2021-02-14 02:09:56 +00:00
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package main
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import "fmt"
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// Builtins is a handy holder for our various default words
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type Builtins struct{}
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2021-02-14 02:37:56 +00:00
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// ErrExit is a special sentinel value to cease computation and quit
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var ErrExit = fmt.Errorf("exit requested")
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2021-02-14 02:09:56 +00:00
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// Add sums the top two numbers on the stack and pushes the result
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func (b *Builtins) Add(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r1 + r2)
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return nil
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}
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}
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// Sub performs NOS - TOS and pushes the result
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func (b *Builtins) Sub(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r2 - r1)
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return nil
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}
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}
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// Mul multiplies the two numbers on the top of the stack and pushes the result
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func (b *Builtins) Mul(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r2 * r1)
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return nil
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}
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}
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// Div performs NOS/TOS and pushes the (integer!) result
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func (b *Builtins) Div(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r2 / r1)
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return nil
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}
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}
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// Print pops the stack and outputs it to stdout
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func (b *Builtins) Print(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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fmt.Print(r1, " ")
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return nil
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}
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}
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// Dup pops the stack, then pushes two copies onto the stack
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func (b *Builtins) Dup(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r1)
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s.Push(r1)
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return nil
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}
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}
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// Swap inverts the order of TOS and NOS
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func (b *Builtins) Swap(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r1)
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s.Push(r2)
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return nil
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}
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}
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// Over duplicates NOS to TOS, resulting in NOS TOS NOS
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func (b *Builtins) Over(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r2)
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s.Push(r1)
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s.Push(r2)
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return nil
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}
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}
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// Drop simply discards TOS
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func (b *Builtins) Drop(s *Stack) func() error {
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return func() error {
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_, err := s.Pop()
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return err
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}
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}
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// Rot cycles the first three items on the stack: TOS 1 2 3 -> TOS 3 1 2
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func (b *Builtins) Rot(s *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r2, err := s.Pop()
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if err != nil {
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return err
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}
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r3, err := s.Pop()
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if err != nil {
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return err
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}
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s.Push(r2)
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s.Push(r1)
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s.Push(r3)
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return err
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}
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}
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// Words outputs a list of all known words in the dictionary
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func (b *Builtins) Words(d Dictionary) func() error {
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return func() error {
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for n := range d {
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fmt.Printf("%s ", n)
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}
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return nil
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}
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}
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2021-02-14 02:37:56 +00:00
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// Emit outputs the UTF-8 rune for the int on the top of the stack
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func (b *Builtins) Emit(s *Stack) func() error {
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return func() error {
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i, err := s.Pop()
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if err != nil {
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return err
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}
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fmt.Print(string(rune(i)) + " ")
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return nil
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}
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}
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2021-02-14 16:58:43 +00:00
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// ToR pops from the stack to the return stack
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func (b *Builtins) ToR(s *Stack, r *Stack) func() error {
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return func() error {
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r1, err := s.Pop()
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if err != nil {
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return err
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}
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r.Push(r1)
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return nil
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}
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}
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// RFrom pops from the return stack to the stack
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func (b *Builtins) RFrom(s *Stack, r *Stack) func() error {
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return func() error {
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r1, err := r.Pop()
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if err != nil {
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return err
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}
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s.Push(r1)
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return nil
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}
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}
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// RFetch copies from the return stack to the stack
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func (b *Builtins) RFetch(s *Stack, r *Stack) func() error {
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return func() error {
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r1, err := r.Pop()
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if err != nil {
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return err
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}
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r.Push(r1)
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s.Push(r1)
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return nil
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}
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}
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2021-02-14 02:09:56 +00:00
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// CR prints a newline to standard out
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func (b *Builtins) CR() func() error {
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return func() error {
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fmt.Print("\n")
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return nil
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}
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}
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2021-02-14 02:37:56 +00:00
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// Quit exits the repl
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func (b *Builtins) Quit() func() error {
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return func() error {
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return ErrExit
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}
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}
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2021-02-14 02:09:56 +00:00
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// Debug prints the stack without modifying it
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func (b *Builtins) Debug(s *Stack) func() error {
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return func() error {
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fmt.Print(s.values, " ")
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return nil
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}
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}
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