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(..), HsType(..), HsDoContext(..),
32 unguardedRHS, mkSimpleMatch, mkMonoBind, andMonoBindList, placeHolderType
34 import RdrHsSyn ( mkHsOpApp, RdrNameMonoBinds, RdrNameHsExpr, RdrNamePat )
35 import RdrName ( RdrName, mkUnqual )
36 import BasicTypes ( RecFlag(..), Fixity(..), FixityDirection(..)
40 import FieldLabel ( fieldLabelName )
41 import DataCon ( isNullaryDataCon, dataConTag,
42 dataConOrigArgTys, dataConSourceArity, fIRST_TAG,
45 import Name ( getOccString, getOccName, getSrcLoc, occNameString,
46 occNameUserString, nameRdrName, varName,
48 isDataSymOcc, isSymOcc
51 import HscTypes ( FixityEnv, lookupFixity )
52 import PrelInfo -- Lots of RdrNames
53 import SrcLoc ( generatedSrcLoc, SrcLoc )
54 import TyCon ( TyCon, isNewTyCon, tyConDataCons, isEnumerationTyCon,
55 maybeTyConSingleCon, tyConFamilySize
57 import TcType ( isUnLiftedType, tcEqType, Type )
58 import TysPrim ( charPrimTy, intPrimTy, wordPrimTy, addrPrimTy,
59 floatPrimTy, doublePrimTy
61 import Util ( mapAccumL, zipEqual, zipWithEqual, isSingleton,
62 zipWith3Equal, nOfThem )
63 import Panic ( panic, assertPanic )
64 import Maybes ( maybeToBool )
66 import List ( partition, intersperse )
68 #if __GLASGOW_HASKELL__ >= 404
69 import GlaExts ( fromInt )
73 %************************************************************************
75 \subsection{Generating code, by derivable class}
77 %************************************************************************
79 %************************************************************************
81 \subsubsection{Generating @Eq@ instance declarations}
83 %************************************************************************
85 Here are the heuristics for the code we generate for @Eq@:
88 Let's assume we have a data type with some (possibly zero) nullary
89 data constructors and some ordinary, non-nullary ones (the rest,
90 also possibly zero of them). Here's an example, with both \tr{N}ullary
91 and \tr{O}rdinary data cons.
93 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
97 For the ordinary constructors (if any), we emit clauses to do The
101 (==) (O1 a1 b1) (O1 a2 b2) = a1 == a2 && b1 == b2
102 (==) (O2 a1) (O2 a2) = a1 == a2
103 (==) (O3 a1 b1 c1) (O3 a2 b2 c2) = a1 == a2 && b1 == b2 && c1 == c2
106 Note: if we're comparing unlifted things, e.g., if \tr{a1} and
107 \tr{a2} are \tr{Float#}s, then we have to generate
109 case (a1 `eqFloat#` a2) of
112 for that particular test.
115 If there are any nullary constructors, we emit a catch-all clause of
119 (==) a b = case (con2tag_Foo a) of { a# ->
120 case (con2tag_Foo b) of { b# ->
121 case (a# ==# b#) of {
126 If there aren't any nullary constructors, we emit a simpler
133 For the @(/=)@ method, we normally just use the default method.
135 If the type is an enumeration type, we could/may/should? generate
136 special code that calls @con2tag_Foo@, much like for @(==)@ shown
140 We thought about doing this: If we're also deriving @Ord@ for this
143 instance ... Eq (Foo ...) where
144 (==) a b = case (compare a b) of { _LT -> False; _EQ -> True ; _GT -> False}
145 (/=) a b = case (compare a b) of { _LT -> True ; _EQ -> False; _GT -> True }
147 However, that requires that \tr{Ord <whatever>} was put in the context
148 for the instance decl, which it probably wasn't, so the decls
149 produced don't get through the typechecker.
153 deriveEq :: RdrName -- Class
154 -> RdrName -- Type constructor
155 -> [ (RdrName, [RdrType]) ] -- Constructors
156 -> (RdrContext, -- Context for the inst decl
157 [RdrBind], -- Binds in the inst decl
158 [RdrBind]) -- Extra value bindings outside
160 deriveEq clas tycon constrs
161 = (context, [eq_bind, ne_bind], [])
163 context = [(clas, [ty]) | (_, tys) <- constrs, ty <- tys]
166 (nullary_cons, non_nullary_cons) = partition is_nullary constrs
167 is_nullary (_, args) = null args
170 gen_Eq_binds :: TyCon -> RdrNameMonoBinds
174 tycon_loc = getSrcLoc tycon
175 (nullary_cons, nonnullary_cons)
176 | isNewTyCon tycon = ([], tyConDataCons tycon)
177 | otherwise = partition isNullaryDataCon (tyConDataCons tycon)
180 = if (null nullary_cons) then
181 case maybeTyConSingleCon tycon of
183 Nothing -> -- if cons don't match, then False
184 [([wildPat, wildPat], false_Expr)]
185 else -- calc. and compare the tags
187 untag_Expr tycon [(a_RDR,ah_RDR), (b_RDR,bh_RDR)]
188 (genOpApp (HsVar ah_RDR) eqH_Int_RDR (HsVar bh_RDR)))]
190 mk_FunMonoBind tycon_loc eq_RDR ((map pats_etc nonnullary_cons) ++ rest)
192 mk_easy_FunMonoBind tycon_loc ne_RDR [a_Pat, b_Pat] [] (
193 HsApp (HsVar not_RDR) (HsPar (mk_easy_App eq_RDR [a_RDR, b_RDR])))
195 ------------------------------------------------------------------
198 con1_pat = ConPatIn data_con_RDR (map VarPatIn as_needed)
199 con2_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
201 data_con_RDR = qual_orig_name data_con
202 con_arity = length tys_needed
203 as_needed = take con_arity as_RDRs
204 bs_needed = take con_arity bs_RDRs
205 tys_needed = dataConOrigArgTys data_con
207 ([con1_pat, con2_pat], nested_eq_expr tys_needed as_needed bs_needed)
209 nested_eq_expr [] [] [] = true_Expr
210 nested_eq_expr tys as bs
211 = foldl1 and_Expr (zipWith3Equal "nested_eq" nested_eq tys as bs)
213 nested_eq ty a b = HsPar (eq_Expr ty (HsVar a) (HsVar b))
216 %************************************************************************
218 \subsubsection{Generating @Ord@ instance declarations}
220 %************************************************************************
222 For a derived @Ord@, we concentrate our attentions on @compare@
224 compare :: a -> a -> Ordering
225 data Ordering = LT | EQ | GT deriving ()
228 We will use the same example data type as above:
230 data Foo ... = N1 | N2 ... | Nn | O1 a b | O2 Int | O3 Double b b | ...
