Add all the files from the interpreter repo

Signed-off-by: jmug <u.g.a.mariano@gmail.com>

pkg/repl/repl.go

@@ -0,0 +1,59 @@
+package repl
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+
+	"code.jmug.me/jmug/interpreter-in-go/pkg/evaluator"
+	"code.jmug.me/jmug/interpreter-in-go/pkg/lexer"
+	"code.jmug.me/jmug/interpreter-in-go/pkg/object"
+	"code.jmug.me/jmug/interpreter-in-go/pkg/parser"
+)
+
+const PROMPT = ">> "
+
+func Start(in io.Reader, out io.Writer) {
+	scanner := bufio.NewScanner(in)
+	env := object.NewEnvironment()
+	for {
+		fmt.Fprint(out, PROMPT)
+		if !scanner.Scan() {
+			return
+		}
+		l := lexer.New(scanner.Text())
+		p := parser.New(l)
+		program := p.ParseProgram()
+		if len(p.Errors()) != 0 {
+			printParserErrors(out, p.Errors())
+			continue
+		}
+		res := evaluator.Eval(program, env)
+		if res != nil {
+			io.WriteString(out, res.Inspect())
+			io.WriteString(out, "\n")
+		}
+	}
+}
+
+const MONKEY_FACE = `            __,__
+   .--.  .-"     "-.  .--.
+  / .. \/  .-. .-.  \/ .. \
+ | |  '|  /   Y   \  |'  | |
+ | \   \  \ 0 | 0 /  /   / |
+  \ '- ,\.-"""""""-./, -' /
+   ''-' /_   ^ ^   _\ '-''
+       |  \._   _./  |
+       \   \ '~' /   /
+        '._ '-=-' _.'
+           '-----'
+`
+
+func printParserErrors(out io.Writer, errors []string) {
+	io.WriteString(out, MONKEY_FACE)
+	io.WriteString(out, "Woops! We ran into some monkey business here!\n")
+	io.WriteString(out, " parser errors:\n")
+	for _, msg := range errors {
+		io.WriteString(out, "\t"+msg+"\n")
+	}
+}