[Haskell-cafe] Suggestions for #defines with FFI

[Donn Cave]

On Wed, 27 Jul 2005, John Goerzen wrote:
...
> Right now, I'm using hsc2hs, and writing something like this:
> 
> #enum LDAPInt, , LDAP_PORT, LDAPS_PORT, LDAP_API_VERSION, LDAP_VENDOR_NAME, \
>       LDAP_OPT_API_INFO, LDAP_OPT_DESC, LDAP_OPT_DEREF, \
>       LDAP_OPT_SIZELIMIT, LDAP_OPT_TIMELIMIT, LDAP_OPT_REFERRALS, \
>       LDAP_OPT_RESTART, LDAP_OPT_PROTOCOL_VERSION, LDAP_OPT_SERVER_CONTROLS, \
> 
> That boils down to this:
> 
> ldapPort :: LDAPInt
> ldapPort =  389
> ldapsPort :: LDAPInt
> ldapsPort =  636
> 
> So I still lack typechecking, and have to manually key in all the
> identifiers, but at least the system pulls their values and types in for
> me.

I wanted them to be enumerated types in Haskell where appropriate,
and the only thing I could think of was

  data LDAPOpt = LDAP_OPT_X_TLS
        | LDAP_OPT_X_TLS_REQUIRE_CERT
        | LDAP_OPT_PROTOCOL_VERSION
        | LDAP_OPT_DEBUG_LEVEL
  fromLDAPOpt LDAP_OPT_X_TLS = (#const LDAP_OPT_X_TLS)
  fromLDAPOpt LDAP_OPT_X_TLS_REQUIRE_CERT = (#const LDAP_OPT_X_TLS_REQUIRE_CERT)
  fromLDAPOpt LDAP_OPT_PROTOCOL_VERSION = (#const LDAP_OPT_PROTOCOL_VERSION)
  fromLDAPOpt LDAP_OPT_DEBUG_LEVEL = (#const LDAP_OPT_DEBUG_LEVEL)

etc.

	Donn Cave, donn at drizzle.com