[clean-list] question about implicit imports of definition

[Arjen van Weelden]

Jigang Sun wrote:
> I am studying Clean module system.  What I know is that function definition can be pass-through (downwards) via definition module by importing. For example,
> 
> definition module aa
> import StdEnv
> 
> implementation module aa
> //empty body 
> 
> //Start module
> module try
> import aa
> 
> Start = (+) 1 2
> 
> works OK.
> 
> But I found imported definitions could not be passed horizontally to corresponding implementation module as showed by the following example. StdEnv is imported in definition module aa, in implementation module aa I turned off "import StdEnv", then "Error [aa.icl,4,]: + undefined" error message is given.
> 
> definition module aa
> import StdEnv
> add2 :: Int Int -> Int
> 
> implementation module aa
> //import StdEnv
> add2 ::Int Int -> Int
> add2 x y = x+y //line 4, + is considered undefined
> 
> 
> module try  //Start module
> import aa
> 
> Start = add2 1 2
> 
> I wonder if definitions imported into a definition module should be available to its corresponding implemtation module?
> 
> Thanks.
> Jigang
> 
The current Clean compiler does not automatically include imports from a 
definition module into an implementation module. You are observing 
correct behavior.

You are not the only one who finds this counter-intuitive, confusing, 
and/or inconvenient. IIRC, one can construct examples where this is 
useful, but these tend to be extreme cases IMHO. The current behavior is 
a bit like C, and maybe we should expect a little more from a 
higher-level language. :-)

kind regards,
	Arjen