235 We do all the other @Ord@ methods with calls to @compare@:
237 instance ... (Ord <wurble> <wurble>) where
238 a < b = case (compare a b) of { LT -> True; EQ -> False; GT -> False }
239 a <= b = case (compare a b) of { LT -> True; EQ -> True; GT -> False }
240 a >= b = case (compare a b) of { LT -> False; EQ -> True; GT -> True }
241 a > b = case (compare a b) of { LT -> False; EQ -> False; GT -> True }
243 max a b = case (compare a b) of { LT -> b; EQ -> a; GT -> a }
244 min a b = case (compare a b) of { LT -> a; EQ -> b; GT -> b }
246 -- compare to come...
250 @compare@ always has two parts. First, we use the compared
251 data-constructors' tags to deal with the case of different
254 compare a b = case (con2tag_Foo a) of { a# ->
255 case (con2tag_Foo b) of { b# ->
256 case (a# ==# b#) of {
258 False -> case (a# <# b#) of
263 cmp_eq = ... to come ...
267 We are only left with the ``help'' function @cmp_eq@, to deal with
268 comparing data constructors with the same tag.
270 For the ordinary constructors (if any), we emit the sorta-obvious
271 compare-style stuff; for our example:
273 cmp_eq (O1 a1 b1) (O1 a2 b2)
274 = case (compare a1 a2) of { LT -> LT; EQ -> compare b1 b2; GT -> GT }
276 cmp_eq (O2 a1) (O2 a2)
279 cmp_eq (O3 a1 b1 c1) (O3 a2 b2 c2)
280 = case (compare a1 a2) of {
283 EQ -> case compare b1 b2 of {
291 Again, we must be careful about unlifted comparisons. For example,
292 if \tr{a1} and \tr{a2} were \tr{Int#}s in the 2nd example above, we'd need to
296 cmp_eq lt eq gt (O2 a1) (O2 a2)
298 -- or maybe the unfolded equivalent
302 For the remaining nullary constructors, we already know that the
309 If there is only one constructor in the Data Type we don't need the WildCard Pattern.
313 gen_Ord_binds :: TyCon -> RdrNameMonoBinds
316 = compare -- `AndMonoBinds` compare
317 -- The default declaration in PrelBase handles this
319 tycon_loc = getSrcLoc tycon
320 --------------------------------------------------------------------
321 compare = mk_easy_FunMonoBind tycon_loc compare_RDR
324 (if maybeToBool (maybeTyConSingleCon tycon) then
326 -- cmp_eq_Expr ltTag_Expr eqTag_Expr gtTag_Expr a_Expr b_Expr
327 -- Weird. Was: case (cmp a b) of { LT -> LT; EQ -> EQ; GT -> GT }
329 cmp_eq_Expr a_Expr b_Expr
331 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)]
332 (cmp_tags_Expr eqH_Int_RDR ah_RDR bh_RDR
333 -- True case; they are equal
334 -- If an enumeration type we are done; else
335 -- recursively compare their components
336 (if isEnumerationTyCon tycon then
339 -- cmp_eq_Expr ltTag_Expr eqTag_Expr gtTag_Expr a_Expr b_Expr
341 cmp_eq_Expr a_Expr b_Expr
343 -- False case; they aren't equal
344 -- So we need to do a less-than comparison on the tags
345 (cmp_tags_Expr ltH_Int_RDR ah_RDR bh_RDR ltTag_Expr gtTag_Expr)))
347 tycon_data_cons = tyConDataCons tycon
348 (nullary_cons, nonnullary_cons)
349 | isNewTyCon tycon = ([], tyConDataCons tycon)
350 | otherwise = partition isNullaryDataCon tycon_data_cons
353 mk_FunMonoBind tycon_loc
355 (if null nonnullary_cons && isSingleton nullary_cons then
356 -- catch this specially to avoid warnings
357 -- about overlapping patterns from the desugarer.
359 data_con = head nullary_cons
360 data_con_RDR = qual_orig_name data_con
361 pat = ConPatIn data_con_RDR []
363 [([pat,pat], eqTag_Expr)]
365 map pats_etc nonnullary_cons ++
366 -- leave out wildcards to silence desugarer.
367 (if isSingleton tycon_data_cons then
370 [([WildPatIn, WildPatIn], default_rhs)]))
373 = ([con1_pat, con2_pat],
374 nested_compare_expr tys_needed as_needed bs_needed)
376 con1_pat = ConPatIn data_con_RDR (map VarPatIn as_needed)
377 con2_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
379 data_con_RDR = qual_orig_name data_con
380 con_arity = length tys_needed
381 as_needed = take con_arity as_RDRs
382 bs_needed = take con_arity bs_RDRs
383 tys_needed = dataConOrigArgTys data_con
385 nested_compare_expr [ty] [a] [b]
386 = careful_compare_Case ty ltTag_Expr eqTag_Expr gtTag_Expr (HsVar a) (HsVar b)
388 nested_compare_expr (ty:tys) (a:as) (b:bs)
389 = let eq_expr = nested_compare_expr tys as bs
390 in careful_compare_Case ty ltTag_Expr eq_expr gtTag_Expr (HsVar a) (HsVar b)
392 default_rhs | null nullary_cons = impossible_Expr -- Keep desugarer from complaining about
393 -- inexhaustive patterns
394 | otherwise = eqTag_Expr -- Some nullary constructors;
395 -- Tags are equal, no args => return EQ
398 %************************************************************************
400 \subsubsection{Generating @Enum@ instance declarations}
402 %************************************************************************
404 @Enum@ can only be derived for enumeration types. For a type
406 data Foo ... = N1 | N2 | ... | Nn
409 we use both @con2tag_Foo@ and @tag2con_Foo@ functions, as well as a
410 @maxtag_Foo@ variable (all generated by @gen_tag_n_con_binds@).
