Meta issue for syntax improvements in Pulse

- [x] `fn (p:int -> int) ...` doesn't parse, it has to be written as `fn (p:(int -> int)) ...` (note the extra parenthesis around the arrow)
- [x] `let _ : t = e;` doesn't parse, it has to be written as `let _u : t = e`
- [x] refinement types annotation `x:int { p x }` doesn't work, it has to be written as `x:(x:int { p x })`

Issue #269 lists three Pulse syntax cases, all marked complete: function arrow types, wildcard let bindings, and refinement type annotations. Start by checking whether the meta issue has any remaining unchecked syntax cases; done means the issue records the remaining cases and their expected syntax.

Written by the indexing model from the issue text.