootstrap/pkg/core/sforms.go       | 26 ++++-----
 bootstrap/pkg/core/types.go        | 28 ++++++++--
 dev.org                            |  1 +
 23 files changed, 399 insertions(+), 152 deletions(-)

diff --git a/bootstrap/examples/hello-world.srn b/bootstrap/examples/hello-world.srn
index 460fdd9..f206f87 100644
--- a/bootstrap/examples/hello-world.srn
+++ b/bootstrap/examples/hello-world.srn
@@ -9,7 +9,7 @@
   (name args &body)
   (list 'def name (cons 'fn (cons args body))))
 
-(defn pp (x)
+(defn pp (x y)
   (println x))
 
 (def main
diff --git a/bootstrap/go.mod b/bootstrap/go.mod
index 24fb38b..8d2dafb 100644
--- a/bootstrap/go.mod
+++ b/bootstrap/go.mod
@@ -4,6 +4,7 @@ go 1.15
 
 require (
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
+	github.com/gookit/color v1.3.5
 	github.com/rjeczalik/pkgconfig v0.0.0-20190903131546-94d388dab445
 	github.com/spf13/cobra v1.1.1
 	github.com/spf13/viper v1.7.1
diff --git a/bootstrap/go.sum b/bootstrap/go.sum
index 04c2ecb..0a71ec0 100644
--- a/bootstrap/go.sum
+++ b/bootstrap/go.sum
@@ -68,6 +68,8 @@ github.com/google/pprof v0.0.0-20190515194954-54271f7e092f/go.mod h1:zfwlbNMJ+OI
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
+github.com/gookit/color v1.3.5 h1:1nszcmDVrfti1Su5fhtuS5YBs/Xs6v8UIi0bJ/2oDHY=
+github.com/gookit/color v1.3.5/go.mod h1:GqqLKF1le3EfrbHbYsYa5WdLqfc/PHMdMRbt6tMnqIc=
 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/grpc-ecosystem/go-grpc-middleware v1.0.0/go.mod h1:FiyG127CGDf3tlThmgyCl78X/SZQqEOJBCDaAfeWzPs=
diff --git a/bootstrap/pkg/ast/ast.go b/bootstrap/pkg/ast/ast.go
index 298ce47..8bd421f 100644
--- a/bootstrap/pkg/ast/ast.go
+++ b/bootstrap/pkg/ast/ast.go
@@ -20,6 +20,11 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 // Serene's AST.
 package ast
 
+import (
+	"sort"
+	"strings"
+)
+
 type NodeType int
 
 const (
@@ -40,13 +45,42 @@ const (
 
 )
 
+type Source struct {
+	Buffer *[]string
+	// It can be the path to the source file or something like "*in*"
+	// for standard in
+	Path      string
+	LineIndex *[]int
+}
+
+func (s *Source) GetLine(linenum int) string {
+	lines := strings.Split(strings.Join(*s.Buffer, ""), "\n")
+	return lines[linenum-1]
+}
+
+func (s *Source) LineNumberFor(pos int) int {
+	if pos < 0 {
+		return -1
+	}
+
+	return sort.Search(len(*s.LineIndex), func(i int) bool {
+		if i == 0 {
+			return pos < (*s.LineIndex)[i]
+		} else {
+			return (*s.LineIndex)[i-1] < pos && pos < (*s.LineIndex)[i]
+		}
+	})
+}
+
 type Location struct {
 	start         int
 	end           int
-	source        *[]string
+	source        Source
 	knownLocation bool
 }
 
+var UnknownLocation *Location = &Location{knownLocation: false}
+
 func (l *Location) GetStart() int {
 	return l.start
 }
@@ -55,8 +89,42 @@ func (l *Location) GetEnd() int {
 	return l.end
 }
 
-func (l *Location) GetSource() *[]string {
-	return l.source
+func (l *Location) GetSource() *Source {
+	return &l.source
+}
+
+func (l *Location) IncStart(x int) {
+	if x+l.start < len(*l.source.Buffer) {
+		l.start += x
+	} else {
+		l.start = len(*l.source.Buffer) - 1
+	}
+}
+
+func (l *Location) DecStart(x int) {
+	if l.start-x >= 0 {
+		l.start -= x
+	} else {
+		l.start = 0
+	}
+
+}
+
+func (l *Location) IncEnd(x int) {
+	if x+l.end < len(*l.source.Buffer) {
+		l.end += x
+	} else {
+		l.end = len(*l.source.Buffer) - 1
+	}
+
+}
+
+func (l *Location) DecEnd(x int) {
+	if l.end-x >= 0 {
+		l.end -= x
+	} else {
+		l.end = 0
+	}
 }
 
 func (l *Location) IsKnownLocaiton() bool {
@@ -64,12 +132,12 @@ func (l *Location) IsKnownLocaiton() bool {
 }
 
 type ILocatable interface {
-	GetLocation() Location
+	GetLocation() *Location
 }
 
-func MakeLocation(input *[]string, start int, end int) Location {
-	return Location{
-		source:        input,
+func MakeLocation(input *Source, start int, end int) *Location {
+	return &Location{
+		source:        *input,
 		start:         start,
 		end:           end,
 		knownLocation: true,
@@ -80,8 +148,6 @@ type ITypable interface {
 	GetType() NodeType
 }
 
-func MakeUnknownLocation() Location {
-	return Location{
-		knownLocation: false,
-	}
+func MakeUnknownLocation() *Location {
+	return UnknownLocation
 }
diff --git a/bootstrap/pkg/core/block.go b/bootstrap/pkg/core/block.go
index 308f9a3..8b7fef1 100644
--- a/bootstrap/pkg/core/block.go
+++ b/bootstrap/pkg/core/block.go
@@ -51,7 +51,7 @@ func (b *Block) ToDebugStr() string {
 	return fmt.Sprintf("%#v", b)
 }
 
-func (b *Block) GetLocation() ast.Location {
+func (b *Block) GetLocation() *ast.Location {
 	if len(b.body) > 0 {
 		return b.body[0].GetLocation()
 	}
diff --git a/bootstrap/pkg/core/builtins.go b/bootstrap/pkg/core/builtins.go
index 08cb606..f96a87d 100644
--- a/bootstrap/pkg/core/builtins.go
+++ b/bootstrap/pkg/core/builtins.go
@@ -53,9 +53,9 @@ func PrintlnNativeFn(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IErr
 func RequireNativeFn(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IError) {
 	switch args.Count() {
 	case 0:
-		return nil, MakeErrorFor(rt, args, "'require' function is missing")
+		return nil, MakeError(rt, args, "'require' function is missing")
 	case 1:
-		return nil, MakeErrorFor(rt, args.First(), "'require' function needs at least one argument")
+		return nil, MakeError(rt, args.First(), "'require' function needs at least one argument")
 	default:
 	}
 
@@ -74,7 +74,7 @@ func RequireNativeFn(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IErr
 
 func HashNativeFn(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IError) {
 	if args.Count() != 2 {
-		return nil, MakeErrorFor(rt, args.First(), "'hash' function needs exactly one argument")
+		return nil, MakeError(rt, args.First(), "'hash' function needs exactly one argument")
 	}
 
 	expr := args.Rest().First()
diff --git a/bootstrap/pkg/core/call_stack.go b/bootstrap/pkg/core/call_stack.go
index 51b5883..d8023c7 100644
--- a/bootstrap/pkg/core/call_stack.go
+++ b/bootstrap/pkg/core/call_stack.go
@@ -33,38 +33,51 @@ package core
 //   compare the stack items by their address, identity and location.
 // * Add support for iteration on the stack.
 
