gdp's Comments

larrλtheliquid -> Lemma the Ultimate : Intro to Proofs-as-Programs

Sun, 25 Oct 2009 18:58:48 +0000

Ah yes, that makes sense. Thank you for investigating and clarifying that. +1

larrλtheliquid -> Lemma the Ultimate : Intro to Proofs-as-Programs

Sun, 25 Oct 2009 18:31:45 +0000

Agda tracks the dependencies between all function parameters and the recursive calls in the body, and if the resulting dependencies are of decreasing order then the function will terminate. It should be noted though that the termination checker can find false positives, in which case you must fiddle with moving things around a bit to get the termination to check.

larrλtheliquid -> Lemma the Ultimate : Intro to Proofs-as-Programs

Sun, 25 Oct 2009 15:58:47 +0000

You're right that I did not cover Agda's requirement of termination checking. More specifically, the rule is that recursive calls must use inputs that are structurally smaller than the inputs of the original function. However, this requirement is not present in all proof languages. In Guru you can still prove things such as the reflexive property even about functions that never terminate (see page 28 of the Guru book). Additionally, once totality has been proven, you can register the function as total which gives you access to more things you can prove about it and with it that are restricted by default (page 50).

larrλtheliquid -> Lemma the Ultimate : Intro to Proofs-as-Programs

Sun, 25 Oct 2009 15:46:42 +0000

Woops, fixed that, thanks =)

larrλtheliquid -> Lemma the Ultimate : Roadmap

Wed, 14 Oct 2009 19:21:35 +0000

Thanks for the clarifications, greatly appreciated!

Union Station : Cucumber: Step Argument Transforms

Wed, 23 Sep 2009 05:12:49 +0000

Cucumber might not have your situation built in, but Transform's are very flexible! I think I understand what you need better now, check out this implementation of your TokenTransform: http://gist.github.com/191691

Union Station : Cucumber: Step Argument Transforms

Tue, 22 Sep 2009 15:31:14 +0000

Yup, the Transform regex just has to match a capture group, not have identical text. That means groups in step defs that don't match anything get checked against every Transform, and a group that matches short circuits checking the rest.

Union Station : Cucumber: Step Argument Transforms

Tue, 22 Sep 2009 05:00:36 +0000

Heya Eric, I'm not sure if I understand your situation exactly, let me know if this solves it: # support file Transform /^new young child (\\w+)$ do |first_name| Person.gen(:child, :first_name => first_name) end Transform /^new guest user (\\w+)$/ do |username| User.gen(:guest, :username => username) end Transform /^person (\\w+)$/ do |first_name| Person.first :first_name => first_name end Transform /^user (\\w+)$/ do |username| User.first :username => username end # step definition file Given /^a (\\w+) added by (\\w+)$/ do | person, user | user.add person end Then /^(user \\w+) has a referral for (person \\w+)$/ do |user, person | user.should have_referral_for(person) end # feature file Given a new young child Mike added by new guest user coolio Then user coolio has a referral for person Mike

Union Station : Cucumber: Step Argument Transforms

Thu, 17 Sep 2009 04:43:43 +0000

If a transform fails then all the others defined before it (from newest to oldest) are tried. If no transform ends up matching then the original argument is returned.

Union Station : Cucumber: Step Argument Transforms

Tue, 15 Sep 2009 16:41:07 +0000

For simple cases where you do need to parse the entire step argument, you can include capture groups that get yielded as arguments instead: Transform /^age (\\d+)$/ do |age_string| age_string.to_i end Transform /^user (\\w+)$/ do |username| User.first :username => username end Also, as of Cucumber 0.3.101 step argument transforms are in the official release!

Union Station : Cucumber: Step Argument Transforms

Mon, 14 Sep 2009 23:58:34 +0000

Hi JJM, If what you suggested were possible, then you would still not keep code DRY because you would need to duplicate the various #to_whatever calls in each step definition. In Ruby, you can extend the String class to add extra #to_whatever methods like you suggested, but you can't make method calls inside the block parameters like you showed.