413 instance ... Enum (Foo ...) where
414 succ x = toEnum (1 + fromEnum x)
415 pred x = toEnum (fromEnum x - 1)
417 toEnum i = tag2con_Foo i
419 enumFrom a = map tag2con_Foo [con2tag_Foo a .. maxtag_Foo]
423 = case con2tag_Foo a of
424 a# -> map tag2con_Foo (enumFromTo (I# a#) maxtag_Foo)
427 = map tag2con_Foo [con2tag_Foo a, con2tag_Foo b .. maxtag_Foo]
431 = case con2tag_Foo a of { a# ->
432 case con2tag_Foo b of { b# ->
433 map tag2con_Foo (enumFromThenTo (I# a#) (I# b#) maxtag_Foo)
437 For @enumFromTo@ and @enumFromThenTo@, we use the default methods.
440 gen_Enum_binds :: TyCon -> RdrNameMonoBinds
443 = succ_enum `AndMonoBinds`
444 pred_enum `AndMonoBinds`
445 to_enum `AndMonoBinds`
446 enum_from `AndMonoBinds`
447 enum_from_then `AndMonoBinds`
450 tycon_loc = getSrcLoc tycon
451 occ_nm = getOccString tycon
454 = mk_easy_FunMonoBind tycon_loc succ_RDR [a_Pat] [] $
455 untag_Expr tycon [(a_RDR, ah_RDR)] $
456 HsIf (HsApp (HsApp (HsVar eq_RDR)
457 (HsVar (maxtag_RDR tycon)))
458 (mk_easy_App mkInt_RDR [ah_RDR]))
459 (illegal_Expr "succ" occ_nm "tried to take `succ' of last tag in enumeration")
460 (HsApp (HsVar (tag2con_RDR tycon))
461 (HsApp (HsApp (HsVar plus_RDR)
462 (mk_easy_App mkInt_RDR [ah_RDR]))
467 = mk_easy_FunMonoBind tycon_loc pred_RDR [a_Pat] [] $
468 untag_Expr tycon [(a_RDR, ah_RDR)] $
469 HsIf (HsApp (HsApp (HsVar eq_RDR) (HsLit (HsInt 0)))
470 (mk_easy_App mkInt_RDR [ah_RDR]))
471 (illegal_Expr "pred" occ_nm "tried to take `pred' of first tag in enumeration")
472 (HsApp (HsVar (tag2con_RDR tycon))
473 (HsApp (HsApp (HsVar plus_RDR)
474 (mk_easy_App mkInt_RDR [ah_RDR]))
475 (HsLit (HsInt (-1)))))
479 = mk_easy_FunMonoBind tycon_loc toEnum_RDR [a_Pat] [] $
482 (HsApp (HsApp (HsVar ge_RDR)
485 (HsApp (HsApp (HsVar le_RDR)
487 (HsVar (maxtag_RDR tycon))))
488 (mk_easy_App (tag2con_RDR tycon) [a_RDR])
489 (illegal_toEnum_tag occ_nm (maxtag_RDR tycon))
493 = mk_easy_FunMonoBind tycon_loc enumFrom_RDR [a_Pat] [] $
494 untag_Expr tycon [(a_RDR, ah_RDR)] $
495 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
496 HsPar (enum_from_to_Expr
497 (mk_easy_App mkInt_RDR [ah_RDR])
498 (HsVar (maxtag_RDR tycon)))
501 = mk_easy_FunMonoBind tycon_loc enumFromThen_RDR [a_Pat, b_Pat] [] $
502 untag_Expr tycon [(a_RDR, ah_RDR), (b_RDR, bh_RDR)] $
503 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
504 HsPar (enum_from_then_to_Expr
505 (mk_easy_App mkInt_RDR [ah_RDR])
506 (mk_easy_App mkInt_RDR [bh_RDR])
507 (HsIf (HsApp (HsApp (HsVar gt_RDR)
508 (mk_easy_App mkInt_RDR [ah_RDR]))
509 (mk_easy_App mkInt_RDR [bh_RDR]))
511 (HsVar (maxtag_RDR tycon))
515 = mk_easy_FunMonoBind tycon_loc fromEnum_RDR [a_Pat] [] $
516 untag_Expr tycon [(a_RDR, ah_RDR)] $
517 (mk_easy_App mkInt_RDR [ah_RDR])
520 %************************************************************************
522 \subsubsection{Generating @Bounded@ instance declarations}
524 %************************************************************************
527 gen_Bounded_binds tycon
528 = if isEnumerationTyCon tycon then
529 min_bound_enum `AndMonoBinds` max_bound_enum
531 ASSERT(isSingleton data_cons)
532 min_bound_1con `AndMonoBinds` max_bound_1con
534 data_cons = tyConDataCons tycon
535 tycon_loc = getSrcLoc tycon
537 ----- enum-flavored: ---------------------------
538 min_bound_enum = mk_easy_FunMonoBind tycon_loc minBound_RDR [] [] (HsVar data_con_1_RDR)
539 max_bound_enum = mk_easy_FunMonoBind tycon_loc maxBound_RDR [] [] (HsVar data_con_N_RDR)
541 data_con_1 = head data_cons
542 data_con_N = last data_cons
543 data_con_1_RDR = qual_orig_name data_con_1
544 data_con_N_RDR = qual_orig_name data_con_N
546 ----- single-constructor-flavored: -------------
547 arity = dataConSourceArity data_con_1
549 min_bound_1con = mk_easy_FunMonoBind tycon_loc minBound_RDR [] [] $
550 mk_easy_App data_con_1_RDR (nOfThem arity minBound_RDR)
551 max_bound_1con = mk_easy_FunMonoBind tycon_loc maxBound_RDR [] [] $
552 mk_easy_App data_con_1_RDR (nOfThem arity maxBound_RDR)
555 %************************************************************************
557 \subsubsection{Generating @Ix@ instance declarations}
559 %************************************************************************
561 Deriving @Ix@ is only possible for enumeration types and
562 single-constructor types. We deal with them in turn.