-import "fmt"
+import (
+	"fmt"
+)
 
 type ICallStack interface {
 	// Push the given callable `f` to the stack
 	Push(f IFn) IError
-	Pop() FnCall
+	Pop() *Frame
+	Peek() *Frame
 	Count() uint
 }
 
-type FnCall struct {
-	Fn IFn
+type Frame struct {
 	// Number of recursive calls to this function
-	count uint
+	Count  uint
+	Fn     IFn
+	Caller IExpr
 }
 
+type TraceBack = []Frame
+
 type CallStackItem struct {
 	prev *CallStackItem
-	data FnCall
+	data Frame
 }
 
 type CallStack struct {
+	debug bool
 	head  *CallStackItem
 	count uint
-	debug bool
 }
 
 func (c *CallStack) Count() uint {
 	return c.count
 }
 
-func (c *CallStack) Push(f IFn) IError {
+func (c *CallStack) GetCurrentFn() IFn {
+	if c.head == nil {
+		return nil
+	}
 
+	return c.head.data.Fn
+}
+
+func (c *CallStack) Push(caller IExpr, f IFn) IError {
 	if c.debug {
 		fmt.Println("[Stack] -->", f)
 	}
@@ -73,12 +86,17 @@ func (c *CallStack) Push(f IFn) IError {
 		return MakePlainError("Can't push 'nil' pointer to the call stack.")
 	}
 
+	if caller == nil {
+		return MakePlainError("Can't push 'nil' pointer to the call stack for the caller.")
+	}
+
 	// Empty Stack
 	if c.head == nil {
 		c.head = &CallStackItem{
-			data: FnCall{
-				Fn:    f,
-				count: 0,
+			data: Frame{
+				Fn:     f,
+				Caller: caller,
+				Count:  0,
 			},
 		}
 		c.count++
@@ -87,15 +105,16 @@ func (c *CallStack) Push(f IFn) IError {
 	nodeData := &c.head.data
 
 	// If the same function was on top of the stack
-	if nodeData.Fn == f {
+	if nodeData.Fn == f && caller == nodeData.Caller {
 		// TODO: expand the check here to support address and location as well
-		nodeData.count++
+		nodeData.Count++
 	} else {
 		c.head = &CallStackItem{
 			prev: c.head,
-			data: FnCall{
-				Fn:    f,
-				count: 0,
+			data: Frame{
+				Fn:     f,
+				Caller: caller,
+				Count:  0,
 			},
 		}
 		c.count++
@@ -103,7 +122,7 @@ func (c *CallStack) Push(f IFn) IError {
 	return nil
 }
 
-func (c *CallStack) Pop() *FnCall {
+func (c *CallStack) Pop() *Frame {
 	if c.head == nil {
 		if c.debug {
 			fmt.Println("[Stack] <-- nil")
@@ -120,6 +139,32 @@ func (c *CallStack) Pop() *FnCall {
 	return &result.data
 }
 
+func (c *CallStack) Peek() *Frame {
+	if c.head == nil {
+		if c.debug {
+			fmt.Println("[Stack] <-- nil")
+		}
+		return nil
+	}
+
+	result := c.head
+	return &result.data
+}
+
+func (c *CallStack) ToTraceBack() *TraceBack {
+	var tr TraceBack
+	item := c.head
+	for {
+		if item == nil {
+			break
+		}
+		tr = append(tr, item.data)
+		item = item.prev
+	}
+
+	return &tr
+}
+
 func MakeCallStack(debugMode bool) CallStack {
 	return CallStack{
 		count: 0,
diff --git a/bootstrap/pkg/core/core.go b/bootstrap/pkg/core/core.go
index e5aa750..ac40a56 100644
--- a/bootstrap/pkg/core/core.go
+++ b/bootstrap/pkg/core/core.go
@@ -23,13 +23,14 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/chzyer/readline"
 	"serene-lang.org/bootstrap/pkg/ast"
 )
 
 func rep(rt *Runtime, line string) {
-	ast, err := ReadString(line)
+	ast, err := ReadString("*REPL*", line)
 
 	if err != nil {
 		PrintError(rt, err)
@@ -120,7 +121,17 @@ func Run(flags map[string]bool, args []string) {
 	}
 
 	ns := args[0]
-	loadedNS, err := requireNS(rt, ns)
+	nsAsBuffer := strings.Split(ns, "")
+	source := &ast.Source{Buffer: &nsAsBuffer, Path: "*input-argument*"}
+	node := MakeNode(source, 0, len(ns))
+	nsSym, err := MakeSymbol(node, ns)
+
+	if err != nil {
+		PrintError(rt, err)
+		os.Exit(1)
+	}
+
+	loadedNS, err := requireNS(rt, nsSym)
 
 	if err != nil {
 		PrintError(rt, err)
@@ -133,6 +144,7 @@ func Run(flags map[string]bool, args []string) {
 	if !inserted {
 		err := MakeError(
 			rt,
+			loadedNS,
 			fmt.Sprintf(
 				"the namespace '%s' didn't get inserted in the runtime.",
 				loadedNS.GetName()),
@@ -163,24 +175,22 @@ func Run(flags map[string]bool, args []string) {
 	mainFn := mainBinding.Value.(*Function)
 
 	var fnArgs []IExpr
+	var argNode Node
 
 	if len(args) > 1 {
 		for _, arg := range args[1:] {
 			node := MakeNodeFromExpr(mainFn)
 			fnArgs = append(fnArgs, MakeString(node, arg))
 		}
+		argNode = MakeNodeFromExprs(fnArgs)
+	} else {
+		argNode = node
 	}
 
