Comments on: Deriving list scans

By: Zemyla

Zemyla — Thu, 14 May 2015 05:28:11 +0000

A left scan is just a traversal over the state monad, and a right scan is just a traversal over the state monad with the Backwards combinator. That should get you the most general scanning.

By: Conal Elliott » Blog Archive » Composable parallel scanning

Conal Elliott » Blog Archive » Composable parallel scanning — Tue, 01 Mar 2011 22:34:00 +0000

[...] post Deriving list scans gave a simple specification of the list-scanning functions scanl and scanr, and then transformed [...]

By: Conal Elliott » Blog Archive » Deriving parallel tree scans

Conal Elliott » Blog Archive » Deriving parallel tree scans — Tue, 01 Mar 2011 20:41:29 +0000

[...] About « Deriving list scans [...]

By: conal

conal — Sun, 27 Feb 2011 17:24:04 +0000

Hey, Jake. Developing the sort of environment you're suggesting was the thrust of the research group I was part of in grad school (summarized here). There was a lot of activity at the time, I think largely spurred by the work of Burstall & Darlington. I don't know what happened to the dream of mechanically assisted program derivation.

By: Jake McArthur

Jake McArthur — Sat, 26 Feb 2011 17:40:39 +0000

I don't have much experience with program derivation, but as I've told you before, I think it's really cool! It occurred to me about a week ago, I think, that it would be cool to have an interactive environment to experiment with semantics preserving code transformations like this. Do you happen to know of any existing environments like that? I am, of course, aware of theorem provers and such, but all a theorem prover can do is check a manually written proof that two versions of a function are equivalent, whereas what I think would be neat is an environment to help you explore the space of equivalent functions by presenting semantics preserving transformations to you and allowing you to choose which ones to apply as you go.