2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[TcGenDeriv]{Generating derived instance declarations}
6 This module is nominally ``subordinate'' to @TcDeriv@, which is the
7 ``official'' interface to deriving-related things.
9 This is where we do all the grimy bindings' generation.
20 gen_tag_n_con_monobind,
22 con2tag_RDR, tag2con_RDR, maxtag_RDR,
27 #include "HsVersions.h"
29 import HsSyn ( InPat(..), HsExpr(..), MonoBinds(..),
30 Match(..), GRHSs(..), Stmt(..), HsLit(..),
31 HsBinds(..), StmtCtxt(..),
32 unguardedRHS, mkSimpleMatch
34 import RdrHsSyn ( RdrName(..), varUnqual, mkOpApp,
35 RdrNameMonoBinds, RdrNameHsExpr, RdrNamePat
37 import BasicTypes ( IfaceFlavour(..), RecFlag(..) )
38 import FieldLabel ( fieldLabelName )
39 import DataCon ( isNullaryDataCon, dataConTag,
40 dataConRawArgTys, fIRST_TAG,
43 import Name ( getOccString, getOccName, getSrcLoc, occNameString,
44 modAndOcc, OccName, Name )
46 import PrimOp ( PrimOp(..) )
47 import PrelInfo -- Lots of RdrNames
48 import SrcLoc ( mkGeneratedSrcLoc, SrcLoc )
49 import TyCon ( TyCon, isNewTyCon, tyConDataCons, isEnumerationTyCon,
52 import Type ( isUnLiftedType, isUnboxedType, Type )
53 import TysPrim ( charPrimTy, intPrimTy, wordPrimTy, addrPrimTy,
54 floatPrimTy, doublePrimTy
56 import Util ( mapAccumL, zipEqual, zipWithEqual,
57 zipWith3Equal, nOfThem )
58 import Panic ( panic, assertPanic )
59 import Maybes ( maybeToBool )
60 import List ( partition, intersperse )
63 %************************************************************************
65 \subsection{Generating code, by derivable class}
67 %************************************************************************
69 %************************************************************************
71 \subsubsection{Generating @Eq@ instance declarations}
73 %************************************************************************
75 Here are the heuristics for the code we generate for @Eq@:
78 Let's assume we have a data type with some (possibly zero) nullary
79 data constructors and some ordinary, non-nullary ones (the rest,
80 also possibly zero of them). Here's an example, with both \tr{N}ullary
81 and \tr{O}rdinary data cons.
83 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
87 For the ordinary constructors (if any), we emit clauses to do The
91 (==) (O1 a1 b1) (O1 a2 b2) = a1 == a2 && b1 == b2
92 (==) (O2 a1) (O2 a2) = a1 == a2
93 (==) (O3 a1 b1 c1) (O3 a2 b2 c2) = a1 == a2 && b1 == b2 && c1 == c2
96 Note: if we're comparing unboxed things, e.g., if \tr{a1} and
97 \tr{a2} are \tr{Float#}s, then we have to generate
99 case (a1 `eqFloat#` a2) of
102 for that particular test.
105 If there are any nullary constructors, we emit a catch-all clause of
109 (==) a b = case (con2tag_Foo a) of { a# ->
110 case (con2tag_Foo b) of { b# ->
111 case (a# ==# b#) of {
116 If there aren't any nullary constructors, we emit a simpler
123 For the @(/=)@ method, we normally just use the default method.
125 If the type is an enumeration type, we could/may/should? generate
126 special code that calls @con2tag_Foo@, much like for @(==)@ shown
130 We thought about doing this: If we're also deriving @Ord@ for this
133 instance ... Eq (Foo ...) where
134 (==) a b = case (compare a b) of { _LT -> False; _EQ -> True ; _GT -> False}
135 (/=) a b = case (compare a b) of { _LT -> True ; _EQ -> False; _GT -> True }
137 However, that requires that \tr{Ord <whatever>} was put in the context
138 for the instance decl, which it probably wasn't, so the decls
139 produced don't get through the typechecker.
