Add HISTORY file.

HISTORY.md

@@ -0,0 +1,79 @@
+History of Castile
+==================
+
+Castile 0.5
+-----------
+
+### Distribution
+
+*   Added HISTORY.md file.
+
+### Language
+
+*   Scoped structs can be declared with the `for (...)` clause
+    after the struct.  A value of a scope struct can only be
+    `make`d, and the fields of such a value can only be accessed,
+    lexically inside one of the definitions named in the `for`.
+*   Nested structs can be tested for deep equality.
+*   Values of union type can be tested for equality.
+
+### Implementation
+
+*   Requesting the AST be dumped, will also dump the AST with
+    type assignments, if an error occurs during type checking.
+
+Castile 0.4
+-----------
+
+### Distribution
+
+*   Re-focused project: Castile is a simple imperative language
+    with union types.
+*   Released under a 3-clause BSD license.
+
+### Language
+
+*   `struct`s cannot be compared for order, it is a static error.
+*   A union type is allowed to be promoted to a bigger union type,
+    or to itself.
+
+### Implementation
+
+*   Completed the C-generating backend of the compiler: it passes all tests now.
+*   Implemented `str` builtin, equality testing of `struct`s in all backends.
+*   Improved pretty-printing of code in C and Ruby backends.
+*   Implemented `ne` in stackmac implementation.
+
+Castile 0.3 revision 2021.0625
+------------------------------
+
+*   Updated implementation to run under both Python 2 and Python 3.
+*   Refactored test suite, making it more idiomatic Falderal.
+
+Castile 0.3 revision 2016.0331
+------------------------------
+
+*   Fixed generated Ruby code that worked in Ruby 1.8 but fails in Ruby 1.9.
+
+Castile 0.3 revision 2015.0101
+------------------------------
+
+*   Stopped using deprecated Falderal variable names in test suite.
+
+Castile 0.3
+-----------
+
+*   Treatment of local variables became more Python-like.
+*   Beginnings of a C backend in compiler.
+
+Castile 0.2
+-----------
+
+*   Heavy development of the language, with many changes.
+*   Added JavaScript, Ruby, and stackmac (stack-machine) backends to compiler.
+
+Castile 0.1
+-----------
+
+Initial release of Castile, an unremarkable language with an unremarkable
+compiler/interpreter in Python.