bug#54752: import: hackage: `elif` conditionals not supported

[Lars-Dominik Braun]

Hi Philip,

thank you!

> Unfortunately, building raaz still fails (first because of the description, 
> then because some internal libraries are added as external dependencies, and 
> then for... other reasons I haven't figured out. But all of those are 
> separate issues.

You’re right, it fails with this error for me, which indicates 
haskell-build-system has a bug _somewhere_.

---snip---
starting phase `register'
running "runhaskell Setup.hs" with command "register" and parameters 
("--gen-pkg-config=/gnu/store/8m0w1688syvcmhjr2ym1max430jmwjag-ghc-raaz-0.3.6/ghc-raaz-0.3.6.conf")
error: in phase 'register': uncaught exception:
system-error "fport_read" "~A" ("Is a directory") (21)
phase `register' failed after 6.9 seconds
Backtrace:
          11 (primitive-load "/gnu/store/jpf2lwn33nq08nkqrkr5q232c51…")
In guix/build/gnu-build-system.scm:
    906:2 10 (gnu-build #:source _ #:outputs _ #:inputs _ #:phases . #)
In ice-9/boot-9.scm:
  1752:10  9 (with-exception-handler _ _ #:unwind? _ # _)
In srfi/srfi-1.scm:
    634:9  8 (for-each #<procedure 7ffff2048e20 at guix/build/gnu-b…> …)
In ice-9/boot-9.scm:
  1752:10  7 (with-exception-handler _ _ #:unwind? _ # _)
In guix/build/gnu-build-system.scm:
   927:23  6 (_)
In guix/build/haskell-build-system.scm:
   244:23  5 (register #:name _ #:system _ #:inputs _ #:outputs _)
In ice-9/ports.scm:
   433:17  4 (call-with-input-file _ _ #:binary _ #:encoding _ # _)
In ice-9/rdelim.scm:
   160:18  3 (read-string _)
In unknown file:
           2 (read-char #<input: /gnu/store/8m0w1688syvcmhjr2ym1max4…>)
In ice-9/boot-9.scm:
  1685:16  1 (raise-exception _ #:continuable? _)
  1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
In procedure fport_read: Is a directory
---snap---

Cheers,
Lars