-	//rt.Stack.Push(mainFn)
-	_, err = mainFn.Apply(rt, loadedNS.GetRootScope(), mainFn.Node, MakeList(fnArgs))
+	_, err = mainFn.Apply(rt, loadedNS.GetRootScope(), mainFn.Node, MakeList(argNode, fnArgs))
 
 	if err != nil {
 		PrintError(rt, err)
 		os.Exit(1)
 	}
-
-	// rt.Stack.Pop()
-	// if rt.Stack.Count() != 0 {
-	// 	panic("Call stack is not empty.")
-	// }
 }
diff --git a/bootstrap/pkg/core/errors.go b/bootstrap/pkg/core/errors.go
index 7e3d4aa..35f8a83 100644
--- a/bootstrap/pkg/core/errors.go
+++ b/bootstrap/pkg/core/errors.go
@@ -49,6 +49,7 @@ type IError interface {
 	IRepresentable
 	IDebuggable
 
+	GetStackTrace() *TraceBack
 	// To wrap Golan rrrrors
 	WithError(err error) IError
 
@@ -62,6 +63,7 @@ type Error struct {
 	Node
 	WrappedErr error
 	msg        string
+	trace      *TraceBack
 }
 
 func (e *Error) String() string {
@@ -89,32 +91,25 @@ func (e *Error) Error() string {
 	return e.msg
 }
 
+func (e *Error) GetStackTrace() *TraceBack {
+	return e.trace
+}
+
 func MakePlainError(msg string) IError {
 	return &Error{
 		msg: msg,
 	}
 }
 
-// MakeError creates an Error without any location.
-func MakeError(rt *Runtime, msg string) IError {
-	return MakePlainError(msg)
-}
-
-// MakeErrorFor creates an Error which points to the given IExpr `e` as
+// MakeError creates an Error which points to the given IExpr `e` as
 // the root of the error.
-func MakeErrorFor(rt *Runtime, e IExpr, msg string) IError {
-	loc := e.GetLocation()
+func MakeError(rt *Runtime, e IExpr, msg string) IError {
+	trace := append(*rt.Stack.ToTraceBack(), Frame{0, rt.Stack.GetCurrentFn(), e})
 
 	return &Error{
-		Node: MakeNodeFromLocation(loc),
-		msg:  msg,
-	}
-}
-
-//MakeRuntimeErrorf is a helper function which works like `fmt.Errorf`
-func MakeRuntimeErrorf(rt *Runtime, msg string, a ...interface{}) IError {
-	return &Error{
-		msg: fmt.Sprintf(msg, a...),
+		Node:  MakeNodeFromExpr(e),
+		msg:   msg,
+		trace: &trace,
 	}
 }
 
diff --git a/bootstrap/pkg/core/eval.go b/bootstrap/pkg/core/eval.go
index a7dd0e4..b73a950 100644
--- a/bootstrap/pkg/core/eval.go
+++ b/bootstrap/pkg/core/eval.go
@@ -84,7 +84,7 @@ func evalForm(rt *Runtime, scope IScope, form IExpr) (IExpr, IError) {
 			if sym.IsNSQualified() {
 				// Whether a namespace with the given alias loaded or not
 				if !rt.CurrentNS().hasExternal(sym.GetNSPart()) {
-					return nil, MakeErrorFor(rt, sym,
+					return nil, MakeError(rt, sym,
 						fmt.Sprintf("Namespace '%s' is no loaded", sym.GetNSPart()),
 					)
 				}
@@ -97,11 +97,14 @@ func evalForm(rt *Runtime, scope IScope, form IExpr) (IExpr, IError) {
 			}
 
 			if expr == nil {
-				return nil, MakeRuntimeErrorf(
+				return nil, MakeError(
 					rt,
-					"can't resolve symbol '%s' in ns '%s'",
-					symbolName,
-					nsName,
+					sym,
+					fmt.Sprintf(
+						"can't resolve symbol '%s' in ns '%s'",
+						symbolName,
+						nsName,
+					),
 				)
 			}
 
@@ -126,11 +129,12 @@ func evalForm(rt *Runtime, scope IScope, form IExpr) (IExpr, IError) {
 				break
 			}
 		}
-		return MakeList(result), nil
+
+		return MakeList(MakeNodeFromExpr(lst), result), nil
 	}
 
 	// Default case
-	return nil, MakeError(rt, fmt.Sprintf("support for '%d' is not implemented", form.GetType()))
+	return nil, MakeError(rt, form, fmt.Sprintf("support for '%d' is not implemented", form.GetType()))
 }
 
 // EvalForms evaluates the given expr `expressions` (it can be a list, block, symbol or anything else)
@@ -185,7 +189,6 @@ tco:
 
 	body:
 		for i := 0; i < len(exprs); i++ {
-			//for i, forms := range exprs {
 			forms := exprs[i]
 			executionScope := forms.GetExecutionScope()
 			scope := scope
@@ -275,7 +278,7 @@ tco:
 			case "quote":
 				// Including the `quote` itself
 				if list.Count() != 2 {
-					return nil, MakeErrorFor(rt, list, "'quote' quote only accepts one argument.")
+					return nil, MakeError(rt, list, "'quote' quote only accepts one argument.")
 				}
 				ret = list.Rest().First()
 				err = nil
@@ -310,12 +313,18 @@ tco:
 				result := []IExpr{}
 				for _, lst := range lists {
 					if lst.GetType() != ast.List {
-						return nil, MakeErrorFor(rt, lst, fmt.Sprintf("don't know how to concat '%s'", lst.String()))
+						return nil, MakeError(rt, lst, fmt.Sprintf("don't know how to concat '%s'", lst.String()))
 					}
 
 					result = append(result, lst.(*List).ToSlice()...)
 				}
-				ret, err = MakeList(result), nil
+
+				node := MakeNodeFromExpr(list)
+				if len(result) > 0 {
+					node = MakeNodeFromExprs(result)
+				}
+
+				ret, err = MakeList(node, result), nil
 				continue body // no rewrite
 
 			// TODO: Implement `list` in serene itself when we have destructuring available
@@ -324,7 +333,7 @@ tco:
 			// given in the second argument.
 			case "cons":
 				if list.Count() != 3 {
-					return nil, MakeErrorFor(rt, list, "'cons' needs exactly 3 arguments")
+					return nil, MakeError(rt, list, "'cons' needs exactly 3 arguments")
 				}
 
 				evaledForms, err := evalForm(rt, scope, list.Rest().(*List))
@@ -335,7 +344,7 @@ tco:
 				coll, ok := evaledForms.(*List).Rest().First().(IColl)
 
 				if !ok {
-					return nil, MakeErrorFor(rt, list, "second arg of 'cons' has to be a collection")
+					return nil, MakeError(rt, list, "second arg of 'cons' has to be a collection")
 				}
 
 				ret, err = coll.Cons(evaledForms.(*List).First()), nil
@@ -366,7 +375,7 @@ tco:
 			//   as a macro and returns the expanded forms.
 			case "macroexpand":
 				if list.Count() != 2 {
-					return nil, MakeErrorFor(rt, list, "'macroexpand' needs exactly one argument.")
+					return nil, MakeError(rt, list, "'macroexpand' needs exactly one argument.")
 				}
 				evaledForm, e := evalForm(rt, scope, list.Rest().(*List))
 