143 deriveEq :: RdrName -- Class
144 -> RdrName -- Type constructor
145 -> [ (RdrName, [RdrType]) ] -- Constructors
146 -> (RdrContext, -- Context for the inst decl
147 [RdrBind], -- Binds in the inst decl
148 [RdrBind]) -- Extra value bindings outside
150 deriveEq clas tycon constrs
151 = (context, [eq_bind, ne_bind], [])
153 context = [(clas, [ty]) | (_, tys) <- constrs, ty <- tys]
156 (nullary_cons, non_nullary_cons) = partition is_nullary constrs
157 is_nullary (_, args) = null args
160 gen_Eq_binds :: TyCon -> RdrNameMonoBinds
164 tycon_loc = getSrcLoc tycon
165 (nullary_cons, nonnullary_cons)
166 | isNewTyCon tycon = ([], tyConDataCons tycon)
167 | otherwise = partition isNullaryDataCon (tyConDataCons tycon)
170 = if (null nullary_cons) then
171 case maybeTyConSingleCon tycon of
173 Nothing -> -- if cons don't match, then False
174 [([a_Pat, b_Pat], false_Expr)]
175 else -- calc. and compare the tags
177 untag_Expr tycon [(a_RDR,ah_RDR), (b_RDR,bh_RDR)]
178 (cmp_tags_Expr eqH_Int_RDR ah_RDR bh_RDR true_Expr false_Expr))]
180 mk_FunMonoBind tycon_loc eq_RDR ((map pats_etc nonnullary_cons) ++ rest)
182 mk_easy_FunMonoBind tycon_loc ne_RDR [a_Pat, b_Pat] [] (
183 HsApp (HsVar not_RDR) (HsPar (mk_easy_App eq_RDR [a_RDR, b_RDR])))
185 ------------------------------------------------------------------
188 con1_pat = ConPatIn data_con_RDR (map VarPatIn as_needed)
189 con2_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
191 data_con_RDR = qual_orig_name data_con
192 con_arity = length tys_needed
193 as_needed = take con_arity as_RDRs
194 bs_needed = take con_arity bs_RDRs
195 tys_needed = dataConRawArgTys data_con
197 ([con1_pat, con2_pat], nested_eq_expr tys_needed as_needed bs_needed)
199 nested_eq_expr [] [] [] = true_Expr
200 nested_eq_expr tys as bs
201 = foldl1 and_Expr (zipWith3Equal "nested_eq" nested_eq tys as bs)
203 nested_eq ty a b = HsPar (eq_Expr ty (HsVar a) (HsVar b))
206 %************************************************************************
208 \subsubsection{Generating @Ord@ instance declarations}
210 %************************************************************************
212 For a derived @Ord@, we concentrate our attentions on @compare@
214 compare :: a -> a -> Ordering
215 data Ordering = LT | EQ | GT deriving ()
218 We will use the same example data type as above:
220 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
225 We do all the other @Ord@ methods with calls to @compare@:
227 instance ... (Ord <wurble> <wurble>) where
228 a < b = case (compare a b) of { LT -> True; EQ -> False; GT -> False }
229 a <= b = case (compare a b) of { LT -> True; EQ -> True; GT -> False }
230 a >= b = case (compare a b) of { LT -> False; EQ -> True; GT -> True }
231 a > b = case (compare a b) of { LT -> False; EQ -> False; GT -> True }
233 max a b = case (compare a b) of { LT -> b; EQ -> a; GT -> a }
234 min a b = case (compare a b) of { LT -> a; EQ -> b; GT -> b }
236 -- compare to come...
240 @compare@ always has two parts. First, we use the compared
241 data-constructors' tags to deal with the case of different
244 compare a b = case (con2tag_Foo a) of { a# ->
245 case (con2tag_Foo b) of { b# ->
246 case (a# ==# b#) of {
248 False -> case (a# <# b#) of
253 cmp_eq = ... to come ...
257 We are only left with the ``help'' function @cmp_eq@, to deal with
258 comparing data constructors with the same tag.
260 For the ordinary constructors (if any), we emit the sorta-obvious
261 compare-style stuff; for our example:
263 cmp_eq (O1 a1 b1) (O1 a2 b2)
264 = case (compare a1 a2) of { LT -> LT; EQ -> compare b1 b2; GT -> GT }
266 cmp_eq (O2 a1) (O2 a2)
269 cmp_eq (O3 a1 b1 c1) (O3 a2 b2 c2)
270 = case (compare a1 a2) of {
273 EQ -> case compare b1 b2 of {
281 Again, we must be careful about unboxed comparisons. For example,
282 if \tr{a1} and \tr{a2} were \tr{Int#}s in the 2nd example above, we'd need to
286 cmp_eq lt eq gt (O2 a1) (O2 a2)
288 -- or maybe the unfolded equivalent
292 For the remaining nullary constructors, we already know that the
299 If there is only one constructor in the Data Type we don't need the WildCard Pattern.
303 gen_Ord_binds :: TyCon -> RdrNameMonoBinds
306 = defaulted `AndMonoBinds` compare
308 tycon_loc = getSrcLoc tycon
309 --------------------------------------------------------------------
310 compare = mk_easy_FunMonoBind tycon_loc compare_RDR
313 (if maybeToBool (maybeTyConSingleCon tycon) then
315 -- cmp_eq_Expr ltTag_Expr eqTag_Expr gtTag_Expr a_Expr b_Expr
316 -- Wierd. Was: case (cmp a b) of { LT -> LT; EQ -> EQ; GT -> GT }
318 cmp_eq_Expr a_Expr b_Expr
320 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)]
321 (cmp_tags_Expr eqH_Int_RDR ah_RDR bh_RDR
322 -- True case; they are equal
323 -- If an enumeration type we are done; else
324 -- recursively compare their components
325 (if isEnumerationTyCon tycon then
328 -- cmp_eq_Expr ltTag_Expr eqTag_Expr gtTag_Expr a_Expr b_Expr
330 cmp_eq_Expr a_Expr b_Expr
332 -- False case; they aren't equal
333 -- So we need to do a less-than comparison on the tags
334 (cmp_tags_Expr ltH_Int_RDR ah_RDR bh_RDR ltTag_Expr gtTag_Expr)))
336 tycon_data_cons = tyConDataCons tycon
337 (nullary_cons, nonnullary_cons)
338 | isNewTyCon tycon = ([], tyConDataCons tycon)
339 | otherwise = partition isNullaryDataCon tycon_data_cons
342 mk_FunMonoBind tycon_loc
344 (if null nonnullary_cons && (length nullary_cons == 1) then
345 -- catch this specially to avoid warnings
346 -- about overlapping patterns from the desugarer.
