Merge pull request #176 from plaid/dc-trim

string: add S.trim

index.js

@@ -2919,6 +2919,20 @@
       [$.String, $.String],
       function(s) { return s.toLowerCase(); });
 
+  //# trim :: String -> String
+  //.
+  //. Strips leading and trailing whitespace characters.
+  //.
+  //. ```javascript
+  //. > S.trim('\t\t foo bar \n')
+  //. 'foo bar'
+  //. ```
+  S.trim =
+  def('trim',
+      {},
+      [$.String, $.String],
+      R.trim);
+
   //# words :: String -> [String]
   //.
   //. Takes a string and returns the list of words the string contains

test/index.js

@@ -5553,6 +5553,39 @@ describe('string', function() {
 
   });
 
+  describe('trim', function() {
+
+    it('is a unary function', function() {
+      eq(typeof S.trim, 'function');
+      eq(S.trim.length, 1);
+    });
+
+    it('type checks its arguments', function() {
+      throws(function() { S.trim(/XXX/); },
+             errorEq(TypeError,
+                     'Invalid value\n' +
+                     '\n' +
+                     'trim :: String -> String\n' +
+                     '        ^^^^^^\n' +
+                     '          1\n' +
+                     '\n' +
+                     '1)  /XXX/ :: RegExp\n' +
+                     '\n' +
+                     'The value at position 1 is not a member of ‘String’.\n'));
+    });
+
+    it('strips leading and trailing whitespace characters', function() {
+      eq(S.trim(''), '');
+      eq(S.trim(' '), '');
+      eq(S.trim('x'), 'x');
+      eq(S.trim(' x'), 'x');
+      eq(S.trim('x '), 'x');
+      eq(S.trim(' x '), 'x');
+      eq(S.trim('\n\r\t x \n\r\t x \n\r\t'), 'x \n\r\t x');
+    });
+
+  });
+
   describe('words', function() {
 
     it('is a unary function', function() {