@@ -381,7 +390,7 @@ tco:
 			// * It needs at least a collection of arguments
 			// * Defines an anonymous function.
 			case "fn":
-				ret, err = Fn(rt, scope, list.Rest().(*List))
+				ret, err = Fn(rt, scope, list)
 				continue body // no rewrite
 
 			// `if` evaluation rules:
@@ -392,7 +401,7 @@ tco:
 			case "if":
 				args := list.Rest().(*List)
 				if args.Count() != 3 {
-					return nil, MakeError(rt, "'if' needs exactly 3 aruments")
+					return nil, MakeError(rt, args, "'if' needs exactly 3 aruments")
 				}
 
 				pred, err := EvalForms(rt, scope, args.First())
@@ -436,7 +445,7 @@ tco:
 			//   the result.
 			case "eval":
 				if list.Count() != 2 {
-					return nil, MakeErrorFor(rt, list, "'eval' needs exactly 1 arguments")
+					return nil, MakeError(rt, list, "'eval' needs exactly 1 arguments")
 				}
 				form, err := evalForm(rt, scope, list.Rest().(*List))
 				if err != nil {
@@ -457,7 +466,7 @@ tco:
 			//   which is the result of the last expre in `BODY`
 			case "let":
 				if list.Count() < 2 {
-					return nil, MakeError(rt, "'let' needs at list 1 aruments")
+					return nil, MakeError(rt, list, "'let' needs at list 1 aruments")
 				}
 
 				letScope := MakeScope(scope.(*Scope))
@@ -470,7 +479,7 @@ tco:
 				body := list.Rest().Rest().(*List).ToSlice()
 
 				if bindings.Count()%2 != 0 {
-					return nil, MakeError(rt, "'let' bindings has to have even number of forms.")
+					return nil, MakeError(rt, list.Rest().First(), "'let' bindings has to have even number of forms.")
 				}
 
 				for {
@@ -485,7 +494,7 @@ tco:
 					// TODO: We need to destruct the bindings here and remove this check
 					//       for the symbol type
 					if name.GetType() != ast.Symbol {
-						err := MakeErrorFor(rt, name, "'let' doesn't support desbbtructuring yet, use a symbol.")
+						err := MakeError(rt, name, "'let' doesn't support desbbtructuring yet, use a symbol.")
 						return nil, err
 					}
 
@@ -546,7 +555,7 @@ tco:
 						break body //return
 					}
 
-					rt.Stack.Push(fn)
+					rt.Stack.Push(list, fn)
 					body := append(
 						fn.GetBody().ToSlice(),
 						// Add the PopStack instruction to clean up the stack after
@@ -561,7 +570,8 @@ tco:
 				// by the `NativeFunction` struct
 				case ast.NativeFn:
 					fn := f.(*NativeFunction)
-					rt.Stack.Push(fn)
+
+					rt.Stack.Push(list, fn)
 					ret, err = fn.Apply(
 						rt,
 						scope,
@@ -572,7 +582,7 @@ tco:
 					continue body // no rewrite
 
 				default:
-					err = MakeError(rt, "don't know how to execute anything beside function")
+					err = MakeError(rt, f, "don't know how to execute anything beside function")
 					ret = nil
 					break tco
 				}
@@ -613,7 +623,7 @@ func EvalNSBody(rt *Runtime, ns *Namespace) (*Namespace, IError) {
 	exprs := body.ToSlice()
 
 	if len(exprs) == 0 {
-		return nil, MakeError(rt, fmt.Sprintf("the 'ns' form is missing from '%s'", ns.GetName()))
+		return nil, MakeError(rt, ns, fmt.Sprintf("the 'ns' form is missing from '%s'", ns.GetName()))
 	}
 
 	if exprs[0].GetType() == ast.List {
@@ -627,5 +637,5 @@ func EvalNSBody(rt *Runtime, ns *Namespace) (*Namespace, IError) {
 		}
 	}
 
-	return nil, MakeError(rt, fmt.Sprintf("the 'ns' form is missing from '%s'", ns.GetName()))
+	return nil, MakeError(rt, ns, fmt.Sprintf("the 'ns' form is missing from '%s'", ns.GetName()))
 }
diff --git a/bootstrap/pkg/core/function.go b/bootstrap/pkg/core/function.go
index b183b1b..da357a4 100644
--- a/bootstrap/pkg/core/function.go
+++ b/bootstrap/pkg/core/function.go
@@ -48,8 +48,9 @@ import (
 type nativeFnHandler = func(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IError)
 
 type IFn interface {
-	ast.ILocatable
+	IExpr
 	Apply(rt *Runtime, scope IScope, n Node, args *List) (IExpr, IError)
+	GetName() string
 }
 
 // Function struct represent a user defined function.
@@ -142,8 +143,9 @@ func (f *Function) Apply(rt *Runtime, scope IScope, n Node, args *List) (IExpr,
 
 // MakeFunction Create a function with the given `params` and `body` in
 // the given `scope`.
-func MakeFunction(scope IScope, params IColl, body *Block) *Function {
+func MakeFunction(n Node, scope IScope, params IColl, body *Block) *Function {
 	return &Function{
+		Node:    n,
 		scope:   scope,
 		params:  params,
 		body:    body,
@@ -173,7 +175,8 @@ func MakeFnScope(rt *Runtime, parent IScope, bindings IColl, values IColl) (*Sco
 			fmt.Printf("[DEBUG] Mismatch on bindings and values: Bindings: %s, Values: %s\n", bindings, values)
 		}
 
-		return nil, MakeError(rt,
+		fmt.Println("3333333", values.(IExpr).GetLocation(), bindings.(IExpr).GetLocation())
+		return nil, MakeError(rt, values.(IExpr),
 			fmt.Sprintf("expected '%d' arguments, got '%d'.", bindings.Count(), values.Count()))
 	}
 
@@ -185,20 +188,29 @@ func MakeFnScope(rt *Runtime, parent IScope, bindings IColl, values IColl) (*Sco
 		if binds[i].GetType() == ast.Symbol && binds[i].(*Symbol).IsRestable() {
 
 			if i != len(binds)-1 {
-				return nil, MakeErrorFor(rt, binds[i], "The function argument with '&' has to be the last argument.")
+				return nil, MakeError(rt, binds[i], "The function argument with '&' has to be the last argument.")
 			}
 