348 data_con = head nullary_cons
349 data_con_RDR = qual_orig_name data_con
350 pat = ConPatIn data_con_RDR []
352 [([pat,pat], eqTag_Expr)]
354 map pats_etc nonnullary_cons ++
355 -- leave out wildcards to silence desugarer.
356 (if length tycon_data_cons == 1 then
359 [([WildPatIn, WildPatIn], default_rhs)]))
362 = ([con1_pat, con2_pat],
363 nested_compare_expr tys_needed as_needed bs_needed)
365 con1_pat = ConPatIn data_con_RDR (map VarPatIn as_needed)
366 con2_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
368 data_con_RDR = qual_orig_name data_con
369 con_arity = length tys_needed
370 as_needed = take con_arity as_RDRs
371 bs_needed = take con_arity bs_RDRs
372 tys_needed = dataConRawArgTys data_con
374 nested_compare_expr [ty] [a] [b]
375 = careful_compare_Case ty ltTag_Expr eqTag_Expr gtTag_Expr (HsVar a) (HsVar b)
377 nested_compare_expr (ty:tys) (a:as) (b:bs)
378 = let eq_expr = nested_compare_expr tys as bs
379 in careful_compare_Case ty ltTag_Expr eq_expr gtTag_Expr (HsVar a) (HsVar b)
381 default_rhs | null nullary_cons = impossible_Expr -- Keep desugarer from complaining about
382 -- inexhaustive patterns
383 | otherwise = eqTag_Expr -- Some nullary constructors;
384 -- Tags are equal, no args => return EQ
385 --------------------------------------------------------------------
387 defaulted = foldr1 AndMonoBinds [lt, le, ge, gt, max_, min_]
389 lt = mk_easy_FunMonoBind mkGeneratedSrcLoc lt_RDR [a_Pat, b_Pat] [] (
390 compare_Case true_Expr false_Expr false_Expr a_Expr b_Expr)
391 le = mk_easy_FunMonoBind mkGeneratedSrcLoc le_RDR [a_Pat, b_Pat] [] (
392 compare_Case true_Expr true_Expr false_Expr a_Expr b_Expr)
393 ge = mk_easy_FunMonoBind mkGeneratedSrcLoc ge_RDR [a_Pat, b_Pat] [] (
394 compare_Case false_Expr true_Expr true_Expr a_Expr b_Expr)
395 gt = mk_easy_FunMonoBind mkGeneratedSrcLoc gt_RDR [a_Pat, b_Pat] [] (
396 compare_Case false_Expr false_Expr true_Expr a_Expr b_Expr)
398 max_ = mk_easy_FunMonoBind mkGeneratedSrcLoc max_RDR [a_Pat, b_Pat] [] (
399 compare_Case b_Expr a_Expr a_Expr a_Expr b_Expr)
400 min_ = mk_easy_FunMonoBind mkGeneratedSrcLoc min_RDR [a_Pat, b_Pat] [] (
401 compare_Case a_Expr b_Expr b_Expr a_Expr b_Expr)
404 %************************************************************************
406 \subsubsection{Generating @Enum@ instance declarations}
408 %************************************************************************
410 @Enum@ can only be derived for enumeration types. For a type
412 data Foo ... = N1 | N2 | ... | Nn
415 we use both @con2tag_Foo@ and @tag2con_Foo@ functions, as well as a
416 @maxtag_Foo@ variable (all generated by @gen_tag_n_con_binds@).
419 instance ... Enum (Foo ...) where
420 toEnum i = tag2con_Foo i
422 enumFrom a = map tag2con_Foo [con2tag_Foo a .. maxtag_Foo]
426 = case con2tag_Foo a of
427 a# -> map tag2con_Foo (enumFromTo (I# a#) maxtag_Foo)
430 = map tag2con_Foo [con2tag_Foo a, con2tag_Foo b .. maxtag_Foo]
434 = case con2tag_Foo a of { a# ->
435 case con2tag_Foo b of { b# ->
436 map tag2con_Foo (enumFromThenTo (I# a#) (I# b#) maxtag_Foo)
