diff --git a/src/environments.js b/src/environments.js
index ff294ca7a..c323d433e 100644
--- a/src/environments.js
+++ b/src/environments.js
@@ -38,141 +38,141 @@ function parseArray(parser, pos, mode, result) {
 }
 
 /*
- * An environment definition is very similar to a function definition.
- * Each element of the following array may contain
- *  - names: The names associated with a function. This can be used to
- *           share one implementation between several similar environments.
+ * An environment definition is very similar to a function definition:
+ * it is declared with a name or a list of names, a set of properties
+ * and a handler containing the actual implementation.
+ *
+ * The properties include:
  *  - numArgs: The number of arguments after the \begin{name} function.
  *  - argTypes: (optional) Just like for a function
  *  - allowedInText: (optional) Whether or not the environment is allowed inside
  *                   text mode (default false) (not enforced yet)
  *  - numOptionalArgs: (optional) Just like for a function
- *  - handler: The function that is called to handle this environment.
- *             It will receive the following arguments:
- *             - pos: the current position of the parser.
- *             - mode: the current parsing mode.
- *             - envName: the name of the environment, one of the listed names.
- *             - [args]: the arguments passed to \begin.
- *             - positions: the positions associated with these arguments.
+ * A bare number instead of that object indicates the numArgs value.
+ *
+ * The handler function will receive the following arguments:
+ *  - pos: the current position of the parser.
+ *  - mode: the current parsing mode.
+ *  - envName: the name of the environment, one of the listed names.
+ *  - [args]: the arguments passed to \begin.
+ *  - positions: the positions associated with these arguments.
+ * The handler is called with `this` referring to the parser.
+ * It must return a ParseResult.
  */
 
-var environmentDefinitions = [
-
-    // Arrays are part of LaTeX, defined in lttab.dtx so its documentation
-    // is part of the source2e.pdf file of LaTeX2e source documentation.
-    {
-        names: ["array"],
-        numArgs: 1,
-        handler: function(pos, mode, envName, colalign, positions) {
-            var parser = this;
-            colalign = colalign.value.map ? colalign.value : [colalign];
-            var cols = colalign.map(function(node) {
-                var ca = node.value;
-                if ("lcr".indexOf(ca) !== -1) {
-                    return {
-                        type: "align",
-                        align: ca
-                    };
-                } else if (ca === "|") {
-                    return {
-                        type: "separator",
-                        separator: "|"
-                    };
-                }
-                throw new ParseError(
-                    "Unknown column alignment: " + node.value,
-                    parser.lexer, positions[1]);
-            });
-            var res = {
-                type: "array",
-                cols: cols,
-                hskipBeforeAndAfter: true // \@preamble in lttab.dtx
-            };
-            res = parseArray(parser, pos, mode, res);
-            return res;
-        }
-    },
-
-    // The matrix environments of amsmath builds on the array environment
-    // of LaTeX, which is discussed above.
-    {
-        names: [
-            "matrix",
-            "pmatrix",
-            "bmatrix",
-            "Bmatrix",
-            "vmatrix",
-            "Vmatrix"
-        ],
-        handler: function(pos, mode, envName) {
-            var delimiters = {
-                "matrix": null,
-                "pmatrix": ["(", ")"],
-                "bmatrix": ["[", "]"],
-                "Bmatrix": ["\\{", "\\}"],
-                "vmatrix": ["|", "|"],
-                "Vmatrix": ["\\Vert", "\\Vert"]
-            }[envName];
-            var res = {
-                type: "array",
-                hskipBeforeAndAfter: false // \hskip -\arraycolsep in amsmath
-            };
-            res = parseArray(this, pos, mode, res);
-            if (delimiters) {
-                res.result = new ParseNode("leftright", {
-                    body: [res.result],
-                    left: delimiters[0],
-                    right: delimiters[1]
-                }, mode);
-            }
-            return res;
-        }
-    },
-
-    // A cases environment (in amsmath.sty) is almost equivalent to
-    // \def\arraystretch{1.2}%
-    // \left\{\begin{array}{@{}l@{\quad}l@{}} … \end{array}\right.
-    {
-        names: ["cases"],
-        handler: function(pos, mode, envName) {
-            var res = {
-                type: "array",
-                arraystretch: 1.2,
-                cols: [{
-                    type: "align",
-                    align: "l",
-                    pregap: 0,
-                    postgap: fontMetrics.metrics.quad
-                }, {
-                    type: "align",
-                    align: "l",
-                    pregap: 0,
-                    postgap: 0
-                }]
-            };
-            res = parseArray(this, pos, mode, res);
-            res.result = new ParseNode("leftright", {
-                body: [res.result],
-                left: "\\{",
-                right: "."