 			// if the number of values are one less than the number of bindings
 			// but the last binding is a Restable (e.g &x) the the last bindings
 			// has to be an empty list. Note the check for number of vlaues comes
 			// next.
-			rest := MakeEmptyList()
+			rest := MakeEmptyList(MakeNodeFromExpr(binds[i]))
 
 			if i == len(exprs)-1 {
 				// If the number of values matches the number of bindings
 				// or it is more than that create a list from them
 				// to pass it to the last argument that has to be Restable (e.g &x)
-				rest = MakeList(exprs[i:])
+				elements := exprs[i:]
+				var node Node
+
+				if len(elements) > 0 {
+					node = MakeNodeFromExprs(elements)
+				} else {
+					node = MakeNodeFromExpr(binds[i])
+				}
+
+				rest = MakeList(node, elements)
 			}
 
 			scope.Insert(binds[i].(*Symbol).GetName()[1:], rest, false)
@@ -215,6 +227,10 @@ func (f *NativeFunction) GetType() ast.NodeType {
 	return ast.NativeFn
 }
 
+func (f *NativeFunction) GetName() string {
+	return f.name
+}
+
 func (f *NativeFunction) String() string {
 	return fmt.Sprintf("<NativeFn: %s at %p>", f.name, f)
 }
diff --git a/bootstrap/pkg/core/keyword.go b/bootstrap/pkg/core/keyword.go
index 629bebd..d2a1c39 100644
--- a/bootstrap/pkg/core/keyword.go
+++ b/bootstrap/pkg/core/keyword.go
@@ -159,7 +159,7 @@ func (k *Keyword) Eval(rt *Runtime, scope IScope) (*Keyword, IError) {
 		}
 
 		if aliasedNS == nil {
-			return nil, MakeErrorFor(rt, k, fmt.Sprintf("can't find the alias '%s' in the current namespace.", k.nsName))
+			return nil, MakeError(rt, k, fmt.Sprintf("can't find the alias '%s' in the current namespace.", k.nsName))
 		}
 		k.ns = aliasedNS
 		return k, nil
diff --git a/bootstrap/pkg/core/list.go b/bootstrap/pkg/core/list.go
index e1b744e..1e3c2fc 100644
--- a/bootstrap/pkg/core/list.go
+++ b/bootstrap/pkg/core/list.go
@@ -70,9 +70,16 @@ func (l *List) First() IExpr {
 
 func (l *List) Rest() ISeq {
 	if l.Count() < 2 {
-		return MakeEmptyList()
+		return MakeEmptyList(l.Node)
 	}
-	return MakeList(l.exprs[1:])
+
+	rest := l.exprs[1:]
+	node := l.Node
+	if len(rest) > 0 {
+		node = MakeNodeFromExprs(rest)
+	}
+
+	return MakeList(node, rest)
 }
 
 func (l *List) Hash() uint32 {
@@ -97,8 +104,8 @@ func (l *List) ToSlice() []IExpr {
 }
 
 func (l *List) Cons(e IExpr) IExpr {
-	elems := l.ToSlice()
-	return MakeList(append([]IExpr{e}, elems...))
+	elements := append([]IExpr{e}, l.ToSlice()...)
+	return MakeList(MakeNodeFromExprs(elements), elements)
 }
 
 // END: IColl ---
@@ -118,14 +125,16 @@ func ListStartsWith(l *List, sym string) bool {
 	return false
 }
 
-func MakeList(elements []IExpr) *List {
+func MakeList(n Node, elements []IExpr) *List {
 	return &List{
+		Node:  n,
 		exprs: elements,
 	}
 }
 
-func MakeEmptyList() *List {
+func MakeEmptyList(n Node) *List {
 	return &List{
+		Node:  n,
 		exprs: []IExpr{},
 	}
 }
diff --git a/bootstrap/pkg/core/namespace.go b/bootstrap/pkg/core/namespace.go
index a185ab9..0a2b48e 100644
--- a/bootstrap/pkg/core/namespace.go
+++ b/bootstrap/pkg/core/namespace.go
@@ -56,7 +56,7 @@ func (n *Namespace) GetType() ast.NodeType {
 	return ast.Namespace
 }
 
-func (n *Namespace) GetLocation() ast.Location {
+func (n *Namespace) GetLocation() *ast.Location {
 	return ast.MakeUnknownLocation()
 }
 
@@ -141,7 +141,7 @@ func (n *Namespace) getForms() *Block {
 
 // requireNS finds and loads the namespace addressed by the given
 // `ns` string.
-func requireNS(rt *Runtime, ns string) (*Namespace, IError) {
+func requireNS(rt *Runtime, ns *Symbol) (*Namespace, IError) {
 	// TODO: use a hashing algorithm to avoid reloading an unchanged namespace
 	loadedForms, err := rt.LoadNS(ns)
 
@@ -155,11 +155,12 @@ func requireNS(rt *Runtime, ns string) (*Namespace, IError) {
 	if body.Count() == 0 {
 		return nil, MakeError(
 			rt,
+			body,
 			fmt.Sprintf("The '%s' ns source code doesn't start with an 'ns' form.", ns),
 		)
 	}
 
-	namespace := MakeNS(ns, source)
+	namespace := MakeNS(ns.GetName(), source)
 	namespace.setForms(body)
 
 	return &namespace, nil
@@ -188,21 +189,21 @@ func RequireNamespace(rt *Runtime, namespace IExpr) (IExpr, IError) {
 		first := list.First()
 
 		if first.GetType() != ast.Symbol {
-			return nil, MakeErrorFor(rt, first, "The first element has to be a symbol")
+			return nil, MakeError(rt, first, "The first element has to be a symbol")
 		}
 
 		second := list.Rest().First()
 		if second.GetType() != ast.Symbol {
-			return nil, MakeErrorFor(rt, first, "The second element has to be a symbol")
+			return nil, MakeError(rt, first, "The second element has to be a symbol")
 		}
 
 		ns = first.(*Symbol)
 		alias = second.(*Symbol).GetName()
 	default:
-		return nil, MakeErrorFor(rt, ns, "Don't know how to load the given namespace")
+		return nil, MakeError(rt, ns, "Don't know how to load the given namespace")
 	}
 
-	loadedNS, err := requireNS(rt, ns.GetName())
+	loadedNS, err := requireNS(rt, ns)
 
 	if err != nil {
 		return nil, err
@@ -217,6 +218,7 @@ func RequireNamespace(rt *Runtime, namespace IExpr) (IExpr, IError) {
 	if !inserted {
 		return nil, MakeError(
 			rt,
+			loadedNS,
 			fmt.Sprintf(
 				"the namespace '%s' didn't get inserted in the runtime.",
 				loadedNS.GetName()),
@@ -231,6 +233,7 @@ func RequireNamespace(rt *Runtime, namespace IExpr) (IExpr, IError) {
 	if !inserted {
 		return nil, MakeError(
 			rt,
+			loadedNS,
 			fmt.Sprintf(
 				"can't set the current ns back to '%s' from '%s'.",
 				prevNS.GetName(),
diff --git a/bootstrap/pkg/core/nothing.go b/bootstrap/pkg/core/nothing.go
index cb33351..118ed7f 100644
--- a/bootstrap/pkg/core/nothing.go
+++ b/bootstrap/pkg/core/nothing.go
@@ -36,7 +36,7 @@ func (n NothingType) Hash() uint32 {
 	return hash.HashOf(append([]byte{byte(ast.Block)}, bytes...))
 }
 