440 For @enumFromTo@ and @enumFromThenTo@, we use the default methods.
443 gen_Enum_binds :: TyCon -> RdrNameMonoBinds
446 = to_enum `AndMonoBinds`
447 enum_from `AndMonoBinds`
448 enum_from_then `AndMonoBinds`
451 tycon_loc = getSrcLoc tycon
454 = mk_easy_FunMonoBind tycon_loc toEnum_RDR [a_Pat] [] $
455 mk_easy_App (tag2con_RDR tycon) [a_RDR]
458 = mk_easy_FunMonoBind tycon_loc enumFrom_RDR [a_Pat] [] $
459 untag_Expr tycon [(a_RDR, ah_RDR)] $
460 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
461 HsPar (enum_from_to_Expr
462 (mk_easy_App mkInt_RDR [ah_RDR])
463 (HsVar (maxtag_RDR tycon)))
466 = mk_easy_FunMonoBind tycon_loc enumFromThen_RDR [a_Pat, b_Pat] [] $
467 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)] $
468 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
469 HsPar (enum_from_then_to_Expr
470 (mk_easy_App mkInt_RDR [ah_RDR])
471 (mk_easy_App mkInt_RDR [bh_RDR])
472 (HsVar (maxtag_RDR tycon)))
475 = mk_easy_FunMonoBind tycon_loc fromEnum_RDR [a_Pat] [] $
476 untag_Expr tycon [(a_RDR, ah_RDR)] $
477 (mk_easy_App mkInt_RDR [ah_RDR])
480 %************************************************************************
482 \subsubsection{Generating @Bounded@ instance declarations}
484 %************************************************************************
487 gen_Bounded_binds tycon
488 = if isEnumerationTyCon tycon then
489 min_bound_enum `AndMonoBinds` max_bound_enum
491 ASSERT(length data_cons == 1)
492 min_bound_1con `AndMonoBinds` max_bound_1con
494 data_cons = tyConDataCons tycon
495 tycon_loc = getSrcLoc tycon
497 ----- enum-flavored: ---------------------------
498 min_bound_enum = mk_easy_FunMonoBind tycon_loc minBound_RDR [] [] (HsVar data_con_1_RDR)
499 max_bound_enum = mk_easy_FunMonoBind tycon_loc maxBound_RDR [] [] (HsVar data_con_N_RDR)
501 data_con_1 = head data_cons
502 data_con_N = last data_cons
503 data_con_1_RDR = qual_orig_name data_con_1
504 data_con_N_RDR = qual_orig_name data_con_N
506 ----- single-constructor-flavored: -------------
507 arity = argFieldCount data_con_1
509 min_bound_1con = mk_easy_FunMonoBind tycon_loc minBound_RDR [] [] $
510 mk_easy_App data_con_1_RDR (nOfThem arity minBound_RDR)
511 max_bound_1con = mk_easy_FunMonoBind tycon_loc maxBound_RDR [] [] $
512 mk_easy_App data_con_1_RDR (nOfThem arity maxBound_RDR)
515 %************************************************************************
517 \subsubsection{Generating @Ix@ instance declarations}
519 %************************************************************************
521 Deriving @Ix@ is only possible for enumeration types and
522 single-constructor types. We deal with them in turn.
524 For an enumeration type, e.g.,
526 data Foo ... = N1 | N2 | ... | Nn
528 things go not too differently from @Enum@:
530 instance ... Ix (Foo ...) where
532 = map tag2con_Foo [con2tag_Foo a .. con2tag_Foo b]
536 = case (con2tag_Foo a) of { a# ->
537 case (con2tag_Foo b) of { b# ->
538 map tag2con_Foo (enumFromTo (I# a#) (I# b#))
543 then case (con2tag_Foo d -# con2tag_Foo a) of
545 else error "Ix.Foo.index: out of range"
549 p_tag = con2tag_Foo c
551 p_tag >= con2tag_Foo a && p_tag <= con2tag_Foo b
555 = case (con2tag_Foo a) of { a_tag ->
556 case (con2tag_Foo b) of { b_tag ->
557 case (con2tag_Foo c) of { c_tag ->
558 if (c_tag >=# a_tag) then
564 (modulo suitable case-ification to handle the unboxed tags)
566 For a single-constructor type (NB: this includes all tuples), e.g.,
568 data Foo ... = MkFoo a b Int Double c c
570 we follow the scheme given in Figure~19 of the Haskell~1.2 report
574 gen_Ix_binds :: TyCon -> RdrNameMonoBinds
577 = if isEnumerationTyCon tycon
581 tycon_str = getOccString tycon
582 tycon_loc = getSrcLoc tycon
584 --------------------------------------------------------------
585 enum_ixes = enum_range `AndMonoBinds`
586 enum_index `AndMonoBinds` enum_inRange
589 = mk_easy_FunMonoBind tycon_loc range_RDR
590 [TuplePatIn [a_Pat, b_Pat] True{-boxed-}] [] $
591 untag_Expr tycon [(a_RDR, ah_RDR)] $
592 untag_Expr tycon [(b_RDR, bh_RDR)] $
593 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
594 HsPar (enum_from_to_Expr
595 (mk_easy_App mkInt_RDR [ah_RDR])
596 (mk_easy_App mkInt_RDR [bh_RDR]))
599 = mk_easy_FunMonoBind tycon_loc index_RDR
600 [AsPatIn c_RDR (TuplePatIn [a_Pat, b_Pat] True{-boxed-}),
602 HsIf (HsPar (mk_easy_App inRange_RDR [c_RDR, d_RDR])) (
603 untag_Expr tycon [(a_RDR, ah_RDR)] (
604 untag_Expr tycon [(d_RDR, dh_RDR)] (
606 rhs = mk_easy_App mkInt_RDR [c_RDR]
609 (genOpApp (HsVar dh_RDR) minusH_RDR (HsVar ah_RDR))
610 [mkSimpleMatch [VarPatIn c_RDR] rhs Nothing tycon_loc]
614 HsApp (HsVar error_RDR) (HsLit (HsString (_PK_ ("Ix."++tycon_str++".index: out of range\n"))))
619 = mk_easy_FunMonoBind tycon_loc inRange_RDR
620 [TuplePatIn [a_Pat, b_Pat] True{-boxed-}, c_Pat] [] (
621 untag_Expr tycon [(a_RDR, ah_RDR)] (
622 untag_Expr tycon [(b_RDR, bh_RDR)] (
623 untag_Expr tycon [(c_RDR, ch_RDR)] (
624 HsIf (genOpApp (HsVar ch_RDR) geH_RDR (HsVar ah_RDR)) (
625 (genOpApp (HsVar ch_RDR) leH_RDR (HsVar bh_RDR))
630 --------------------------------------------------------------
632 = single_con_range `AndMonoBinds`
633 single_con_index `AndMonoBinds`
637 = case maybeTyConSingleCon tycon of -- just checking...
