2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1994
4 \section[SimplHaskell]{Printing Core that looks like Haskell}
7 #include "HsVersions.h"
9 module SimplHaskell ( coreToHaskell ) where
15 import BasicLit ( BasicLit )
21 import AbsPrel ( PrimOp, nilDataCon, consDataCon )
25 coreToHaskell :: PlainCoreProgram -> String {- 0 -}
26 coreToHaskell binds = ("[Haskell:\n\n" ++ ppShow 80 (pprHaskFuns (transformCoreProg binds)) ++ "\n\n]\n")
30 data HaskFun = HaskFun Id [([HaskExp],HaskExp)]
33 = HaskVar Bool Id -- true of used many times
36 | HaskCon Id [HaskExp]
37 | HaskPrim PrimOp [HaskExp]
38 | HaskLam [HaskExp] HaskExp
39 | HaskApp HaskExp HaskExp
40 | HaskCase HaskExp [(HaskExp,HaskExp)]
41 | HaskIf HaskExp HaskExp HaskExp
42 | HaskLet [HaskFun] HaskExp
45 Here is where the fun begins, you transform Core into Haskell!
48 type InEnv = IdEnv HaskExp
49 type OutEnv = IdEnv (Int,Bool) -- number of times used, and if save to inline
52 mkHaskPatVar :: OutEnv -> Id -> HaskExp
53 mkHaskPatVar env id = case lookupIdEnv env id of
55 Just (n,_) -> HaskVar (n > 1) id
57 transformCoreProg :: PlainCoreProgram -> [HaskFun]
58 transformCoreProg prog = mergeCasesBindings funs
60 (_,_,funs) = transformCoreBindings nullIdEnv nullIdEnv prog
62 transformCoreBindings :: InEnv -> OutEnv -> [PlainCoreBinding] -> (InEnv,OutEnv,[HaskFun])
63 transformCoreBindings in_env out_env [bnd] = transformCoreBinding in_env out_env bnd
64 transformCoreBindings in_env out_env (bnd:bnds) = (in_env'',out_env',hask_bnd ++ hask_bnds)
66 (in_env',out_env',hask_bnd) = transformCoreBinding in_env out_env'' bnd
67 (in_env'',out_env'',hask_bnds) = transformCoreBindings in_env' out_env bnds
69 transformCoreBinding :: InEnv -> OutEnv -> PlainCoreBinding -> (InEnv,OutEnv,[HaskFun])
70 transformCoreBinding in_env out_env (CoNonRec v expr) = (in_env',out_env'',[HaskFun v rhs])
72 out_env'' = merge out_env out_env'
73 (out_env',rhs) = transformCoreRhs in_env expr
74 in_env' = in_env `growIdEnvList` [ (v,exp) | [([],exp)] <- [rhs], False ]
76 transformCoreBinding in_env out_env (CoRec bnds) = (in_env,out_env'',hask_bnds)
78 out_env'' = foldl merge out_env out_envs
79 (out_envs,hask_bnds) = unzip
80 [ (out_env',HaskFun v rhs) |
82 (out_env',rhs) <- [transformCoreRhs in_env exp]]
85 transformCoreRhs :: InEnv -> PlainCoreExpr -> (OutEnv,[([HaskExp],HaskExp)])
86 transformCoreRhs in_env exp = (out_env,[(vars',hask_exp)])
88 vars' = [ mkHaskPatVar out_env v | v <- vars ]
89 (vars,exp') = getLambdaVars exp
90 (out_env,hask_exp) = transformCoreExp in_env exp'
91 getLambdaVars (CoTyLam _ e) = getLambdaVars e
92 getLambdaVars (CoLam xs e) = (xs ++ xs',e')
93 where (xs',e') = getLambdaVars e
94 getLambdaVars e = ([],e)
96 transformCoreExp :: InEnv -> PlainCoreExpr -> (OutEnv,HaskExp)
97 transformCoreExp _ (CoVar v) = (unitIdEnv v (1,True),HaskVar False v) -- lookup Env ?
