Copilot.Language.Operators.Local

Let expressions.

Although Copilot is a DSL embedded in Haskell and Haskell does support let expressions, we want Copilot to be able to implement sharing, to detect when the same stream is being used in multiple places in a specification and avoid recomputing it unnecessarily.

Documentation

local :: (Typed a, Typed b) => Stream a -> (Stream a -> Stream b) -> Stream b

Let expressions.

Create a stream that results from applying a stream to a function on streams. Standard usage would be similar to Haskell's let. See the following example, where stream1, stream2 and s are all streams carrying values of some numeric type:

  expression = local (stream1 + stream2) $ \s ->
               (s >= 0 && s <= 10)