-func (n NothingType) GetLocation() ast.Location {
+func (n NothingType) GetLocation() *ast.Location {
 	return ast.MakeUnknownLocation()
 }
 
diff --git a/bootstrap/pkg/core/parser.go b/bootstrap/pkg/core/parser.go
index 10a9554..59234c9 100644
--- a/bootstrap/pkg/core/parser.go
+++ b/bootstrap/pkg/core/parser.go
@@ -33,6 +33,8 @@ package core
 import (
 	"strings"
 	"unicode"
+
+	"serene-lang.org/bootstrap/pkg/ast"
 )
 
 // An array of the valid characters that be be used in a symbol
@@ -57,14 +59,17 @@ type IParsable interface {
 
 	// Returns the current position in the buffer
 	GetLocation() int
+	GetSource() *ast.Source
 	Buffer() *[]string
 }
 
 // StringParser is an implementation of the  IParsable that operates on strings.
 // To put it simply it parses input strings
 type StringParser struct {
-	buffer []string
-	pos    int
+	buffer    []string
+	pos       int
+	source    string
+	lineIndex []int
 }
 
 // Implementing IParsable for StringParser ---
@@ -75,6 +80,12 @@ func (sp *StringParser) next(skipWhitespace bool) *string {
 		return nil
 	}
 	char := sp.buffer[sp.pos]
+
+	if char == "\n" {
+		// Including the \n itself
+		sp.lineIndex = append(sp.lineIndex, sp.pos+1)
+	}
+
 	sp.pos = sp.pos + 1
 
 	if skipWhitespace && isSeparator(&char) {
@@ -127,6 +138,14 @@ func (sp *StringParser) GetLocation() int {
 	return sp.pos
 }
 
+func (sp *StringParser) GetSource() *ast.Source {
+	return &ast.Source{
+		Buffer:    &sp.buffer,
+		Path:      sp.source,
+		LineIndex: &sp.lineIndex,
+	}
+}
+
 func (sp *StringParser) Buffer() *[]string {
 	return &sp.buffer
 }
@@ -136,7 +155,7 @@ func (sp *StringParser) Buffer() *[]string {
 // makeErrorAtPoint is a helper function which generates an `IError` that
 // points at the current position of the buffer.
 func makeErrorAtPoint(p IParsable, msg string, a ...interface{}) IError {
-	n := MakeSinglePointNode(p.Buffer(), p.GetLocation())
+	n := MakeSinglePointNode(p.GetSource(), p.GetLocation())
 	return MakeParsetimeErrorf(n, msg, a...)
 }
 
@@ -207,7 +226,7 @@ func readRawSymbol(parser IParsable) (IExpr, IError) {
 		}
 	}
 
-	node := MakeNode(parser.Buffer(), parser.GetLocation()-len(symbol), parser.GetLocation())
+	node := MakeNode(parser.GetSource(), parser.GetLocation()-len(symbol), parser.GetLocation())
 	sym, err := MakeSymbol(node, symbol)
 
 	if err != nil {
@@ -228,7 +247,7 @@ func readString(parser IParsable) (IExpr, IError) {
 		}
 
 		if *c == "\"" {
-			node := MakeNode(parser.Buffer(), parser.GetLocation()-len(str), parser.GetLocation())
+			node := MakeNode(parser.GetSource(), parser.GetLocation()-len(str), parser.GetLocation())
 			return MakeString(node, str), nil
 		}
 
@@ -367,7 +386,10 @@ func readList(parser IParsable) (IExpr, IError) {
 		}
 	}
 
-	return MakeList(list), nil
+	node := MakeNodeFromExprs(list)
+	node.location.DecStart(1)
+	node.location.IncEnd(1)
+	return MakeList(node, list), nil
 }
 
 func readComment(parser IParsable) (IExpr, IError) {
@@ -387,7 +409,7 @@ func readQuotedExpr(parser IParsable) (IExpr, IError) {
 		return nil, err
 	}
 
-	symNode := MakeNode(parser.Buffer(), parser.GetLocation(), parser.GetLocation())
+	symNode := MakeNode(parser.GetSource(), parser.GetLocation(), parser.GetLocation())
 	sym, err := MakeSymbol(symNode, "quote")
 
 	if err != nil {
@@ -395,10 +417,15 @@ func readQuotedExpr(parser IParsable) (IExpr, IError) {
 		return nil, err
 	}
 
-	return MakeList([]IExpr{
+	listElems := []IExpr{
 		sym,
 		expr,
-	}), nil
+	}
+
+	listNode := MakeNodeFromExprs(listElems)
+	listNode.location.DecStart(1)
+	listNode.location.IncStart(1)
+	return MakeList(listNode, listElems), nil
 }
 
 // readUnquotedExpr reads different unquoting expressions from their short representaions.
@@ -417,7 +444,7 @@ func readUnquotedExpr(parser IParsable) (IExpr, IError) {
 	var err IError
 	var expr IExpr
 
-	node := MakeNode(parser.Buffer(), parser.GetLocation(), parser.GetLocation())
+	node := MakeNode(parser.GetSource(), parser.GetLocation(), parser.GetLocation())
 
 	if *c == "@" {
 		parser.next(true)
@@ -441,7 +468,11 @@ func readUnquotedExpr(parser IParsable) (IExpr, IError) {
 		return nil, err
 	}
 
-	return MakeList([]IExpr{sym, expr}), nil
+	listElems := []IExpr{sym, expr}
+	listNode := MakeNodeFromExprs(listElems)
+	listNode.location.DecStart(1)
+	listNode.location.IncStart(1)
+	return MakeList(listNode, listElems), nil
 }
 
 // readQuasiquotedExpr reads the backquote and replace it with a call
@@ -452,16 +483,19 @@ func readQuasiquotedExpr(parser IParsable) (IExpr, IError) {
 		return nil, err
 	}
 
-	node := MakeNode(parser.Buffer(), parser.GetLocation(), parser.GetLocation())
+	node := MakeNode(parser.GetSource(), parser.GetLocation(), parser.GetLocation())
 	sym, err := MakeSymbol(node, "quasiquote")
 	if err != nil {
 		err.SetNode(&node)
 		return nil, err
 	}
-	return MakeList([]IExpr{
-		sym,
-		expr,
-	}), nil
+
+	listElems := []IExpr{sym, expr}
+	listNode := MakeNodeFromExprs(listElems)
+	listNode.location.DecStart(1)
+	listNode.location.IncStart(1)
+
+	return MakeList(listNode, listElems), nil
 }
 
