Change type validators to use predicate instead of TypeRep

This commit will close #149 by changing all functions that have built-in type validation to use predicates instead of TypeReps to perform their validations. The functions affected are: * get() * gets() * pluck() * parseJson() The only function untouched is `is()`, for it is used to turn a TypeRep into a predicate.
sanctuary-js · Apr 23, 2016 · c30cbbd · c30cbbd
1 parent e3c2db2
commit c30cbbd
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diff --git a/index.js b/index.js
@@ -411,7 +411,7 @@
   //. > S.is(String, 42)
   //. false
   //. ```
-  var is = S.is =
+  S.is =
   def('is',
       {},
       [TypeRep, $.Any, $.Boolean],
@@ -2341,25 +2341,24 @@
   //. ```
   S.lastIndexOf = sanctifyIndexOf('lastIndexOf');
 
-  //# pluck :: Accessible a => TypeRep b -> String -> [a] -> [Maybe b]
+  //# pluck :: Accessible a => (b -> Boolean) -> String -> [a] -> [Maybe c]
   //.
-  //. Takes a [type representative](#type-representatives), a property name,
-  //. and a list of objects and returns a list of equal length. Each element
-  //. of the output list is Just the value of the specified property of the
-  //. corresponding object if the value is of the specified type (according
-  //. to [`is`](#is)); Nothing otherwise.
+  //. Takes a predicate, a property name, and a list of objects and returns a
+  //. list of equal length. Each element of the output list is Just the value of
+  //. the specified property of the corresponding object if the value passes the
+  //. given predicate; Nothing otherwise.
   //.
   //. See also [`get`](#get).
   //.
   //. ```javascript
-  //. > S.pluck(Number, 'x', [{x: 1}, {x: 2}, {x: '3'}, {x: null}, {}])
+  //. > S.pluck(S.is(Number), 'x', [{x: 1}, {x: 2}, {x: '3'}, {x: null}, {}])
   //. [Just(1), Just(2), Nothing(), Nothing(), Nothing()]
   //. ```
   S.pluck =
   def('pluck',
       {a: [Accessible]},
-      [TypeRep, $.String, $.Array(a), $.Array($Maybe(b))],
-      function(type, key, xs) { return R.map(get(type, key), xs); });
+      [$.Function, $.String, $.Array(a), $.Array($Maybe(c))],
+      function(pred, key, xs) { return R.map(get(pred, key), xs); });
 
   //# reduce :: Foldable f => (a -> b -> a) -> a -> f b -> a
   //.
@@ -2440,66 +2439,61 @@
   //. ```
   S.prop = prop;
 
-  //# get :: Accessible a => TypeRep b -> String -> a -> Maybe b
+  //# get :: Accessible a => (b -> Boolean) -> String -> a -> Maybe c
   //.
-  //. Takes a [type representative](#type-representatives), a property
-  //. name, and an object and returns Just the value of the specified object
-  //. property if it is of the specified type (according to [`is`](#is));
+  //. Takes a predicate, a property name, and an object and returns Just the
+  //. value of the specified object property if passes the given predicate;
   //. Nothing otherwise.
   //.
-  //. The `Object` type representative may be used as a catch-all since most
-  //. values have `Object.prototype` in their prototype chains.
-  //.
   //. See also [`gets`](#gets) and [`prop`](#prop).
   //.
   //. ```javascript
-  //. > S.get(Number, 'x', {x: 1, y: 2})
+  //. > S.get(S.is(Number), 'x', {x: 1, y: 2})
   //. Just(1)
   //.
-  //. > S.get(Number, 'x', {x: '1', y: '2'})
+  //. > S.get(S.is(Number), 'x', {x: '1', y: '2'})
   //. Nothing()
   //.
-  //. > S.get(Number, 'x', {})
+  //. > S.get(S.is(Number), 'x', {})
   //. Nothing()
   //. ```
   var get = S.get =
   def('get',
       {a: [Accessible]},
-      [TypeRep, $.String, a, $Maybe(b)],
-      function(type, key, obj) { return filter(is(type), Just(obj[key])); });
+      [$.Function, $.String, a, $Maybe(c)],
+      function(pred, key, obj) { return filter(pred, Just(obj[key])); });
 
