From 8a5d7ab5d3c83b846cb1ea7150daf202cb5d0373 Mon Sep 17 00:00:00 2001
From: oabrivard <olivier@abrivard.fr>
Date: Wed, 27 Sep 2023 09:55:41 +0200
Subject: [PATCH] Added lexing of LAMBDA to monkey1 version

---
 monkey1/lexer/lexer.go      |  9 ++++++++-
 monkey1/lexer/lexer_test.go | 16 ++++++++++++++++
 monkey1/token/token.go      |  2 ++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/monkey1/lexer/lexer.go b/monkey1/lexer/lexer.go
index 3613013..45e72e2 100644
--- a/monkey1/lexer/lexer.go
+++ b/monkey1/lexer/lexer.go
@@ -33,7 +33,14 @@ func (l *Lexer) NextToken() token.Token {
 	case '+':
 		tok = newToken(token.PLUS, l.ch)
 	case '-':
-		tok = newToken(token.MINUS, l.ch)
+		if l.peekChar() == '>' {
+			ch := l.ch
+			l.readChar()
+			literal := string(ch) + string(l.ch)
+			tok = token.Token{Type: token.LAMBDA, Literal: literal}
+		} else {
+			tok = newToken(token.MINUS, l.ch)
+		}
 	case '!':
 		if l.peekChar() == '=' {
 			ch := l.ch
diff --git a/monkey1/lexer/lexer_test.go b/monkey1/lexer/lexer_test.go
index 17d1aca..7d4fd99 100644
--- a/monkey1/lexer/lexer_test.go
+++ b/monkey1/lexer/lexer_test.go
@@ -14,6 +14,8 @@ let add = fn(x, y) {
   x + y;
 };
 
+let addlambda = fn(x,y) -> x + y;
+
 let result = add(five, ten);
 !-/*5;
 5 < 10 > 5;
@@ -59,6 +61,20 @@ if (5 < 10) {
 		{token.RBRACE, "}"},
 		{token.SEMICOLON, ";"},
 		{token.LET, "let"},
+		{token.IDENT, "addlambda"},
+		{token.ASSIGN, "="},
+		{token.FUNCTION, "fn"},
+		{token.LPAREN, "("},
+		{token.IDENT, "x"},
+		{token.COMMA, ","},
+		{token.IDENT, "y"},
+		{token.RPAREN, ")"},
+		{token.LAMBDA, "->"},
+		{token.IDENT, "x"},
+		{token.PLUS, "+"},
+		{token.IDENT, "y"},
+		{token.SEMICOLON, ";"},
+		{token.LET, "let"},
 		{token.IDENT, "result"},
 		{token.ASSIGN, "="},
 		{token.IDENT, "add"},
diff --git a/monkey1/token/token.go b/monkey1/token/token.go
index 12158fa..029a392 100644
--- a/monkey1/token/token.go
+++ b/monkey1/token/token.go
@@ -33,6 +33,8 @@ const (
 	LBRACE = "{"
 	RBRACE = "}"
 
+	LAMBDA = "->"
+
 	// Keywords
 	FUNCTION = "FUNCTION"
 	LET      = "LET"