564 For an enumeration type, e.g.,
566 data Foo ... = N1 | N2 | ... | Nn
568 things go not too differently from @Enum@:
570 instance ... Ix (Foo ...) where
572 = map tag2con_Foo [con2tag_Foo a .. con2tag_Foo b]
576 = case (con2tag_Foo a) of { a# ->
577 case (con2tag_Foo b) of { b# ->
578 map tag2con_Foo (enumFromTo (I# a#) (I# b#))
583 then case (con2tag_Foo d -# con2tag_Foo a) of
585 else error "Ix.Foo.index: out of range"
589 p_tag = con2tag_Foo c
591 p_tag >= con2tag_Foo a && p_tag <= con2tag_Foo b
595 = case (con2tag_Foo a) of { a_tag ->
596 case (con2tag_Foo b) of { b_tag ->
597 case (con2tag_Foo c) of { c_tag ->
598 if (c_tag >=# a_tag) then
604 (modulo suitable case-ification to handle the unlifted tags)
606 For a single-constructor type (NB: this includes all tuples), e.g.,
608 data Foo ... = MkFoo a b Int Double c c
610 we follow the scheme given in Figure~19 of the Haskell~1.2 report
614 gen_Ix_binds :: TyCon -> RdrNameMonoBinds
617 = if isEnumerationTyCon tycon
621 tycon_str = getOccString tycon
622 tycon_loc = getSrcLoc tycon
624 --------------------------------------------------------------
625 enum_ixes = enum_range `AndMonoBinds`
626 enum_index `AndMonoBinds` enum_inRange
629 = mk_easy_FunMonoBind tycon_loc range_RDR
630 [TuplePatIn [a_Pat, b_Pat] Boxed] [] $
631 untag_Expr tycon [(a_RDR, ah_RDR)] $
632 untag_Expr tycon [(b_RDR, bh_RDR)] $
633 HsApp (mk_easy_App map_RDR [tag2con_RDR tycon]) $
634 HsPar (enum_from_to_Expr
635 (mk_easy_App mkInt_RDR [ah_RDR])
636 (mk_easy_App mkInt_RDR [bh_RDR]))
639 = mk_easy_FunMonoBind tycon_loc index_RDR
640 [AsPatIn c_RDR (TuplePatIn [a_Pat, wildPat] Boxed),
642 HsIf (HsPar (mk_easy_App inRange_RDR [c_RDR, d_RDR])) (
643 untag_Expr tycon [(a_RDR, ah_RDR)] (
644 untag_Expr tycon [(d_RDR, dh_RDR)] (
646 rhs = mk_easy_App mkInt_RDR [c_RDR]
649 (genOpApp (HsVar dh_RDR) minusH_RDR (HsVar ah_RDR))
650 [mkSimpleMatch [VarPatIn c_RDR] rhs placeHolderType tycon_loc]
654 HsApp (HsVar error_RDR) (HsLit (HsString (_PK_ ("Ix."++tycon_str++".index: out of range\n"))))
659 = mk_easy_FunMonoBind tycon_loc inRange_RDR
660 [TuplePatIn [a_Pat, b_Pat] Boxed, c_Pat] [] (
661 untag_Expr tycon [(a_RDR, ah_RDR)] (
662 untag_Expr tycon [(b_RDR, bh_RDR)] (
663 untag_Expr tycon [(c_RDR, ch_RDR)] (
664 HsIf (genOpApp (HsVar ch_RDR) geH_RDR (HsVar ah_RDR)) (
665 (genOpApp (HsVar ch_RDR) leH_RDR (HsVar bh_RDR))
670 --------------------------------------------------------------
672 = single_con_range `AndMonoBinds`
673 single_con_index `AndMonoBinds`
677 = case maybeTyConSingleCon tycon of -- just checking...
678 Nothing -> panic "get_Ix_binds"
679 Just dc -> if (any isUnLiftedType (dataConOrigArgTys dc)) then
680 error ("ERROR: Can't derive Ix for a single-constructor type with primitive argument types: "++tycon_str)
684 con_arity = dataConSourceArity data_con
685 data_con_RDR = qual_orig_name data_con
687 as_needed = take con_arity as_RDRs
688 bs_needed = take con_arity bs_RDRs
689 cs_needed = take con_arity cs_RDRs
691 con_pat xs = ConPatIn data_con_RDR (map VarPatIn xs)
692 con_expr = mk_easy_App data_con_RDR cs_needed
694 --------------------------------------------------------------
696 = mk_easy_FunMonoBind tycon_loc range_RDR
697 [TuplePatIn [con_pat as_needed, con_pat bs_needed] Boxed] [] $
698 HsDo ListComp stmts tycon_loc
700 stmts = zipWith3Equal "single_con_range" mk_qual as_needed bs_needed cs_needed
702 [ResultStmt con_expr tycon_loc]
704 mk_qual a b c = BindStmt (VarPatIn c)
705 (HsApp (HsVar range_RDR)
706 (ExplicitTuple [HsVar a, HsVar b] Boxed))
711 = mk_easy_FunMonoBind tycon_loc index_RDR
712 [TuplePatIn [con_pat as_needed, con_pat bs_needed] Boxed,
713 con_pat cs_needed] [range_size] (
714 foldl mk_index (HsLit (HsInt 0)) (zip3 as_needed bs_needed cs_needed))
716 mk_index multiply_by (l, u, i)
718 (HsApp (HsApp (HsVar index_RDR)
719 (ExplicitTuple [HsVar l, HsVar u] Boxed)) (HsVar i))
722 (HsApp (HsVar rangeSize_RDR)
723 (ExplicitTuple [HsVar l, HsVar u] Boxed))
724 ) times_RDR multiply_by
728 = mk_easy_FunMonoBind tycon_loc rangeSize_RDR
729 [TuplePatIn [a_Pat, b_Pat] Boxed] [] (
731 (HsApp (HsApp (HsVar index_RDR)
732 (ExplicitTuple [a_Expr, b_Expr] Boxed)) b_Expr)
733 ) plus_RDR (HsLit (HsInt 1)))
737 = mk_easy_FunMonoBind tycon_loc inRange_RDR
738 [TuplePatIn [con_pat as_needed, con_pat bs_needed] Boxed,
741 foldl1 and_Expr (zipWith3Equal "single_con_inRange" in_range as_needed bs_needed cs_needed))
743 in_range a b c = HsApp (HsApp (HsVar inRange_RDR)
744 (ExplicitTuple [HsVar a, HsVar b] Boxed))
748 %************************************************************************
750 \subsubsection{Generating @Read@ instance declarations}
752 %************************************************************************
