[Agda] .agdai weirdness

[Conor McBride]

Hi folks

First, thanks for the aquamacs tips. Whatever it was,
it's now in colour and going well. (Peculiarly, before
I copied .emacs stuff from Ulf, I had *one* file
which suddenly started appearing in colour for no
obvious reason, when the rest stayed stubbornly
monochrome. Hmm.)

So yes, I've been messing about with enough stuff to
need more than one file. And I've hit a distinctly
bizarre happening. Maybe I'm not using modules in the
right way, but I don't think it's falling over as
gracefully as it might. I know these things take time,
and I expect I can work around the issue.

Er, um, I'm afraid I've (tried and) failed to condense
the problem to a toy example, so I'll summarize. If
you want a tar of the files, just ask.

Here goes. I developed a library of stuff in short
files, not entirely linearly. I wanted to build a
wrapper so I could import in one go.

{--- begin Syntacticosmos.agda ----------------------}
module Syntacticosmos (Gnd : Set)(U : Set)(El : U -> Set) where

open import Basics
open import Pr
open import Nom
import Kind
open module KindGUEl = Kind Gnd U El public
import Cxt
open module CxtK = Cxt Kind public
import Loc
open module LocK = Loc Kind public
import Term
open module TermGUEl = Term Gnd U El public
import Shift
open module ShiftGUEl = Shift Gnd U El public
import Eta
open module EtaGUEl = Eta Gnd U El public
import Inst
open module InstGUEl = Inst Gnd U El public
import Subst
open module SubstGUEl = Subst Gnd U El public
{--- end Syntacticosmos.agda ----------------------}

The file loads fine. So far so good. Then I tried to
use it...

{--- begin UntypedLambda.agda -----------------------}
module UntypedLambda where

open import Basics
open import Pr
open import Nom
import Syntacticosmos

data Tag : Set where
   lamT : Tag
   appT : Tag

open module ULam = Syntacticosmos TT TT (\_ -> Tag)

LAM : Kind
LAM = Ty _

SigLAM : Kind
SigLAM = Pi _ conk where
   conk : Tag -> Kind
   conk lamT = (LAM |> LAM) |> LAM
   conk appT = LAM |> LAM |> LAM

Lam : Cxt -> Set
Lam G = G [! SigLAM !]- LAM

lam : {G : Cxt}(x : Nom){Gx : [| G Hasn't x |]} ->
       Lam ((G [ x - LAM ]) {Gx}) -> Lam G
lam x {Gx} b = G[ lamT G^ G\\ (bind x {Gx} b) G& Gnil ]

app : {G : Cxt} -> Lam G -> Lam G -> Lam G
app f s = G[ appT G^ f G& s G& Gnil ]

moo : Lam EC
moo = lam Ze (lam (Su Ze) (var Ze))

noo : Lam EC
noo = lam (Su Ze) (lam Ze (var (Su Ze)))

coo : Id moo noo
coo = refl
{--- end UntypedLambda.agda ----------------------------}

When I try to load UntypedLambda.agda, it fails at
import Syntacticosmos with the following error:

   /Users/ctm/Desktop/Syntacticosmos/UntypedLambda.agda:6,1-22
   /Users/ctm/Desktop/Syntacticosmos/Syntacticosmos.agdai:
   getModificationTime: does not exist (No such file or directory)

Moreover, by the joy of Finder, I watched the directory
as this ran. The file Syntacticosmos.agdai appeared and
then disappeared in the course of the failed load.
My attempts to mimic the pattern of files with similar
structure but less distraction have not reproduced the
problem. I hope you enjoy the distraction...

Does this ring any bells with any one? How should I be
organizing the library modules, anyway?

I'm sorry it's all a bit sick. On the upside, I'm really
pleased at the way the engines are taking what I'm
throwing at them (a universe of globally named, locally
nameless syntaxes with binding). I probably shouldn't
be allowed this much fun, but it's the weekend and I'm
not so well at the moment, hence hacking therapy.

Anyhow, I thought I'd share this peculiar happening.
I don't even know how to begin speculating about the
problem.

All the best

Conor