New features

Added support for indexing on the left-hand sides of declarations, record field constructors, and record updaters (issue #577). This builds on a new prelude function called generate, where the new syntax x @ i = e is sugar for x = generate (\i -> e).
Added support for element type ascriptions on sequence enumerations. The syntax [a,b..c:t] indicates that the elements should be of type t.
Added support for wildcards in sequence enumerations. For example, the syntax [1 .. _] : [3][8] yields [0x01, 0x02, 0x03]. It can also be used polymorphically. For example, the most general type of [1 .. _] is {n, a} (n >= 1, Literal n a, fin n) => [n]a
Changed the syntax of type signatures to allow multiple constraint arrows in type schemas (issue #599). The following are now equivalent:
```
  f : {a} (fin a, a >= 1) => [a] -> [a]

  f : {a} (fin a) => (a >= 1) => [a] -> [a]
```
Added a mechanism for user-defined type constraint operators, and use this to define the new type constraint synonyms (<) and (>) (issues #400, #618).
Added support for primitive type declarations. The prelude now uses this mechanism to declare all of the basic types.
Added support for Haskell-style "block arguments", reducing the need for parentheses in some cases. For example, generate (\i -> i +1) can now be written generate \i -> i + 1.
Improved shadowing errors (part of the fix for issue #569).

Bug fixes