-  //# gets :: Accessible a => TypeRep b -> [String] -> a -> Maybe b
+  //# gets :: Accessible a => (b -> Boolean) -> [String] -> a -> Maybe c
   //.
-  //. Takes a [type representative](#type-representatives), a list of property
-  //. names, and an object and returns Just the value at the path specified by
-  //. the list of property names if such a path exists and the value is of the
-  //. specified type; Nothing otherwise.
+  //. Takes a predicate, a list of property names, and an object and returns
+  //. Just the value at the path specified by the list of property names if such
+  //. a path exists and the value passes the given predicate; Nothing otherwise.
   //.
   //. See also [`get`](#get).
   //.
   //. ```javascript
-  //. > S.gets(Number, ['a', 'b', 'c'], {a: {b: {c: 42}}})
+  //. > S.gets(S.is(Number), ['a', 'b', 'c'], {a: {b: {c: 42}}})
   //. Just(42)
   //.
-  //. > S.gets(Number, ['a', 'b', 'c'], {a: {b: {c: '42'}}})
+  //. > S.gets(S.is(Number), ['a', 'b', 'c'], {a: {b: {c: '42'}}})
   //. Nothing()
   //.
-  //. > S.gets(Number, ['a', 'b', 'c'], {})
+  //. > S.gets(S.is(Number), ['a', 'b', 'c'], {})
   //. Nothing()
   //. ```
   S.gets =
   def('gets',
       {a: [Accessible]},
-      [TypeRep, $.Array($.String), a, $Maybe(b)],
-      function(type, keys, obj) {
+      [$.Function, $.Array($.String), a, $Maybe(c)],
+      function(pred, keys, obj) {
         var x = obj;
         for (var idx = 0; idx < keys.length; idx += 1) {
           if (x == null) {
             return Nothing();
           }
           x = x[keys[idx]];
         }
-        return filter(is(type), Just(x));
+        return filter(pred, Just(x));
       });
 
   //. ### Number
@@ -2814,28 +2808,27 @@
         )(s);
       });
 
-  //# parseJson :: TypeRep a -> String -> Maybe a
+  //# parseJson :: (a -> Boolean) -> String -> Maybe b
   //.
-  //. Takes a [type representative](#type-representatives) and a string which
-  //. may or may not be valid JSON, and returns Just the result of applying
-  //. `JSON.parse` to the string *if* the result is of the specified type
-  //. (according to [`is`](#is)); Nothing otherwise.
+  //. Takes a predicate and a string which may or may not be valid JSON, and
+  //. returns Just the result of applying `JSON.parse` to the string *if* the
+  //. result passes the predicate; Nothing otherwise.
   //.
   //. ```javascript
-  //. > S.parseJson(Array, '["foo","bar","baz"]')
+  //. > S.parseJson(S.is(Array), '["foo","bar","baz"]')
   //. Just(['foo', 'bar', 'baz'])
   //.
-  //. > S.parseJson(Array, '[')
+  //. > S.parseJson(S.is(Array), '[')
   //. Nothing()
   //.
-  //. > S.parseJson(Object, '["foo","bar","baz"]')
+  //. > S.parseJson(S.is(Object), '["foo","bar","baz"]')
   //. Nothing()
   //. ```
   S.parseJson =
   def('parseJson',
       {},
-      [TypeRep, $.String, $Maybe(a)],
-      function(type, s) { return filter(is(type), encase(JSON.parse, s)); });
+      [$.Function, $.String, $Maybe(b)],
+      function(pred, s) { return filter(pred, encase(JSON.parse, s)); });
 
   //. ### RegExp
 

diff --git a/test/get.js b/test/get.js
@@ -1,10 +1,11 @@
 'use strict';
 var throws = require('assert').throws;
-var vm = require('vm');
 
 var eq = require('./utils').eq;
 var errorEq = require('./utils').errorEq;
 var S = require('..');
+var T = function() { return true; };
+var F = function() { return false; };
 
 
 describe('get', function() {
@@ -19,56 +20,59 @@ describe('get', function() {
            errorEq(TypeError,
                    'Invalid value\n' +
                    '\n' +
-                   'get :: Accessible a => TypeRep -> String -> a -> Maybe b\n' +
-                   '                       ^^^^^^^\n' +
+                   'get :: Accessible a => Function -> String -> a -> Maybe c\n' +
+                   '                       ^^^^^^^^\n' +
                    '                          1\n' +
                    '\n' +
                    '1)  [1, 2, 3] :: Array Number, Array FiniteNumber, Array NonZeroFiniteNumber, Array Integer, Array ValidNumber\n' +
                    '\n' +
-                   'The value at position 1 is not a member of ‘TypeRep’.\n'));
+                   'The value at position 1 is not a member of ‘Function’.\n'));
 