638 Nothing -> panic "get_Ix_binds"
639 Just dc -> if (any isUnLiftedType (dataConRawArgTys dc)) then
640 error ("ERROR: Can't derive Ix for a single-constructor type with primitive argument types: "++tycon_str)
644 con_arity = argFieldCount data_con
645 data_con_RDR = qual_orig_name data_con
647 as_needed = take con_arity as_RDRs
648 bs_needed = take con_arity bs_RDRs
649 cs_needed = take con_arity cs_RDRs
651 con_pat xs = ConPatIn data_con_RDR (map VarPatIn xs)
652 con_expr = mk_easy_App data_con_RDR cs_needed
654 --------------------------------------------------------------
656 = mk_easy_FunMonoBind tycon_loc range_RDR
657 [TuplePatIn [con_pat as_needed, con_pat bs_needed] True{-boxed-}] [] $
658 HsDo ListComp stmts tycon_loc
660 stmts = zipWith3Equal "single_con_range" mk_qual as_needed bs_needed cs_needed
662 [ReturnStmt con_expr]
664 mk_qual a b c = BindStmt (VarPatIn c)
665 (HsApp (HsVar range_RDR)
666 (ExplicitTuple [HsVar a, HsVar b] True))
671 = mk_easy_FunMonoBind tycon_loc index_RDR
672 [TuplePatIn [con_pat as_needed, con_pat bs_needed] True,
673 con_pat cs_needed] [range_size] (
674 foldl mk_index (HsLit (HsInt 0)) (zip3 as_needed bs_needed cs_needed))
676 mk_index multiply_by (l, u, i)
678 (HsApp (HsApp (HsVar index_RDR)
679 (ExplicitTuple [HsVar l, HsVar u] True)) (HsVar i))
682 (HsApp (HsVar rangeSize_RDR)
683 (ExplicitTuple [HsVar l, HsVar u] True))
684 ) times_RDR multiply_by
688 = mk_easy_FunMonoBind tycon_loc rangeSize_RDR
689 [TuplePatIn [a_Pat, b_Pat] True] [] (
691 (HsApp (HsApp (HsVar index_RDR)
692 (ExplicitTuple [a_Expr, b_Expr] True)) b_Expr)
693 ) plus_RDR (HsLit (HsInt 1)))
697 = mk_easy_FunMonoBind tycon_loc inRange_RDR
698 [TuplePatIn [con_pat as_needed, con_pat bs_needed] True,
701 foldl1 and_Expr (zipWith3Equal "single_con_inRange" in_range as_needed bs_needed cs_needed))
703 in_range a b c = HsApp (HsApp (HsVar inRange_RDR)
704 (ExplicitTuple [HsVar a, HsVar b] True))
708 %************************************************************************
710 \subsubsection{Generating @Read@ instance declarations}
712 %************************************************************************
714 Ignoring all the infix-ery mumbo jumbo (ToDo)
717 gen_Read_binds :: TyCon -> RdrNameMonoBinds
720 = reads_prec `AndMonoBinds` read_list
722 tycon_loc = getSrcLoc tycon
723 -----------------------------------------------------------------------
724 read_list = mk_easy_FunMonoBind tycon_loc readList_RDR [] []
725 (HsApp (HsVar readList___RDR) (HsPar (HsApp (HsVar readsPrec_RDR) (HsLit (HsInt 0)))))
726 -----------------------------------------------------------------------
729 read_con_comprehensions
730 = map read_con (tyConDataCons tycon)
732 mk_easy_FunMonoBind tycon_loc readsPrec_RDR [a_Pat, b_Pat] [] (
733 foldr1 append_Expr read_con_comprehensions
736 read_con data_con -- note: "b" is the string being "read"
738 data_con_RDR = qual_orig_name data_con
739 data_con_str= occNameString (getOccName data_con)
740 con_arity = argFieldCount data_con
741 con_expr = mk_easy_App data_con_RDR as_needed
742 nullary_con = con_arity == 0
743 labels = dataConFieldLabels data_con
744 lab_fields = length labels
746 as_needed = take con_arity as_RDRs
748 | lab_fields == 0 = take con_arity bs_RDRs
749 | otherwise = take (4*lab_fields + 1) bs_RDRs
750 -- (label, '=' and field)*n, (n-1)*',' + '{' + '}'
753 (TuplePatIn [LitPatIn (mkHsString data_con_str),
755 (HsApp (HsVar lex_RDR) c_Expr)
758 str_qual str res draw_from
760 (TuplePatIn [LitPatIn (mkHsString str), VarPatIn res] True)
761 (HsApp (HsVar lex_RDR) draw_from)
765 = let nm = occNameString (getOccName (fieldLabelName f))
767 [str_qual nm, str_qual "="]
768 -- There might be spaces between the label and '='
772 snd (mapAccumL mk_qual
774 (zipWithEqual "as_needed"
775 (\ con_field draw_from -> (mk_read_qual con_field,
777 as_needed bs_needed))
780 mapAccumL mk_qual d_Expr
781 (zipEqual "bs_needed"
784 intersperse [str_qual ","] $
787 (\ as b -> as ++ [b])
789 (map read_label labels)
791 (map mk_read_qual as_needed))) ++ [str_qual "}"])
794 mk_qual draw_from (f, str_left)
795 = (HsVar str_left, -- what to draw from down the line...