 // readExpr reads one expression from the input. This function is the most
@@ -516,13 +550,14 @@ loop:
 // by itself is not something available to the language. It's
 // just anbstraction for a ordered collection of expressions.
 // It doesn't have anything to do with the concept of blocks
-// from other programming languages
-func ParseToAST(input string) (*Block, IError) {
+// from other programming languages.
+func ParseToAST(source string, input string) (*Block, IError) {
 
 	var ast Block
 	parser := StringParser{
 		buffer: strings.Split(input, ""),
 		pos:    0,
+		source: source,
 	}
 
 	for {
diff --git a/bootstrap/pkg/core/printer.go b/bootstrap/pkg/core/printer.go
index 462ed08..97fd7a9 100644
--- a/bootstrap/pkg/core/printer.go
+++ b/bootstrap/pkg/core/printer.go
@@ -21,6 +21,8 @@ package core
 import (
 	"fmt"
 	"strings"
+
+	"github.com/gookit/color"
 )
 
 func toRepresanbleString(ast ...IRepresentable) string {
@@ -63,6 +65,36 @@ func Println(rt *Runtime, ast ...IRepresentable) {
 }
 
 func PrintError(rt *Runtime, err IError) {
+	trace := err.GetStackTrace()
+
+	for i, f := range *trace {
+		loc := f.Caller.GetLocation()
+		fmt.Println("===============")
+		fmt.Println(f.Fn.GetLocation())
+		fmt.Println(loc)
+		source := loc.GetSource()
+		// if loc.GetSource().Buffer != nil {
+		// 	fmt.Println(loc.GetSource().LineIndex)
+		// 	source = *loc.GetSource().Buffer
+		// }
+		startline := source.LineNumberFor(loc.GetStart()) - 1
+		endline := source.LineNumberFor(loc.GetEnd()) + 1
+
+		var lines string
+		for i := startline; i <= endline; i++ {
+			lines += fmt.Sprintf("%d:\t%s\n", i, source.GetLine(i))
+		}
+
+		color.Yellow.Printf(
+			"%d: In function '%s' at '%s'\n",
+			i,
+			f.Fn.GetName(),
+			loc.GetSource().Path,
+		)
+		color.White.Printf("%s\n", lines)
+	}
 	loc := err.GetLocation()
-	fmt.Printf("Error: %s\nAt: %d to %d\n", err.String(), loc.GetStart(), loc.GetEnd())
+
+	errTag := color.Red.Sprint("ERROR")
+	fmt.Printf("%s: %s\nAt: %d to %d\n", errTag, err.String(), loc.GetStart(), loc.GetEnd())
 }
diff --git a/bootstrap/pkg/core/quasiquote.go b/bootstrap/pkg/core/quasiquote.go
index ed402cf..53c679e 100644
--- a/bootstrap/pkg/core/quasiquote.go
+++ b/bootstrap/pkg/core/quasiquote.go
@@ -98,10 +98,15 @@ func qqProcess(rt *Runtime, e IExpr) (IExpr, IError) {
 			// newErr.stack(err)
 			return nil, err
 		}
-		return MakeList([]IExpr{
+		elems := []IExpr{
 			sym,
 			e,
-		}), nil
+		}
+
+		return MakeList(
+			MakeNodeFromExprs(elems),
+			elems,
+		), nil
 
 	case ast.List:
 		list := e.(*List)
@@ -125,7 +130,7 @@ func qqProcess(rt *Runtime, e IExpr) (IExpr, IError) {
 		}
 		// ???
 		if isUnquoteSplicing(first) {
-			return nil, MakeErrorFor(rt, first, "'unquote-splicing' is not allowed out of a collection.")
+			return nil, MakeError(rt, first, "'unquote-splicing' is not allowed out of a collection.")
 		}
 
 		// p := list
diff --git a/bootstrap/pkg/core/reader.go b/bootstrap/pkg/core/reader.go
index 3c638d9..040ba88 100644
--- a/bootstrap/pkg/core/reader.go
+++ b/bootstrap/pkg/core/reader.go
@@ -18,6 +18,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 package core
 
-func ReadString(input string) (*Block, IError) {
-	return ParseToAST(input)
+func ReadString(src string, input string) (*Block, IError) {
+	return ParseToAST(src, input)
 }
diff --git a/bootstrap/pkg/core/runtime.go b/bootstrap/pkg/core/runtime.go
index 9aab2cf..bca2701 100644
--- a/bootstrap/pkg/core/runtime.go
+++ b/bootstrap/pkg/core/runtime.go
@@ -147,8 +147,8 @@ func nsNameToPath(ns string) string {
 // LoadNS looks up the namespace specified by the given name `ns`
 // and reads the content as expressions (parse it) and returns the
 // expressions.
-func (r *Runtime) LoadNS(ns string) (*loadedForms, IError) {
-	nsFile := nsNameToPath(ns)
+func (r *Runtime) LoadNS(ns *Symbol) (*loadedForms, IError) {
+	nsFile := nsNameToPath(ns.GetName())
 	for _, loadPath := range r.paths {
 		possibleFile := path.Join(loadPath, nsFile)
 
@@ -167,13 +167,14 @@ func (r *Runtime) LoadNS(ns string) (*loadedForms, IError) {
 		if err != nil {
 			readError := MakeError(
 				r,
+				ns,
 				fmt.Sprintf("error while reading the file at %s", possibleFile),
 			)
 			readError.WithError(err)
 			return nil, readError
 		}
 
-		body, e := ReadString(string(data))
+		body, e := ReadString(possibleFile, string(data))
 		if e != nil {
 			return nil, e
 		}
@@ -182,7 +183,7 @@ func (r *Runtime) LoadNS(ns string) (*loadedForms, IError) {
 	}
 
 	// TODO: Add the load paths to the error message here
-	return nil, MakeError(r, fmt.Sprintf("Can't find the namespace '%s' in any of load paths.", ns))
+	return nil, MakeError(r, ns, fmt.Sprintf("Can't find the namespace '%s' in any of load paths.", ns))
 }
 
 func (r *Runtime) InsertNS(nsName string, ns *Namespace) {
diff --git a/bootstrap/pkg/core/sforms.go b/bootstrap/pkg/core/sforms.go
index b5d2585..aaa806f 100644
--- a/bootstrap/pkg/core/sforms.go
+++ b/bootstrap/pkg/core/sforms.go
@@ -34,7 +34,7 @@ func Def(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 		name := args.First()
 
 		if name.GetType() != ast.Symbol {
-			return nil, MakeError(rt, "the first argument of 'def' has to be a symbol")
+			return nil, MakeError(rt, name, "the first argument of 'def' has to be a symbol")
 		}
 
 		sym := name.(*Symbol)
@@ -55,7 +55,7 @@ func Def(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 		return sym, nil
 	}
 
