; new_eps_fam_insts <- mapM tcIfaceFamInst (mi_fam_insts iface)
; new_eps_rules <- tcIfaceRules ignore_prags (mi_rules iface)
- ; let { final_iface = iface { mi_decls = panic "No mi_decls in PIT",
- mi_insts = panic "No mi_insts in PIT",
- mi_rules = panic "No mi_rules in PIT" } }
+ ; let { final_iface = iface {
+ mi_decls = panic "No mi_decls in PIT",
+ mi_insts = panic "No mi_insts in PIT",
+ mi_fam_insts = panic "No mi_fam_insts in PIT",
+ mi_rules = panic "No mi_rules in PIT"
+ } }
; updateEps_ $ \ eps ->
eps {
new_eps_insts,
eps_fam_inst_env = extendFamInstEnvList (eps_fam_inst_env eps)
new_eps_fam_insts,
+ eps_mod_fam_inst_env
+ = let
+ fam_inst_env =
+ extendFamInstEnvList emptyFamInstEnv
+ new_eps_fam_insts
+ in
+ extendModuleEnv (eps_mod_fam_inst_env eps)
+ mod
+ fam_inst_env,
eps_stats = addEpsInStats (eps_stats eps)
(length new_eps_decls)
(length new_eps_insts) (length new_eps_rules) }
; thing <- forkM doc $ do { bumpDeclStats main_name
; tcIfaceDecl ignore_prags decl }
- -- Populate the type environment with the implicitTyThings too
+ -- Populate the type environment with the implicitTyThings too.
+ --
+ -- Note [Tricky iface loop]
+ -- ~~~~~~~~~~~~~~~~~~~~~~~~
+ -- The delicate point here is that 'mini-env' should be
+ -- buildable from 'thing' without demanding any of the things 'forkM'd
+ -- by tcIfaceDecl. For example
+ -- class C a where { data T a; op :: T a -> Int }
+ -- We return the bindings
+ -- [("C", <cls>), ("T", lookup env "T"), ("op", lookup env "op")]
+ -- The call (lookup env "T") must return the tycon T without first demanding
+ -- op; because getting the latter will look up T, hence loop.
+ --
+ -- Of course, there is no reason in principle why (lookup env "T") should demand
+ -- anything do to with op, but take care:
+ -- (a) implicitTyThings, and
+ -- (b) getOccName of all the things returned by implicitThings,
+ -- must not depend on any of the nested type-checks
+ --
+ -- All a bit too finely-balanced for my liking.
+
; let mini_env = mkOccEnv [(getOccName t, t) | t <- implicitTyThings thing]
lookup n = case lookupOccEnv mini_env (getOccName n) of
Just thing -> thing
eps_fam_inst_env = emptyFamInstEnv,
eps_rule_base = mkRuleBase builtinRules,
-- Initialise the EPS rule pool with the built-in rules
+ eps_mod_fam_inst_env
+ = emptyModuleEnv,
eps_stats = EpsStats { n_ifaces_in = 0, n_decls_in = 0, n_decls_out = 0
, n_insts_in = 0, n_insts_out = 0
, n_rules_in = length builtinRules, n_rules_out = 0 }
hsep [ int (n_rules_out stats), text "rule decls imported, out of",
int (n_rules_in stats), text "read"]
]
-\end{code}
+\end{code}
%************************************************************************
, pprFixities (mi_fixities iface)
, vcat (map pprIfaceDecl (mi_decls iface))
, vcat (map ppr (mi_insts iface))
+ , vcat (map ppr (mi_fam_insts iface))
, vcat (map ppr (mi_rules iface))
, pprDeprecs (mi_deprecs iface)
]