796 f str_left draw_from)
798 mk_read_qual con_field res draw_from =
800 (TuplePatIn [VarPatIn con_field, VarPatIn res] True)
801 (HsApp (HsApp (HsVar readsPrec_RDR) (HsLit (HsInt 10))) draw_from)
804 result_expr = ExplicitTuple [con_expr, if null bs_needed
806 else HsVar (last bs_needed)] True
808 stmts = con_qual:field_quals ++ [ReturnStmt result_expr]
811 = if nullary_con then -- must be False (parens are surely optional)
813 else -- parens depend on precedence...
814 HsPar (genOpApp a_Expr gt_RDR (HsLit (HsInt 9)))
817 readParen_Expr read_paren_arg $ HsPar $
818 HsLam (mk_easy_Match tycon_loc [c_Pat] [] $
819 HsDo ListComp stmts tycon_loc)
824 %************************************************************************
826 \subsubsection{Generating @Show@ instance declarations}
828 %************************************************************************
830 Ignoring all the infix-ery mumbo jumbo (ToDo)
833 gen_Show_binds :: TyCon -> RdrNameMonoBinds
836 = shows_prec `AndMonoBinds` show_list
838 tycon_loc = getSrcLoc tycon
839 -----------------------------------------------------------------------
840 show_list = mk_easy_FunMonoBind tycon_loc showList_RDR [] []
841 (HsApp (HsVar showList___RDR) (HsPar (HsApp (HsVar showsPrec_RDR) (HsLit (HsInt 0)))))
842 -----------------------------------------------------------------------
844 = mk_FunMonoBind tycon_loc showsPrec_RDR (map pats_etc (tyConDataCons tycon))
848 data_con_RDR = qual_orig_name data_con
849 con_arity = argFieldCount data_con
850 bs_needed = take con_arity bs_RDRs
851 con_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
852 nullary_con = con_arity == 0
853 labels = dataConFieldLabels data_con
854 lab_fields = length labels
857 = let nm = occNameString (getOccName data_con)
860 | lab_fields == 0 = " "
864 mk_showString_app (nm ++ space_ocurly_maybe)
869 | lab_fields > 0 = [mk_showString_app "}"]
872 con:fs ++ ccurly_maybe
874 show_thingies = show_all show_con real_show_thingies_with_labs
877 = let nm = occNameString (getOccName (fieldLabelName l))
879 mk_showString_app (nm ++ "=")
881 mk_showString_app str = HsApp (HsVar showString_RDR)
882 (HsLit (mkHsString str))
885 [ HsApp (HsApp (HsVar showsPrec_RDR) (HsLit (HsInt 10))) (HsVar b)
888 real_show_thingies_with_labs
889 | lab_fields == 0 = intersperse (HsVar showSpace_RDR) real_show_thingies
890 | otherwise = --Assumption: no of fields == no of labelled fields
891 -- (and in same order)
893 intersperse ([mk_showString_app ","]) $ -- Using SLIT()s containing ,s spells trouble.
894 zipWithEqual "gen_Show_binds"
896 (map show_label labels)
901 if nullary_con then -- skip the showParen junk...
902 ASSERT(null bs_needed)
903 ([a_Pat, con_pat], show_con)
906 showParen_Expr (HsPar (genOpApp a_Expr ge_RDR (HsLit (HsInt 10))))
907 (HsPar (nested_compose_Expr show_thingies)))
910 %************************************************************************
912 \subsection{Generating extra binds (@con2tag@ and @tag2con@)}
914 %************************************************************************
919 con2tag_Foo :: Foo ... -> Int#
920 tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
921 maxtag_Foo :: Int -- ditto (NB: not unboxed)
924 The `tags' here start at zero, hence the @fIRST_TAG@ (currently one)
929 = GenCon2Tag | GenTag2Con | GenMaxTag
931 gen_tag_n_con_monobind
932 :: (RdrName, -- (proto)Name for the thing in question
933 TyCon, -- tycon in question
937 gen_tag_n_con_monobind (rdr_name, tycon, GenCon2Tag)
938 = mk_FunMonoBind (getSrcLoc tycon) rdr_name (map mk_stuff (tyConDataCons tycon))
940 mk_stuff :: DataCon -> ([RdrNamePat], RdrNameHsExpr)
943 = ([pat], HsLit (HsIntPrim (toInteger ((dataConTag var) - fIRST_TAG))))
945 pat = ConPatIn var_RDR (nOfThem (argFieldCount var) WildPatIn)
946 var_RDR = qual_orig_name var
948 gen_tag_n_con_monobind (rdr_name, tycon, GenTag2Con)
949 = mk_FunMonoBind (getSrcLoc tycon) rdr_name (map mk_stuff (tyConDataCons tycon) ++
950 [([WildPatIn], impossible_Expr)])
952 mk_stuff :: DataCon -> ([RdrNamePat], RdrNameHsExpr)
953 mk_stuff var = ([lit_pat], HsVar var_RDR)
955 lit_pat = ConPatIn mkInt_RDR [LitPatIn (HsIntPrim (toInteger ((dataConTag var) - fIRST_TAG)))]