755 gen_Read_binds :: FixityEnv -> TyCon -> RdrNameMonoBinds
757 gen_Read_binds get_fixity tycon
758 = reads_prec `AndMonoBinds` read_list
760 tycon_loc = getSrcLoc tycon
761 -----------------------------------------------------------------------
762 read_list = mk_easy_FunMonoBind tycon_loc readList_RDR [] []
763 (HsApp (HsVar readList___RDR) (HsPar (HsApp (HsVar readsPrec_RDR) (HsLit (HsInt 0)))))
764 -----------------------------------------------------------------------
767 read_con_comprehensions
768 = map read_con (tyConDataCons tycon)
770 mk_easy_FunMonoBind tycon_loc readsPrec_RDR [zz_a_Pat, b_Pat] [] (
771 foldr1 append_Expr read_con_comprehensions
774 read_con data_con -- note: "b" is the string being "read"
776 readParen_Expr read_paren_arg $ HsPar $
777 HsLam (mk_easy_Match tycon_loc [c_Pat] [] $
778 HsDo ListComp stmts tycon_loc)
781 data_con_RDR = qual_orig_name data_con
782 data_con_str = occNameUserString (getOccName data_con)
783 con_arity = dataConSourceArity data_con
784 con_expr = mk_easy_App data_con_RDR as_needed
785 nullary_con = con_arity == 0
786 labels = dataConFieldLabels data_con
787 lab_fields = length labels
788 dc_nm = getName data_con
789 is_infix = isDataSymOcc (getOccName dc_nm)
791 as_needed = take con_arity as_RDRs
793 | is_infix = take (1 + con_arity) bs_RDRs
794 | lab_fields == 0 = take con_arity bs_RDRs
795 | otherwise = take (4*lab_fields + 1) bs_RDRs
796 -- (label, '=' and field)*n, (n-1)*',' + '{' + '}'
798 (as1:as2:_) = as_needed
799 (bs1:bs2:bs3:_) = bs_needed
804 (TuplePatIn [LitPatIn (mkHsString data_con_str), d_Pat] Boxed)
805 (HsApp (HsVar lex_RDR) c_Expr)
809 (TuplePatIn [LitPatIn (mkHsString data_con_str), VarPatIn bs2] Boxed)
810 (HsApp (HsVar lex_RDR) (HsVar bs1))
814 str_qual str res draw_from =
816 (TuplePatIn [LitPatIn (mkHsString str), VarPatIn res] Boxed)
817 (HsApp (HsVar lex_RDR) draw_from)
820 str_qual_paren str res draw_from =
822 (TuplePatIn [LitPatIn (mkHsString str), VarPatIn res] Boxed)
823 (HsApp (readParen_Expr true_Expr (HsVar lex_RDR)) draw_from)
826 read_label f = [rd_lab, str_qual "="]
827 -- There might be spaces between the label and '='
830 | is_op = str_qual_paren nm
831 | otherwise = str_qual nm
833 occ_nm = getOccName (fieldLabelName f)
834 is_op = isSymOcc occ_nm
835 nm = occNameUserString occ_nm
839 snd (mapAccumL mk_qual_infix
841 [ (mk_read_qual lp as1, bs1, bs2)
842 , (mk_read_qual rp as2, bs3, bs3)
844 | lab_fields == 0 = -- common case.
845 snd (mapAccumL mk_qual
847 (zipWithEqual "as_needed"
848 (\ con_field draw_from -> (mk_read_qual 10 con_field,
850 as_needed bs_needed))
853 mapAccumL mk_qual d_Expr
854 (zipEqual "bs_needed"
857 intersperse [str_qual ","] $
860 (\ as b -> as ++ [b])
862 (map read_label labels)
864 (map (mk_read_qual 10) as_needed))) ++ [str_qual "}"])
867 mk_qual_infix draw_from (f, str_left, str_left2) =
868 (HsVar str_left2, -- what to draw from down the line...
869 f str_left draw_from)
871 mk_qual draw_from (f, str_left) =
872 (HsVar str_left, -- what to draw from down the line...
873 f str_left draw_from)
875 mk_read_qual p con_field res draw_from =
877 (TuplePatIn [VarPatIn con_field, VarPatIn res] Boxed)
878 (HsApp (HsApp (HsVar readsPrec_RDR) (HsLit (HsInt p))) draw_from)
881 result_expr = ExplicitTuple [con_expr, if null bs_needed
883 else HsVar (last bs_needed)] Boxed
885 [lp,rp] = getLRPrecs is_infix get_fixity dc_nm
888 | is_infix = let (h:t) = field_quals in (h:con_qual:t)
889 | otherwise = con_qual:field_quals
891 stmts = quals ++ [ResultStmt result_expr tycon_loc]
894 c.f. Figure 18 in Haskell 1.1 report.
897 | not is_infix = defaultPrecedence
898 | otherwise = getPrecedence get_fixity dc_nm
900 read_paren_arg -- parens depend on precedence...
901 | nullary_con = false_Expr -- it's optional.
902 | otherwise = HsPar (genOpApp zz_a_Expr gt_RDR (HsLit (HsInt paren_prec_limit)))
905 %************************************************************************
907 \subsubsection{Generating @Show@ instance declarations}
909 %************************************************************************
912 gen_Show_binds :: FixityEnv -> TyCon -> RdrNameMonoBinds
914 gen_Show_binds get_fixity tycon
915 = shows_prec `AndMonoBinds` show_list
917 tycon_loc = getSrcLoc tycon
918 -----------------------------------------------------------------------
919 show_list = mk_easy_FunMonoBind tycon_loc showList_RDR [] []
920 (HsApp (HsVar showList___RDR) (HsPar (HsApp (HsVar showsPrec_RDR) (HsLit (HsInt 0)))))
921 -----------------------------------------------------------------------
922 shows_prec = mk_FunMonoBind tycon_loc showsPrec_RDR (map pats_etc (tyConDataCons tycon))
925 | nullary_con = -- skip the showParen junk...