-	return nil, MakeError(rt, "'def' form need at least 2 arguments")
+	return nil, MakeError(rt, args, "'def' form need at least 2 arguments")
 }
 
 // Def defines a macro in the current namespace. The first
@@ -72,7 +72,7 @@ func DefMacro(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 		name := args.First()
 
 		if name.GetType() != ast.Symbol {
-			return nil, MakeError(rt, "the first argument of 'defmacro' has to be a symbol")
+			return nil, MakeError(rt, name, "the first argument of 'defmacro' has to be a symbol")
 		}
 
 		sym := name.(*Symbol)
@@ -100,21 +100,21 @@ func DefMacro(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 		return macro, nil
 	}
 
-	return nil, MakeError(rt, "'defmacro' form need at least 2 arguments")
+	return nil, MakeError(rt, args, "'defmacro' form need at least 2 arguments")
 }
 
 // Fn defines a function inside the given scope `scope` with the given `args`.
 // `args` contains the arugment list, docstring and body of the function.
 func Fn(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 
-	if args.Count() < 1 {
-		return nil, MakeError(rt, "'fn' needs at least an arguments list")
+	if args.Count() < 2 {
+		return nil, MakeError(rt, args, "'fn' needs at least an arguments list")
 	}
 
 	var params IColl
 	body := MakeEmptyBlock()
 
-	arguments := args.First()
+	arguments := args.Rest().First()
 
 	// TODO: Add vector in here
 	// Or any other icoll
@@ -123,26 +123,26 @@ func Fn(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 	}
 
 	if args.Count() > 1 {
-		body.SetContent(args.Rest().(*List).ToSlice())
+		body.SetContent(args.Rest().Rest().(*List).ToSlice())
 	}
 
-	return MakeFunction(scope, params, body), nil
+	return MakeFunction(MakeNodeFromExpr(args.First()), scope, params, body), nil
 }
 
 func NSForm(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 	if args.Count() == 1 {
-		return nil, MakeErrorFor(rt, args, "namespace's name is missing")
+		return nil, MakeError(rt, args, "namespace's name is missing")
 	}
 
 	name := args.Rest().First()
 
 	if name.GetType() != ast.Symbol {
-		return nil, MakeErrorFor(rt, name, "the first argument to the 'ns' has to be a symbol")
+		return nil, MakeError(rt, name, "the first argument to the 'ns' has to be a symbol")
 	}
 	nsName := name.(*Symbol).GetName()
 
 	if nsName != rt.CurrentNS().GetName() {
-		return nil, MakeErrorFor(
+		return nil, MakeError(
 			rt,
 			args,
 			fmt.Sprintf("the namespace '%s' doesn't match the file name.", nsName),
@@ -151,7 +151,7 @@ func NSForm(rt *Runtime, scope IScope, args *List) (IExpr, IError) {
 	ns, ok := rt.GetNS(nsName)
 
 	if !ok {
-		return nil, MakeErrorFor(rt, name, fmt.Sprintf("can't find the namespace '%s'. Is it the same as the file name?", nsName))
+		return nil, MakeError(rt, name, fmt.Sprintf("can't find the namespace '%s'. Is it the same as the file name?", nsName))
 	}
 
 	return ns, nil
diff --git a/bootstrap/pkg/core/types.go b/bootstrap/pkg/core/types.go
index a176d52..78ac526 100644
--- a/bootstrap/pkg/core/types.go
+++ b/bootstrap/pkg/core/types.go
@@ -81,8 +81,8 @@ type Node struct {
 }
 
 // GetLocation returns the location of the Node in the source input
-func (n Node) GetLocation() ast.Location {
-	return n.location
+func (n Node) GetLocation() *ast.Location {
+	return &n.location
 }
 
 type ExecutionScope struct {
@@ -123,9 +123,9 @@ func toRepresentables(ast IColl) []IRepresentable {
 }
 
 // MakeNodeFromLocation creates a new Node for the given Location `loc`
-func MakeNodeFromLocation(loc ast.Location) Node {
+func MakeNodeFromLocation(loc *ast.Location) Node {
 	return Node{
-		location: loc,
+		location: *loc,
 	}
 }
 
@@ -136,14 +136,30 @@ func MakeNodeFromExpr(e IExpr) Node {
 	return MakeNodeFromLocation(e.GetLocation())
 }
 
+// MakeNodeFromExprs creates a new Node from the given slice of `IExpr`s.
+// We use the Node to pass it to other IExpr constructors to
+// keep the reference to the original form in the input string
+func MakeNodeFromExprs(es []IExpr) Node {
+	if len(es) == 0 {
+		// TODO: This is temporary, fix it.
+		panic("can't create a node from empty elements.")
+	}
+
+	firstLoc := es[0].GetLocation()
+	endLoc := es[len(es)-1].GetLocation()
+	loc := ast.MakeLocation(firstLoc.GetSource(), firstLoc.GetStart(), endLoc.GetEnd())
+
+	return MakeNodeFromLocation(loc)
+}
+
 // MakeNode creates a new Node in the the given `input` that points to a
 // range of characters starting from the `start` till the `end`.
-func MakeNode(input *[]string, start int, end int) Node {
+func MakeNode(input *ast.Source, start int, end int) Node {
 	return MakeNodeFromLocation(ast.MakeLocation(input, start, end))
 }
 
 // MakeSinglePointNode creates a not the points to a single char in the
 // input
-func MakeSinglePointNode(input *[]string, point int) Node {
+func MakeSinglePointNode(input *ast.Source, point int) Node {
 	return MakeNode(input, point, point)
 }
diff --git a/dev.org b/dev.org
index f6e9ede..0d387f0 100644
--- a/dev.org
+++ b/dev.org
@@ -35,6 +35,7 @@ https://www.reddit.com/r/ProgrammingLanguages/comments/8ggx2n/is_llvm_a_good_bac
 - Official LLVM tutorial C++ :: https://llvm.org/docs/tutorial/
 - Interactive C++ with Cling :: https://blog.llvm.org/posts/2020-11-30-interactive-cpp-with-cling/
 - My First LLVM Compiler :: https://www.wilfred.me.uk/blog/2015/02/21/my-first-llvm-compiler/
+- A Complete Guide to LLVM for Programming Language Creators :: https://mukulrathi.co.uk/create-your-own-programming-language/llvm-ir-cpp-api-tutorial/
 ** Data structures
 - Pure functional datastructures papaer :: https://www.cs.cmu.edu/~rwh/theses/okasaki.pdf
 - Dynamic typing: syntax and proof theory :: https://reader.elsevier.com/reader/sd/pii/0167642394000042?token=CEFF5C5D1B03FD680762FC4889A14C0CA2BB28FE390EC51099984536E12AC358F3D28A5C25C274296ACBBC32E5AE23CD