956 var_RDR = qual_orig_name var
958 gen_tag_n_con_monobind (rdr_name, tycon, GenMaxTag)
959 = mk_easy_FunMonoBind (getSrcLoc tycon)
960 rdr_name [] [] (HsApp (HsVar mkInt_RDR) (HsLit (HsIntPrim max_tag)))
962 max_tag = case (tyConDataCons tycon) of
963 data_cons -> toInteger ((length data_cons) - fIRST_TAG)
967 %************************************************************************
969 \subsection{Utility bits for generating bindings}
971 %************************************************************************
973 @mk_easy_FunMonoBind fun pats binds expr@ generates:
975 fun pat1 pat2 ... patN = expr where binds
978 @mk_FunMonoBind fun [([p1a, p1b, ...], e1), ...]@ is for
979 multi-clause definitions; it generates:
981 fun p1a p1b ... p1N = e1
982 fun p2a p2b ... p2N = e2
984 fun pMa pMb ... pMN = eM
988 mk_easy_FunMonoBind :: SrcLoc -> RdrName -> [RdrNamePat]
989 -> [RdrNameMonoBinds] -> RdrNameHsExpr
992 mk_easy_FunMonoBind loc fun pats binds expr
993 = FunMonoBind fun False{-not infix-} [mk_easy_Match loc pats binds expr] loc
995 mk_easy_Match loc pats binds expr
996 = mk_match loc pats expr (mkbind binds)
998 mkbind [] = EmptyBinds
999 mkbind bs = MonoBind (foldr1 AndMonoBinds bs) [] Recursive
1000 -- The renamer expects everything in its input to be a
1001 -- "recursive" MonoBinds, and it is its job to sort things out
1004 mk_FunMonoBind :: SrcLoc -> RdrName
1005 -> [([RdrNamePat], RdrNameHsExpr)]
1008 mk_FunMonoBind loc fun [] = panic "TcGenDeriv:mk_FunMonoBind"
1009 mk_FunMonoBind loc fun pats_and_exprs
1010 = FunMonoBind fun False{-not infix-}
1011 [ mk_match loc p e EmptyBinds | (p,e) <-pats_and_exprs ]
1014 mk_match loc pats expr binds
1015 = Match [] (map paren pats) Nothing
1016 (GRHSs (unguardedRHS expr loc) binds Nothing)
1018 paren p@(VarPatIn _) = p
1019 paren other_p = ParPatIn other_p
1023 mk_easy_App f xs = foldl HsApp (HsVar f) (map HsVar xs)
1026 ToDo: Better SrcLocs.
1030 RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1031 -> RdrNameHsExpr -> RdrNameHsExpr
1035 -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1036 -> RdrNameHsExpr -> RdrNameHsExpr
1038 careful_compare_Case :: -- checks for primitive types...
1040 -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1041 -> RdrNameHsExpr -> RdrNameHsExpr
1044 compare_Case = compare_gen_Case compare_RDR
1045 cmp_eq_Expr a b = HsApp (HsApp (HsVar cmp_eq_RDR) a) b
1046 -- Was: compare_gen_Case cmp_eq_RDR
1048 compare_gen_Case fun lt eq gt a b
1049 = HsCase (HsPar (HsApp (HsApp (HsVar fun) a) b)) {-of-}
1050 [mkSimpleMatch [ConPatIn ltTag_RDR []] lt Nothing mkGeneratedSrcLoc,
1051 mkSimpleMatch [ConPatIn eqTag_RDR []] eq Nothing mkGeneratedSrcLoc,
1052 mkSimpleMatch [ConPatIn gtTag_RDR []] gt Nothing mkGeneratedSrcLoc]
1055 careful_compare_Case ty lt eq gt a b
1056 = if not (isUnboxedType ty) then
1057 compare_gen_Case compare_RDR lt eq gt a b
1059 else -- we have to do something special for primitive things...
1060 HsIf (genOpApp a relevant_eq_op b)
1062 (HsIf (genOpApp a relevant_lt_op b) lt gt mkGeneratedSrcLoc)
1065 relevant_eq_op = assoc_ty_id eq_op_tbl ty
1066 relevant_lt_op = assoc_ty_id lt_op_tbl ty
1068 assoc_ty_id tyids ty
1069 = if null res then panic "assoc_ty"
1072 res = [id | (ty',id) <- tyids, ty == ty']
1075 [(charPrimTy, eqH_Char_RDR)
1076 ,(intPrimTy, eqH_Int_RDR)
1077 ,(wordPrimTy, eqH_Word_RDR)
1078 ,(addrPrimTy, eqH_Addr_RDR)
1079 ,(floatPrimTy, eqH_Float_RDR)
1080 ,(doublePrimTy, eqH_Double_RDR)
1084 [(charPrimTy, ltH_Char_RDR)
1085 ,(intPrimTy, ltH_Int_RDR)
1086 ,(wordPrimTy, ltH_Word_RDR)
1087 ,(addrPrimTy, ltH_Addr_RDR)
1088 ,(floatPrimTy, ltH_Float_RDR)
1089 ,(doublePrimTy, ltH_Double_RDR)
1092 -----------------------------------------------------------------------
1094 and_Expr, append_Expr :: RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1096 and_Expr a b = genOpApp a and_RDR b
1097 append_Expr a b = genOpApp a append_RDR b
1099 -----------------------------------------------------------------------
1101 eq_Expr :: Type -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1103 = if not (isUnboxedType ty) then
1105 else -- we have to do something special for primitive things...