-    throws(function() { S.get(Number, [1, 2, 3]); },
+    throws(function() { S.get(T, [1, 2, 3]); },
            errorEq(TypeError,
                    'Invalid value\n' +
                    '\n' +
-                   'get :: Accessible a => TypeRep -> String -> a -> Maybe b\n' +
-                   '                                  ^^^^^^\n' +
-                   '                                    1\n' +
+                   'get :: Accessible a => Function -> String -> a -> Maybe c\n' +
+                   '                                   ^^^^^^\n' +
+                   '                                     1\n' +
                    '\n' +
                    '1)  [1, 2, 3] :: Array Number, Array FiniteNumber, Array NonZeroFiniteNumber, Array Integer, Array ValidNumber\n' +
                    '\n' +
                    'The value at position 1 is not a member of ‘String’.\n'));
 
-    throws(function() { S.get(Number, 'x', null); },
+    throws(function() { S.get(T, 'x', null); },
            errorEq(TypeError,
                    'Type-class constraint violation\n' +
                    '\n' +
-                   'get :: Accessible a => TypeRep -> String -> a -> Maybe b\n' +
-                   '       ^^^^^^^^^^^^                         ^\n' +
-                   '                                            1\n' +
+                   'get :: Accessible a => Function -> String -> a -> Maybe c\n' +
+                   '       ^^^^^^^^^^^^                          ^\n' +
+                   '                                             1\n' +
                    '\n' +
                    '1)  null :: Null\n' +
                    '\n' +
                    '‘get’ requires ‘a’ to satisfy the Accessible type-class constraint; the value at position 1 does not.\n'));
   });
 
-  it('returns a Maybe', function() {
-    var obj = {x: 0, y: 42};
-    eq(S.get(Number, 'x', obj), S.Just(0));
-    eq(S.get(Number, 'y', obj), S.Just(42));
-    eq(S.get(Number, 'z', obj), S.Nothing());
-    eq(S.get(String, 'x', obj), S.Nothing());
+  it('returns Nothing if the predicate returns false', function() {
+    eq(S.get(F, 'x', {x: 1}), S.Nothing());
+  });
+
+  it('returns Just if the predicate returns true', function() {
+    eq(S.get(T, 'x', {x: 1}), S.Just(1));
   });
 
-  it('does not rely on constructor identity', function() {
-    eq(S.get(RegExp, 'x', {x: vm.runInNewContext('/.*/')}), S.Just(/.*/));
-    eq(S.get(vm.runInNewContext('RegExp'), 'x', {x: /.*/}), S.Just(/.*/));
+  it('returns a Maybe', function() {
+    var obj = {x: 0, y: 42};
+    eq(S.get(S.is(Number), 'x', obj), S.Just(0));
+    eq(S.get(S.is(Number), 'y', obj), S.Just(42));
+    eq(S.get(S.is(Number), 'z', obj), S.Nothing());
+    eq(S.get(S.is(String), 'x', obj), S.Nothing());
   });
 
   it('is curried', function() {
-    eq(S.get(Number).length, 2);
-    eq(S.get(Number)('x').length, 1);
-    eq(S.get(Number)('x')({x: 42}), S.Just(42));
+    eq(S.get(T).length, 2);
+    eq(S.get(T)('x').length, 1);
+    eq(S.get(T)('x')({x: 42}), S.Just(42));
   });
 
 });
diff --git a/test/gets.js b/test/gets.js
@@ -1,11 +1,12 @@
 'use strict';
 
 var throws = require('assert').throws;
-var vm = require('vm');
 
 var eq = require('./utils').eq;
 var errorEq = require('./utils').errorEq;
 var S = require('..');
+var T = function() { return true; };
+var F = function() { return false; };
 
 
 describe('gets', function() {
@@ -20,59 +21,64 @@ describe('gets', function() {
            errorEq(TypeError,
                    'Invalid value\n' +
                    '\n' +
-                   'gets :: Accessible a => TypeRep -> Array String -> a -> Maybe b\n' +
-                   '                        ^^^^^^^\n' +
+                   'gets :: Accessible a => Function -> Array String -> a -> Maybe c\n' +
+                   '                        ^^^^^^^^\n' +
                    '                           1\n' +
                    '\n' +
                    '1)  [1, 2, 3] :: Array Number, Array FiniteNumber, Array NonZeroFiniteNumber, Array Integer, Array ValidNumber\n' +
                    '\n' +
-                   'The value at position 1 is not a member of ‘TypeRep’.\n'));
+                   'The value at position 1 is not a member of ‘Function’.\n'));
 
