Calculator demo fails to compile about agda-frp-js HOT 4 OPEN

Interestingly, the demos do compile if I change the implementation of view to...

view : ∀ {w} → ⟦ Beh (DOM w) ⟧
view {t = _} with keypad
... | (dom , evt) = display (model evt) ++ dom

... i.e., I match on the time argument explicitly, so I don't think the problem is with your implementation. This is odd behaviour nonetheless. Let me know what your thoughts on this are.

from agda-frp-js.

Agda does not eagerly introduce hidden arguments on the lhs any more, if I am not mistaken. This explains the change of behavior.

from agda-frp-js.

Hmm, this behaviour seems to be caused by the use of a with-clause.
Replacing the with by an explicit function causes the code to compile:

view : ∀ {w} → ⟦ Beh (DOM w) ⟧
view {w} = f keypad where

f : ⟦ _ ∧ _ ⇒ Beh (DOM w) ⟧
f (dom , evt) = display (model evt) ++ dom

I'm not sure what to do about this, as the eager binding of time
arguments is rather hard-wired into the FRP model. We could just
explicitly bind {t} in the definition of view, but that's rather
breaking the FRP abstraction.

A.

On 02/17/2014 02:53 AM, Andreas Abel wrote:

Agda does not eagerly introduce hidden arguments on the lhs any more, if
I am not mistaken. This explains the change of behavior.

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#4 (comment).

from agda-frp-js.

It works also without introducing the hidden argument explicitely.

view : ∀ {w} → ⟦ Beh (DOM w) ⟧
view = vw keypad
  where vw : ⟦ _ ∧ _ ⇒ Beh (DOM _) ⟧
        vw (dom , evt) = display (model evt) ++ dom

Currently, hidden arguments are eagerly introduced to check the where clauses, but not any with-generated functions. Maybe you should file an Agda issue.

from agda-frp-js.