1106 genOpApp a relevant_eq_op b
1108 relevant_eq_op = assoc_ty_id eq_op_tbl ty
1112 argFieldCount :: DataCon -> Int -- Works on data and newtype constructors
1113 argFieldCount con = length (dataConRawArgTys con)
1117 untag_Expr :: TyCon -> [(RdrName, RdrName)] -> RdrNameHsExpr -> RdrNameHsExpr
1118 untag_Expr tycon [] expr = expr
1119 untag_Expr tycon ((untag_this, put_tag_here) : more) expr
1120 = HsCase (HsPar (HsApp (con2tag_Expr tycon) (HsVar untag_this))) {-of-}
1121 [mkSimpleMatch [VarPatIn put_tag_here] (untag_Expr tycon more expr) Nothing mkGeneratedSrcLoc]
1124 cmp_tags_Expr :: RdrName -- Comparison op
1125 -> RdrName -> RdrName -- Things to compare
1126 -> RdrNameHsExpr -- What to return if true
1127 -> RdrNameHsExpr -- What to return if false
1130 cmp_tags_Expr op a b true_case false_case
1131 = HsIf (genOpApp (HsVar a) op (HsVar b)) true_case false_case mkGeneratedSrcLoc
1134 :: RdrNameHsExpr -> RdrNameHsExpr
1136 enum_from_then_to_Expr
1137 :: RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1140 enum_from_to_Expr f t2 = HsApp (HsApp (HsVar enumFromTo_RDR) f) t2
1141 enum_from_then_to_Expr f t t2 = HsApp (HsApp (HsApp (HsVar enumFromThenTo_RDR) f) t) t2
1143 showParen_Expr, readParen_Expr
1144 :: RdrNameHsExpr -> RdrNameHsExpr
1147 showParen_Expr e1 e2 = HsApp (HsApp (HsVar showParen_RDR) e1) e2
1148 readParen_Expr e1 e2 = HsApp (HsApp (HsVar readParen_RDR) e1) e2
1150 nested_compose_Expr :: [RdrNameHsExpr] -> RdrNameHsExpr
1152 nested_compose_Expr [e] = parenify e
1153 nested_compose_Expr (e:es)
1154 = HsApp (HsApp (HsVar compose_RDR) (parenify e)) (nested_compose_Expr es)
1156 -- impossible_Expr is used in case RHSs that should never happen.
1157 -- We generate these to keep the desugarer from complaining that they *might* happen!
1158 impossible_Expr = HsApp (HsVar error_RDR) (HsLit (HsString (_PK_ "Urk! in TcGenDeriv")))
1160 parenify e@(HsVar _) = e
1161 parenify e = HsPar e
1163 -- genOpApp wraps brackets round the operator application, so that the
1164 -- renamer won't subsequently try to re-associate it.
1165 -- For some reason the renamer doesn't reassociate it right, and I can't
1166 -- be bothered to find out why just now.
1168 genOpApp e1 op e2 = mkOpApp e1 op e2
1172 qual_orig_name n = case modAndOcc n of { (m,n) -> Qual m n HiFile }
1174 a_RDR = varUnqual SLIT("a")
1175 b_RDR = varUnqual SLIT("b")
1176 c_RDR = varUnqual SLIT("c")
1177 d_RDR = varUnqual SLIT("d")
1178 ah_RDR = varUnqual SLIT("a#")
1179 bh_RDR = varUnqual SLIT("b#")
1180 ch_RDR = varUnqual SLIT("c#")
1181 dh_RDR = varUnqual SLIT("d#")
1182 cmp_eq_RDR = varUnqual SLIT("cmp_eq")
1183 rangeSize_RDR = varUnqual SLIT("rangeSize")
1185 as_RDRs = [ varUnqual (_PK_ ("a"++show i)) | i <- [(1::Int) .. ] ]
1186 bs_RDRs = [ varUnqual (_PK_ ("b"++show i)) | i <- [(1::Int) .. ] ]
1187 cs_RDRs = [ varUnqual (_PK_ ("c"++show i)) | i <- [(1::Int) .. ] ]
1189 mkHsString s = HsString (_PK_ s)
1191 a_Expr = HsVar a_RDR
1192 b_Expr = HsVar b_RDR
1193 c_Expr = HsVar c_RDR
1194 d_Expr = HsVar d_RDR
1195 ltTag_Expr = HsVar ltTag_RDR
1196 eqTag_Expr = HsVar eqTag_RDR
1197 gtTag_Expr = HsVar gtTag_RDR
1198 false_Expr = HsVar false_RDR
1199 true_Expr = HsVar true_RDR
1201 con2tag_Expr tycon = HsVar (con2tag_RDR tycon)
1203 a_Pat = VarPatIn a_RDR
1204 b_Pat = VarPatIn b_RDR
1205 c_Pat = VarPatIn c_RDR
1206 d_Pat = VarPatIn d_RDR
1208 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon -> RdrName
1210 con2tag_RDR tycon = varUnqual (_PK_ ("con2tag_" ++ occNameString (getOccName tycon) ++ "#"))
1211 tag2con_RDR tycon = varUnqual (_PK_ ("tag2con_" ++ occNameString (getOccName tycon) ++ "#"))
1212 maxtag_RDR tycon = varUnqual (_PK_ ("maxtag_" ++ occNameString (getOccName tycon) ++ "#"))