926 ASSERT(null bs_needed)
927 ([wildPat, con_pat], show_con)
930 showParen_Expr (HsPar (genOpApp a_Expr ge_RDR (HsLit (HsInt paren_prec_limit))))
931 (HsPar (nested_compose_Expr show_thingies)))
933 data_con_RDR = qual_orig_name data_con
934 con_arity = dataConSourceArity data_con
935 bs_needed = take con_arity bs_RDRs
936 con_pat = ConPatIn data_con_RDR (map VarPatIn bs_needed)
937 nullary_con = con_arity == 0
938 labels = dataConFieldLabels data_con
939 lab_fields = length labels
941 dc_nm = getName data_con
942 dc_occ_nm = getOccName data_con
943 dc_occ_nm_str = occNameUserString dc_occ_nm
945 is_infix = isDataSymOcc dc_occ_nm
949 | is_infix = mk_showString_app (' ':dc_occ_nm_str)
950 | otherwise = mk_showString_app (dc_occ_nm_str ++ space_ocurly_maybe)
954 | lab_fields == 0 = " "
958 show_all con fs@(x:xs)
959 | is_infix = x:con:xs
963 | lab_fields > 0 = [mk_showString_app "}"]
966 con:fs ++ ccurly_maybe
968 show_thingies = show_all show_con real_show_thingies_with_labs
970 show_label l = mk_showString_app (the_name ++ "=")
972 occ_nm = getOccName (fieldLabelName l)
974 is_op = isSymOcc occ_nm
976 | is_op = '(':nm ++ ")"
979 nm = occNameUserString occ_nm
982 mk_showString_app str = HsApp (HsVar showString_RDR)
983 (HsLit (mkHsString str))
985 prec_cons = getLRPrecs is_infix get_fixity dc_nm
989 [ HsApp (HsApp (HsVar showsPrec_RDR) (HsLit (HsInt p))) (HsVar b)
990 | (p,b) <- zip prec_cons bs_needed ]
992 [ HsApp (HsApp (HsVar showsPrec_RDR) (HsLit (HsInt 10))) (HsVar b)
995 real_show_thingies_with_labs
996 | lab_fields == 0 = intersperse (HsVar showSpace_RDR) real_show_thingies
997 | otherwise = --Assumption: no of fields == no of labelled fields
998 -- (and in same order)
1000 intersperse ([mk_showString_app ","]) $ -- Using SLIT()s containing ,s spells trouble.
1001 zipWithEqual "gen_Show_binds"
1003 (map show_label labels)
1007 c.f. Figure 16 and 17 in Haskell 1.1 report
1010 | not is_infix = defaultPrecedence + 1
1011 | otherwise = getPrecedence get_fixity dc_nm + 1
1016 getLRPrecs :: Bool -> FixityEnv -> Name -> [Integer]
1017 getLRPrecs is_infix get_fixity nm = [lp, rp]
1020 Figuring out the fixities of the arguments to a constructor,
1021 cf. Figures 16-18 in Haskell 1.1 report.
1023 (con_left_assoc, con_right_assoc) = isLRAssoc get_fixity nm
1024 paren_con_prec = getPrecedence get_fixity nm
1027 | not is_infix = defaultPrecedence + 1
1028 | con_left_assoc = paren_con_prec
1029 | otherwise = paren_con_prec + 1
1032 | not is_infix = defaultPrecedence + 1
1033 | con_right_assoc = paren_con_prec
1034 | otherwise = paren_con_prec + 1
1036 defaultPrecedence :: Integer
1037 defaultPrecedence = fromInt maxPrecedence
1039 getPrecedence :: FixityEnv -> Name -> Integer
1040 getPrecedence get_fixity nm
1041 = case lookupFixity get_fixity nm of
1042 Fixity x _ -> fromInt x
1044 isLRAssoc :: FixityEnv -> Name -> (Bool, Bool)
1045 isLRAssoc get_fixity nm =
1046 case lookupFixity get_fixity nm of
1047 Fixity _ InfixN -> (False, False)
1048 Fixity _ InfixR -> (False, True)
1049 Fixity _ InfixL -> (True, False)
1053 %************************************************************************
1055 \subsection{Generating extra binds (@con2tag@ and @tag2con@)}
1057 %************************************************************************
1062 con2tag_Foo :: Foo ... -> Int#
1063 tag2con_Foo :: Int -> Foo ... -- easier if Int, not Int#
1064 maxtag_Foo :: Int -- ditto (NB: not unlifted)
1067 The `tags' here start at zero, hence the @fIRST_TAG@ (currently one)
1072 = GenCon2Tag | GenTag2Con | GenMaxTag
1074 gen_tag_n_con_monobind
1075 :: (RdrName, -- (proto)Name for the thing in question
1076 TyCon, -- tycon in question
1080 gen_tag_n_con_monobind (rdr_name, tycon, GenCon2Tag)
1081 | lots_of_constructors
1082 = mk_FunMonoBind (getSrcLoc tycon) rdr_name
1083 [([VarPatIn a_RDR], HsApp getTag_Expr a_Expr)]
1086 = mk_FunMonoBind (getSrcLoc tycon) rdr_name (map mk_stuff (tyConDataCons tycon))
1089 lots_of_constructors = tyConFamilySize tycon > mAX_FAMILY_SIZE_FOR_VEC_RETURNS
1091 mk_stuff :: DataCon -> ([RdrNamePat], RdrNameHsExpr)
1093 = ([pat], HsLit (HsIntPrim (toInteger ((dataConTag var) - fIRST_TAG))))
1095 pat = ConPatIn var_RDR (nOfThem (dataConSourceArity var) WildPatIn)
1096 var_RDR = qual_orig_name var
