|
|
|
|
|
|
by clarus
3622 days ago
|
|
|
> whereas reasoning about equivalence of JavaScript programs requires carrying out the entire reasoning process in a separate metalanguage I do not see how you can reason about Haskell in Haskell either, as this is a programming language and not a proof language (maybe I am missing something?). > Haskell doesn't have a propositional equality type constructor. This is what I meant. Since with both Haskell and JavaScript you will need to define a propositional equality, in my experience this does not help that much to have a better decidable equality. |
|
|
http://www.haskellforall.com/2013/12/equational-reasoning.ht...
http://www.haskellforall.com/2014/07/equational-reasoning-at...
The reasoning is entirely carried out by replacing Haskell expressions with contextually equivalent ones.
> Since with both Haskell and JavaScript you will need to define a propositional equality
No, you need much more than a propositional equality to be able to reason about JavaScript programs. If you try to use Haskell-style equational reasoning on JavaScript objects, you can only pick between your reasoning being trivial (because every object reference is only equal to references to physically the same object) or unsound! So if you want a more useful notion of program equivalence, you'll have to use a separate logic (e.g. Hoare logic) or axiomatic system (e.g. Dijkstra's predicate transformer semantics) for reasoning about imperative programs.