[ANN] core.typed 0.3.31 - "paired" rest arguments like hash-map/assoc

[Ambrose Bonnaire-Sergeant]

Hi,

Very excited to *finally* merge Di Xu's GSoC 2014 work. This is awesome stuff!

We can now type check usages of hash-map/assoc/apply in much finer detail.

[org.clojure/core.typed "0.3.31"]

core.typed can now support different patterns of "rest" arguments -- think `hash-map`

and `assoc`.

There are two new kinds of rest arguments.

1. prest arguments, denoted by. Like *, but written <*

2. pdot arguments, denoted by. Like ... but written <...

Think of <* as "splicing *" and <... as "splicing ...".

eg. Here's the new type of hash-map:

clojure.core/hash-map (All [x y] [(HSequential [x y] :repeat true) <* -> (Map x y)])

It uses <* to enforce paired arguments. It is now a static type error to provide an

odd number of arguments to hash-map.

The :repeat argument to HSequential repeats the fixed members

an infinite number of times. The type (HSequential [x y] :repeat true)

is the type of all heterogeneous sequences with even counts.

The <* "splices" this into the function parameter list. Now 

(HSequential [x y] :repeat true) <*

means any even number of arguments are allowed.

"apply" and "assoc" also have similar updated types, using <...

Please try out these functions and report if checking them is more useful.

This is only the tip of the iceberg of what Di has implemented --- please respond

if more detail/clarifications are needed.

Thanks!

Ambrose