1098 gen_tag_n_con_monobind (rdr_name, tycon, GenTag2Con)
1099 = mk_FunMonoBind (getSrcLoc tycon) rdr_name
1100 [([ConPatIn mkInt_RDR [VarPatIn a_RDR]],
1101 ExprWithTySig (HsApp tagToEnum_Expr a_Expr)
1102 (HsTyVar (qual_orig_name tycon)))]
1104 gen_tag_n_con_monobind (rdr_name, tycon, GenMaxTag)
1105 = mk_easy_FunMonoBind (getSrcLoc tycon)
1106 rdr_name [] [] (HsApp (HsVar mkInt_RDR) (HsLit (HsIntPrim max_tag)))
1108 max_tag = case (tyConDataCons tycon) of
1109 data_cons -> toInteger ((length data_cons) - fIRST_TAG)
1113 %************************************************************************
1115 \subsection{Utility bits for generating bindings}
1117 %************************************************************************
1119 @mk_easy_FunMonoBind fun pats binds expr@ generates:
1121 fun pat1 pat2 ... patN = expr where binds
1124 @mk_FunMonoBind fun [([p1a, p1b, ...], e1), ...]@ is for
1125 multi-clause definitions; it generates:
1127 fun p1a p1b ... p1N = e1
1128 fun p2a p2b ... p2N = e2
1130 fun pMa pMb ... pMN = eM
1134 mk_easy_FunMonoBind :: SrcLoc -> RdrName -> [RdrNamePat]
1135 -> [RdrNameMonoBinds] -> RdrNameHsExpr
1138 mk_easy_FunMonoBind loc fun pats binds expr
1139 = FunMonoBind fun False{-not infix-} [mk_easy_Match loc pats binds expr] loc
1141 mk_easy_Match loc pats binds expr
1142 = mk_match loc pats expr (mkMonoBind (andMonoBindList binds) [] Recursive)
1143 -- The renamer expects everything in its input to be a
1144 -- "recursive" MonoBinds, and it is its job to sort things out
1147 mk_FunMonoBind :: SrcLoc -> RdrName
1148 -> [([RdrNamePat], RdrNameHsExpr)]
1151 mk_FunMonoBind loc fun [] = panic "TcGenDeriv:mk_FunMonoBind"
1152 mk_FunMonoBind loc fun pats_and_exprs
1153 = FunMonoBind fun False{-not infix-}
1154 [ mk_match loc p e EmptyBinds | (p,e) <-pats_and_exprs ]
1157 mk_match loc pats expr binds
1158 = Match (map paren pats) Nothing
1159 (GRHSs (unguardedRHS expr loc) binds placeHolderType)
1161 paren p@(VarPatIn _) = p
1162 paren other_p = ParPatIn other_p
1166 mk_easy_App f xs = foldl HsApp (HsVar f) (map HsVar xs)
1169 ToDo: Better SrcLocs.
1174 -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1175 -> RdrNameHsExpr -> RdrNameHsExpr
1177 careful_compare_Case :: -- checks for primitive types...
1179 -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1180 -> RdrNameHsExpr -> RdrNameHsExpr
1183 cmp_eq_Expr a b = HsApp (HsApp (HsVar cmp_eq_RDR) a) b
1184 -- Was: compare_gen_Case cmp_eq_RDR
1186 compare_gen_Case fun lt eq gt a b
1187 = HsCase (HsPar (HsApp (HsApp (HsVar fun) a) b)) {-of-}
1188 [mkSimpleMatch [ConPatIn ltTag_RDR []] lt placeHolderType generatedSrcLoc,
1189 mkSimpleMatch [ConPatIn eqTag_RDR []] eq placeHolderType generatedSrcLoc,
1190 mkSimpleMatch [ConPatIn gtTag_RDR []] gt placeHolderType generatedSrcLoc]
1193 careful_compare_Case ty lt eq gt a b
1194 | not (isUnLiftedType ty) =
1195 compare_gen_Case compare_RDR lt eq gt a b
1197 -- we have to do something special for primitive things...
1198 HsIf (genOpApp a relevant_eq_op b)
1200 (HsIf (genOpApp a relevant_lt_op b) lt gt generatedSrcLoc)
1203 relevant_eq_op = assoc_ty_id eq_op_tbl ty
1204 relevant_lt_op = assoc_ty_id lt_op_tbl ty
1206 assoc_ty_id tyids ty
1207 = if null res then panic "assoc_ty"
1210 res = [id | (ty',id) <- tyids, ty `tcEqType` ty']
1213 [(charPrimTy, eqH_Char_RDR)
1214 ,(intPrimTy, eqH_Int_RDR)
1215 ,(wordPrimTy, eqH_Word_RDR)
1216 ,(addrPrimTy, eqH_Addr_RDR)
1217 ,(floatPrimTy, eqH_Float_RDR)
1218 ,(doublePrimTy, eqH_Double_RDR)
1222 [(charPrimTy, ltH_Char_RDR)
1223 ,(intPrimTy, ltH_Int_RDR)
1224 ,(wordPrimTy, ltH_Word_RDR)
1225 ,(addrPrimTy, ltH_Addr_RDR)
1226 ,(floatPrimTy, ltH_Float_RDR)
1227 ,(doublePrimTy, ltH_Double_RDR)
1230 -----------------------------------------------------------------------
1232 and_Expr, append_Expr :: RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1234 and_Expr a b = genOpApp a and_RDR b
1235 append_Expr a b = genOpApp a append_RDR b
1237 -----------------------------------------------------------------------
1239 eq_Expr :: Type -> RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1240 eq_Expr ty a b = genOpApp a eq_op b
1243 | not (isUnLiftedType ty) = eq_RDR
1245 -- we have to do something special for primitive things...
