Multiple input files and -o clobbers the output

[kfish]

I would like to structure my Haskell code in separate files (one file per module, as Haskell requires), but generate one output javascript file.

Currently, if I use a commandline like:

fay --package fay-text -o output.js Foo.hs Bar.hs

then fay will:

1. compile Foo.hs, writing the result to output.js
2. compile Bar.hs, overwriting output.js

So -o cannot be used with multiple files.

If I instead use multiple invocations:

fay --package fay-text Foo.hs
fay --package fay-text Bar.hs

then the resulting Foo.js and Bar.js will contain redundant copies of the same code (RTS, stdlib and fay-text library code). If I build with --no-stdlib --library, then I still get redundant copies of fay-text.

[bergmark]

One simple (and perhaps better?) solution for this is to have a top level module that imports both Foo and Bar.

[kfish]

Ah! I can make a toplevel module Main.hs that does nothing but import:

module Main where

import Foo
import Bar

and build it with:

fay --package fay-text Main.hs

it does the right thing, without any interference between Foo and Bar. When generating modules to call from javascript, I can do:

fay --package fay-text Main.hs --strict Foo,Bar

which will create Main.js, defining Strict.Foo and Strict.Bar. That worksforme.

(We could probably fiddle it so that giving multiple arguments is equivalent to compiling such an import-only module)

[bergmark]

Also related to #330 by the way.

Some possible solutions:

• If we add such a dummy module --library would be implicit for multiple inputs
• Add the dummy module and produce a main call for each input file.
• Do separate compilation runs for each module, but keep the compile state so no duplicated output is produced.
• Only compile the module named Main, but add the other module to the possible includes. This is how GHC does it, so it sounds like the best solution to me.

I'll reopen this, the current behavior is unintuitive/broken.

[bergmark]

Spring cleaning. Lack of activity, it's unlikely that this will happen. Use a top level module.