From 25baaf00896c363eb9529652ce0c479df2b1915b Mon Sep 17 00:00:00 2001
From: David Chambers <dc@davidchambers.me>
Date: Thu, 16 Jul 2020 19:30:00 +0200
Subject: [PATCH] types: define Buffer

---
 index.js      | 16 ++++++++++++++++
 test/index.js | 22 ++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/index.js b/index.js
index 221a25a..5037086 100644
--- a/index.js
+++ b/index.js
@@ -615,6 +615,18 @@
     ([])
     (typeofEq ('boolean'));
 
+  //# Buffer :: Type
+  //.
+  //. Type comprising every [Buffer][] object.
+  var Buffer_ = NullaryTypeWithUrl
+    ('Buffer')
+    ([])
+    (function(x) {
+       return typeof Buffer !== 'undefined' &&
+              // eslint-disable-next-line no-undef
+              Buffer.isBuffer (x);
+     });
+
   //# Date :: Type
   //.
   //. Type comprising every Date value.
@@ -1054,6 +1066,7 @@
   //.   - <code>[Array](#Array) ([Unknown][])</code>
   //.   - <code>[Array2](#Array2) ([Unknown][]) ([Unknown][])</code>
   //.   - <code>[Boolean](#Boolean)</code>
+  //.   - <code>[Buffer](#Buffer)</code>
   //.   - <code>[Date](#Date)</code>
   //.   - <code>[Descending](#Descending) ([Unknown][])</code>
   //.   - <code>[Either](#Either) ([Unknown][]) ([Unknown][])</code>
@@ -1082,6 +1095,7 @@
     Array_ (Unknown),
     Array2 (Unknown) (Unknown),
     Boolean_,
+    Buffer_,
     Date_,
     Descending (Unknown),
     Either_ (Unknown) (Unknown),
@@ -2823,6 +2837,7 @@
     Array1: fromUncheckedUnaryType (Array1),
     Array2: fromUncheckedBinaryType (Array2),
     Boolean: Boolean_,
+    Buffer: Buffer_,
     Date: Date_,
     ValidDate: ValidDate,
     Descending: fromUncheckedUnaryType (Descending),
@@ -2974,6 +2989,7 @@
 
 }));
 
+//. [Buffer]:               https://nodejs.org/api/buffer.html#buffer_buffer
 //. [Descending]:           v:sanctuary-js/sanctuary-descending
 //. [Either]:               v:sanctuary-js/sanctuary-either
 //. [FL:Semigroup]:         https://github.com/fantasyland/fantasy-land#semigroup
diff --git a/test/index.js b/test/index.js
index be3ab32..1dff121 100644
--- a/test/index.js
+++ b/test/index.js
@@ -88,6 +88,7 @@ suite ('env', () => {
          $.Array ($.Unknown),
          $.Array2 ($.Unknown) ($.Unknown),
          $.Boolean,
+         $.Buffer,
          $.Date,
          $.Descending ($.Unknown),
          $.Either ($.Unknown) ($.Unknown),
@@ -1552,6 +1553,27 @@ See https://github.com/sanctuary-js/sanctuary-def/tree/v${version}#Array2 for in
     eq ($.Boolean.supertypes) ([]);
   });
 
+  test ('provides the "Buffer" type', () => {
+    eq ($.Buffer.name) ('Buffer');
+    eq ($.Buffer.url) (`https://github.com/sanctuary-js/sanctuary-def/tree/v${version}#Buffer`);
+    eq ($.Buffer.supertypes) ([]);
+
+    const isBuffer = $.test ([]) ($.Buffer);
+    eq (isBuffer (null)) (false);
+    eq (isBuffer (Buffer.from ([1, 2, 3]))) (true);
+
+    {
+      const Buffer = global.Buffer;
+      delete global.Buffer;
+      try {
+        eq (isBuffer (null)) (false);
+        eq (isBuffer (Buffer.from ([1, 2, 3]))) (false);
+      } finally {
+        global.Buffer = Buffer;
+      }
+    }
+  });
+
   test ('provides the "Date" type', () => {
     eq ($.Date.name) ('Date');
     eq ($.Date.url) (`https://github.com/sanctuary-js/sanctuary-def/tree/v${version}#Date`);