1246 assoc_ty_id eq_op_tbl ty
1251 untag_Expr :: TyCon -> [(RdrName, RdrName)] -> RdrNameHsExpr -> RdrNameHsExpr
1252 untag_Expr tycon [] expr = expr
1253 untag_Expr tycon ((untag_this, put_tag_here) : more) expr
1254 = HsCase (HsPar (HsApp (con2tag_Expr tycon) (HsVar untag_this))) {-of-}
1255 [mkSimpleMatch [VarPatIn put_tag_here] (untag_Expr tycon more expr) placeHolderType generatedSrcLoc]
1258 cmp_tags_Expr :: RdrName -- Comparison op
1259 -> RdrName -> RdrName -- Things to compare
1260 -> RdrNameHsExpr -- What to return if true
1261 -> RdrNameHsExpr -- What to return if false
1264 cmp_tags_Expr op a b true_case false_case
1265 = HsIf (genOpApp (HsVar a) op (HsVar b)) true_case false_case generatedSrcLoc
1268 :: RdrNameHsExpr -> RdrNameHsExpr
1270 enum_from_then_to_Expr
1271 :: RdrNameHsExpr -> RdrNameHsExpr -> RdrNameHsExpr
1274 enum_from_to_Expr f t2 = HsApp (HsApp (HsVar enumFromTo_RDR) f) t2
1275 enum_from_then_to_Expr f t t2 = HsApp (HsApp (HsApp (HsVar enumFromThenTo_RDR) f) t) t2
1277 showParen_Expr, readParen_Expr
1278 :: RdrNameHsExpr -> RdrNameHsExpr
1281 showParen_Expr e1 e2 = HsApp (HsApp (HsVar showParen_RDR) e1) e2
1282 readParen_Expr e1 e2 = HsApp (HsApp (HsVar readParen_RDR) e1) e2
1284 nested_compose_Expr :: [RdrNameHsExpr] -> RdrNameHsExpr
1286 nested_compose_Expr [e] = parenify e
1287 nested_compose_Expr (e:es)
1288 = HsApp (HsApp (HsVar compose_RDR) (parenify e)) (nested_compose_Expr es)
1290 -- impossible_Expr is used in case RHSs that should never happen.
1291 -- We generate these to keep the desugarer from complaining that they *might* happen!
1292 impossible_Expr = HsApp (HsVar error_RDR) (HsLit (HsString (_PK_ "Urk! in TcGenDeriv")))
1294 -- illegal_Expr is used when signalling error conditions in the RHS of a derived
1295 -- method. It is currently only used by Enum.{succ,pred}
1296 illegal_Expr meth tp msg =
1297 HsApp (HsVar error_RDR) (HsLit (HsString (_PK_ (meth ++ '{':tp ++ "}: " ++ msg))))
1299 -- illegal_toEnum_tag is an extended version of illegal_Expr, which also allows you
1300 -- to include the value of a_RDR in the error string.
1301 illegal_toEnum_tag tp maxtag =
1302 HsApp (HsVar error_RDR)
1303 (HsApp (HsApp (HsVar append_RDR)
1304 (HsLit (HsString (_PK_ ("toEnum{" ++ tp ++ "}: tag (")))))
1305 (HsApp (HsApp (HsApp
1306 (HsVar showsPrec_RDR)
1311 (HsLit (HsString (_PK_ ") is outside of enumeration's range (0,"))))
1312 (HsApp (HsApp (HsApp
1313 (HsVar showsPrec_RDR)
1316 (HsLit (HsString (_PK_ ")")))))))
1318 parenify e@(HsVar _) = e
1319 parenify e = HsPar e
1321 -- genOpApp wraps brackets round the operator application, so that the
1322 -- renamer won't subsequently try to re-associate it.
1323 -- For some reason the renamer doesn't reassociate it right, and I can't
1324 -- be bothered to find out why just now.
1326 genOpApp e1 op e2 = mkHsOpApp e1 op e2
1330 qual_orig_name n = nameRdrName (getName n)
1331 varUnqual n = mkUnqual varName n
1333 zz_a_RDR = varUnqual SLIT("_a")
1334 a_RDR = varUnqual SLIT("a")
1335 b_RDR = varUnqual SLIT("b")
1336 c_RDR = varUnqual SLIT("c")
1337 d_RDR = varUnqual SLIT("d")
1338 ah_RDR = varUnqual SLIT("a#")
1339 bh_RDR = varUnqual SLIT("b#")
1340 ch_RDR = varUnqual SLIT("c#")
1341 dh_RDR = varUnqual SLIT("d#")
1342 cmp_eq_RDR = varUnqual SLIT("cmp_eq")
1343 rangeSize_RDR = varUnqual SLIT("rangeSize")
1345 as_RDRs = [ varUnqual (_PK_ ("a"++show i)) | i <- [(1::Int) .. ] ]
1346 bs_RDRs = [ varUnqual (_PK_ ("b"++show i)) | i <- [(1::Int) .. ] ]
1347 cs_RDRs = [ varUnqual (_PK_ ("c"++show i)) | i <- [(1::Int) .. ] ]
1349 mkHsString s = HsString (_PK_ s)
1351 zz_a_Expr = HsVar zz_a_RDR
1352 a_Expr = HsVar a_RDR
1353 b_Expr = HsVar b_RDR
1354 c_Expr = HsVar c_RDR
1355 d_Expr = HsVar d_RDR
1356 ltTag_Expr = HsVar ltTag_RDR
1357 eqTag_Expr = HsVar eqTag_RDR
1358 gtTag_Expr = HsVar gtTag_RDR
1359 false_Expr = HsVar false_RDR
1360 true_Expr = HsVar true_RDR
1362 getTag_Expr = HsVar getTag_RDR
1363 tagToEnum_Expr = HsVar tagToEnumH_RDR
1364 con2tag_Expr tycon = HsVar (con2tag_RDR tycon)
1367 zz_a_Pat = VarPatIn zz_a_RDR
1368 a_Pat = VarPatIn a_RDR
1369 b_Pat = VarPatIn b_RDR
1370 c_Pat = VarPatIn c_RDR
1371 d_Pat = VarPatIn d_RDR
1373 con2tag_RDR, tag2con_RDR, maxtag_RDR :: TyCon -> RdrName
1375 con2tag_RDR tycon = varUnqual (_PK_ ("con2tag_" ++ occNameString (getOccName tycon) ++ "#"))
1376 tag2con_RDR tycon = varUnqual (_PK_ ("tag2con_" ++ occNameString (getOccName tycon) ++ "#"))
1377 maxtag_RDR tycon = varUnqual (_PK_ ("maxtag_" ++ occNameString (getOccName tycon) ++ "#"))