record punning

[leque]

I would like to be able to use so-called record punning found in Successor ML, OCaml, ECMAScript (Shorthand property names), ..., etc. also in SATySFi.

With this feature, we can construct a record

let f x y = (| x; y |)

instead of

let f x y = (| x = x; y = y |)

This can also be applied to record patterns (#358), so we can write

let f (| x; y |) = (x, y)

instead of

let f (| x = x; y = y |) = (x, y)