From c0fad363ab2854008fab8e3dca16b605ef63635c Mon Sep 17 00:00:00 2001
From: Kyle McLamb <kjmclamb@gmail.com>
Date: Mon, 14 Oct 2019 04:10:41 -0400
Subject: [PATCH 1/2] Support positive sign in scientific notation

---
 doc/site/values.markdown                            |  2 ++
 src/vm/wren_compiler.c                              | 13 ++++++++-----
 test/language/number/scientific_literals.wren       |  1 +
 .../number/scientific_multiple_exponent_signs.wren  |  1 +
 4 files changed, 12 insertions(+), 5 deletions(-)
 create mode 100644 test/language/number/scientific_multiple_exponent_signs.wren

diff --git a/doc/site/values.markdown b/doc/site/values.markdown
index cc2181369..4c8dfe05d 100644
--- a/doc/site/values.markdown
+++ b/doc/site/values.markdown
@@ -26,6 +26,8 @@ from other languages:
     3.14159
     1.0
     -12.34
+    0.0314159e02
+    314.159e-02
 
 Numbers are instances of the [Num][] class.
 
diff --git a/src/vm/wren_compiler.c b/src/vm/wren_compiler.c
index caa63534d..6039145f2 100644
--- a/src/vm/wren_compiler.c
+++ b/src/vm/wren_compiler.c
@@ -758,18 +758,21 @@ static void readNumber(Parser* parser)
     nextChar(parser);
     while (isDigit(peekChar(parser))) nextChar(parser);
   }
-  
+
   // See if the number is in scientific notation.
   if (matchChar(parser, 'e') || matchChar(parser, 'E'))
   {
-    // Allow a negative exponent.
-    matchChar(parser, '-');
-    
+    // Allow a single positive/negative exponent symbol.
+    if(!matchChar(parser, '+'))
+    {
+      matchChar(parser, '-');
+    }
+
     if (!isDigit(peekChar(parser)))
     {
       lexError(parser, "Unterminated scientific notation.");
     }
-    
+
     while (isDigit(peekChar(parser))) nextChar(parser);
   }
 
diff --git a/test/language/number/scientific_literals.wren b/test/language/number/scientific_literals.wren
index 526950689..21aa9de4b 100644
--- a/test/language/number/scientific_literals.wren
+++ b/test/language/number/scientific_literals.wren
@@ -7,3 +7,4 @@ System.print(2.55e-2 is Num) // expect: true
 System.print(x is Num) // expect: true
 System.print(-2.55e2) // expect: -255
 System.print(-25500e-2) // expect: -255
+System.print(2.55e+2) // expect: 255
diff --git a/test/language/number/scientific_multiple_exponent_signs.wren b/test/language/number/scientific_multiple_exponent_signs.wren
new file mode 100644
index 000000000..b61bde34c
--- /dev/null
+++ b/test/language/number/scientific_multiple_exponent_signs.wren
@@ -0,0 +1 @@
+var x = 1e+-01 // expect error

From 41e68607758ae7444b53a5b42b8fefd52d99e155 Mon Sep 17 00:00:00 2001
From: Kyle McLamb <kjmclamb@gmail.com>
Date: Thu, 17 Oct 2019 00:12:52 -0400
Subject: [PATCH 2/2] Add exponent with positive sign to docs

---
 doc/site/values.markdown | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/site/values.markdown b/doc/site/values.markdown
index 4c8dfe05d..bb405b898 100644
--- a/doc/site/values.markdown
+++ b/doc/site/values.markdown
@@ -27,6 +27,7 @@ from other languages:
     1.0
     -12.34
     0.0314159e02
+    0.0314159e+02
     314.159e-02
 
 Numbers are instances of the [Num][] class.