-            }, mode);
-            return res;
-        }
+function defineEnvironment(names, props, handler) {
+    if (typeof names === "string") {
+        names = [names];
     }
-];
-
-module.exports = (function() {
-    // nested function so we don't leak i and j into the module scope
-    var exports = {};
-    for (var i = 0; i < environmentDefinitions.length; ++i) {
-        var def = environmentDefinitions[i];
-        def.greediness = 1;
-        def.allowedInText = !!def.allowedInText;
-        def.numArgs = def.numArgs || 0;
-        def.numOptionalArgs = def.numOptionalArgs || 0;
-        for (var j = 0; j < def.names.length; ++j) {
-            exports[def.names[j]] = def;
-        }
+    if (typeof props === "number") {
+        props = { numArgs: props };
     }
-    return exports;
-})();
+    // Set default values of environments
+    var data = {
+        numArgs: props.numArgs || 0,
+        argTypes: props.argTypes,
+        greediness: 1,
+        allowedInText: !!props.allowedInText,
+        numOptionalArgs: props.numOptionalArgs || 0,
+        handler: handler
+    };
+    for (var i = 0; i < names.length; ++i) {
+        module.exports[names[i]] = data;
+    }
+}
+
+// Arrays are part of LaTeX, defined in lttab.dtx so its documentation
+// is part of the source2e.pdf file of LaTeX2e source documentation.
+defineEnvironment("array", {
+    numArgs: 1
+}, function(pos, mode, envName, colalign, positions) {
+    var parser = this;
+    colalign = colalign.value.map ? colalign.value : [colalign];
+    var cols = colalign.map(function(node) {
+        var ca = node.value;
+        if ("lcr".indexOf(ca) !== -1) {
+            return {
+                type: "align",
+                align: ca
+            };
+        } else if (ca === "|") {
+            return {
+                type: "separator",
+                separator: "|"
+            };
+        }
+        throw new ParseError(
+            "Unknown column alignment: " + node.value,
+            parser.lexer, positions[1]);
+    });
+    var res = {
+        type: "array",
+        cols: cols,
+        hskipBeforeAndAfter: true // \@preamble in lttab.dtx
+    };
+    res = parseArray(parser, pos, mode, res);
+    return res;
+});
+
+// The matrix environments of amsmath builds on the array environment
+// of LaTeX, which is discussed above.
+defineEnvironment([
+    "matrix",
+    "pmatrix",
+    "bmatrix",
+    "Bmatrix",
+    "vmatrix",
+    "Vmatrix"
+], {
+}, function(pos, mode, envName) {
+    var delimiters = {
+        "matrix": null,
+        "pmatrix": ["(", ")"],
+        "bmatrix": ["[", "]"],
+        "Bmatrix": ["\\{", "\\}"],
+        "vmatrix": ["|", "|"],
+        "Vmatrix": ["\\Vert", "\\Vert"]
+    }[envName];
+    var res = {
+        type: "array",
+        hskipBeforeAndAfter: false // \hskip -\arraycolsep in amsmath
+    };
+    res = parseArray(this, pos, mode, res);
+    if (delimiters) {
+        res.result = new ParseNode("leftright", {
+            body: [res.result],
+            left: delimiters[0],
+            right: delimiters[1]
+        }, mode);
+    }
+    return res;
+});
+
+// A cases environment (in amsmath.sty) is almost equivalent to
+// \def\arraystretch{1.2}%
+// \left\{\begin{array}{@{}l@{\quad}l@{}} … \end{array}\right.
+defineEnvironment("cases", {
+}, function(pos, mode, envName) {
+    var res = {
+        type: "array",
+        arraystretch: 1.2,
+        cols: [{
+            type: "align",
+            align: "l",
+            pregap: 0,
+            postgap: fontMetrics.metrics.quad
+        }, {
+            type: "align",
+            align: "l",
+            pregap: 0,
+            postgap: 0
+        }]
+    };
+    res = parseArray(this, pos, mode, res);
+    res.result = new ParseNode("leftright", {
+        body: [res.result],
+        left: "\\{",
+        right: "."
+    }, mode);
+    return res;
+});