-    throws(function() { S.gets(Number, null); },
+    throws(function() { S.gets(T, null); },
            errorEq(TypeError,
                    'Invalid value\n' +
                    '\n' +
-                   'gets :: Accessible a => TypeRep -> Array String -> a -> Maybe b\n' +
-                   '                                   ^^^^^^^^^^^^\n' +
-                   '                                        1\n' +
+                   'gets :: Accessible a => Function -> Array String -> a -> Maybe c\n' +
+                   '                                    ^^^^^^^^^^^^\n' +
+                   '                                         1\n' +
                    '\n' +
                    '1)  null :: Null\n' +
                    '\n' +
                    'The value at position 1 is not a member of ‘Array String’.\n'));
 
-    throws(function() { S.gets(Number, [], null); },
+    throws(function() { S.gets(T, [], null); },
            errorEq(TypeError,
                    'Type-class constraint violation\n' +
                    '\n' +
-                   'gets :: Accessible a => TypeRep -> Array String -> a -> Maybe b\n' +
-                   '        ^^^^^^^^^^^^                               ^\n' +
-                   '                                                   1\n' +
+                   'gets :: Accessible a => Function -> Array String -> a -> Maybe c\n' +
+                   '        ^^^^^^^^^^^^                                ^\n' +
+                   '                                                    1\n' +
                    '\n' +
                    '1)  null :: Null\n' +
                    '\n' +
                    '‘gets’ requires ‘a’ to satisfy the Accessible type-class constraint; the value at position 1 does not.\n'));
   });
 
-  it('returns a Maybe', function() {
-    var obj = {x: {z: 0}, y: 42};
-    eq(S.gets(Number, ['x'], obj), S.Nothing());
-    eq(S.gets(Number, ['y'], obj), S.Just(42));
-    eq(S.gets(Number, ['z'], obj), S.Nothing());
-    eq(S.gets(Number, ['x', 'z'], obj), S.Just(0));
-    eq(S.gets(Number, ['a', 'b', 'c'], obj), S.Nothing());
-    eq(S.gets(Number, [], obj), S.Nothing());
-    eq(S.gets(Object, [], obj), S.Just({x: {z: 0}, y: 42}));
+  it('returns Nothing if the predicate returns false', function() {
+    eq(S.gets(F, [], {}), S.Nothing());
+    eq(S.gets(F, ['x'], {x: 1}), S.Nothing());
+  });
+
+  it('returns Just if the predicate returns true', function() {
+    eq(S.gets(T, [], {}), S.Just({}));
+    eq(S.gets(T, ['x'], {x: 1}), S.Just(1));
   });
 
-  it('does not rely on constructor identity', function() {
-    eq(S.gets(RegExp, ['x'], {x: vm.runInNewContext('/.*/')}), S.Just(/.*/));
-    eq(S.gets(vm.runInNewContext('RegExp'), ['x'], {x: /.*/}), S.Just(/.*/));
+  it('returns a Maybe', function() {
+    var obj = {x: {z: 0}, y: 42};
+    eq(S.gets(S.is(Number), ['x'], obj), S.Nothing());
+    eq(S.gets(S.is(Number), ['y'], obj), S.Just(42));
+    eq(S.gets(S.is(Number), ['z'], obj), S.Nothing());
+    eq(S.gets(S.is(Number), ['x', 'z'], obj), S.Just(0));
+    eq(S.gets(S.is(Number), ['a', 'b', 'c'], obj), S.Nothing());
+    eq(S.gets(S.is(Number), [], obj), S.Nothing());
+    eq(S.gets(S.is(Object), [], obj), S.Just({x: {z: 0}, y: 42}));
   });
 
   it('is curried', function() {
-    eq(S.gets(Number).length, 2);
-    eq(S.gets(Number)(['x']).length, 1);
-    eq(S.gets(Number)(['x'])({x: 42}), S.Just(42));
+    eq(S.gets(T).length, 2);
+    eq(S.gets(T)(['x']).length, 1);
+    eq(S.gets(T)(['x'])({x: 42}), S.Just(42));
   });
 
 });