98 transformCoreExp _ (CoLit i) = (nullIdEnv,HaskLit i)
99 transformCoreExp in_env (CoCon i _ atoms) = (out_env,HaskCon i hask_exps)
101 (out_env,hask_exps) = transformCoreExps in_env (map atomToExpr atoms)
102 transformCoreExp in_env (CoPrim i _ atoms) = (out_env,HaskPrim i hask_exps)
104 (out_env,hask_exps) = transformCoreExps in_env (map atomToExpr atoms)
107 transformCoreExp in_env (CoLam args exp) = (out_env,HaskLam args' h_exp)
108 where -- modify the env !!!!!
109 args' = [ mkHaskPatVar out_env v | v <- args ]
110 (out_env,h_exp) = transformCoreExp in_env exp
111 transformCoreExp in_env (CoTyLam _ exp) = transformCoreExp in_env exp
112 transformCoreExp in_env (CoApp fun atom) = (merge o1 o2,HaskApp h_fun h_arg)
114 (o1,h_fun) = transformCoreExp in_env fun
115 (o2,h_arg) = transformCoreExp in_env (atomToExpr atom)
116 transformCoreExp in_env (CoTyApp fun _) = transformCoreExp in_env fun
117 transformCoreExp in_env (CoCase e alts) = (foldl merge o1 o2,HaskCase h_e h_alts)
119 (o1,h_e) = transformCoreExp in_env e
120 (o2,h_alts) = unzip [ (out_env,(pat,h_e)) | (out_env,pat,h_e) <- transformCoreAlts in_env alts ]
122 transformCoreExp in_env exp@(CoLet _ _) = (o1,HaskLet h_binds h_exp)
124 (binds,exp') = getLets exp
125 (in_env',o1,h_binds) = transformCoreBindings in_env o2 binds
126 (o2,h_exp) = transformCoreExp in_env' exp'
127 getLets (CoLet bind exp) = (bind:binds,exp')
128 where (binds,exp') = getLets exp
129 getLets exp = ([],exp)
131 transformCoreExp _ _ = (nullIdEnv,HaskWild)
133 transformCoreExps :: InEnv -> [PlainCoreExpr] -> (OutEnv,[HaskExp])
134 transformCoreExps _ [] = (nullIdEnv,[])
135 transformCoreExps in_env (e:es) = (merge o1 o2,h_e:hs_e)
137 (o1,h_e) = transformCoreExp in_env e
138 (o2,hs_e) = transformCoreExps in_env es
140 transformCoreAlts :: InEnv -> PlainCoreCaseAlternatives -> [(OutEnv,HaskExp,HaskExp)]
141 transformCoreAlts in_env (CoAlgAlts alts def) = map trans alts ++ mkdef def
143 trans (id,ids,e) = (o1,HaskCon id (map (mkHaskPatVar o1) ids),h_e)
145 (o1,h_e) = transformCoreExp in_env e
146 mkdef (CoBindDefault bnd e) = [(o1,mkHaskPatVar o1 bnd,h_e)]
148 (o1,h_e) = transformCoreExp in_env e
150 transformCoreAlts in_env (CoPrimAlts alts def) = map trans alts ++ mkdef def
152 trans (lit,e) = (o1,HaskLit lit,h_e)
154 (o1,h_e) = transformCoreExp in_env e
155 mkdef (CoBindDefault bnd e) = [(o1,mkHaskPatVar o1 bnd,h_e)]
157 (o1,h_e) = transformCoreExp in_env e
162 merge :: OutEnv -> OutEnv -> OutEnv
163 merge e1 e2 = combineIdEnvs fn e1 e2
165 fn (n,_) (m,_) = (n+m,False)
170 mergeCasesBindings = map mergeCasesFun
172 mergeCasesFun (HaskFun id rhss) = HaskFun id (concat (map mergeCasesRhs rhss))
174 mergeCasesRhs (pats,exp) = [(pats,exp)]
178 A x -> e1 , v ==> Branch v [ (A x,e1), (B y,e2) ]
180 NoBranches (case v of
185 --mergeCases :: HaskExp -> Set Id -> [(Id,HaskExp,HaskExp)]
186 --mergeCases _ _ = []
195 thenSH m k s = case m s of
197 thenSH_ m k s = case m s of
201 pprHaskFuns xs = ppAboves (map pprHaskFun xs)
203 pprHaskFun (HaskFun id stuff) =
205 ppSep [ ppCat ([ppr PprForUser id] ++ map (pprHaskExp True) pats),
206 ppNest 2 (ppCat [ppStr "=",pprHaskExp False rhs])]
207 | (pats,rhs) <- stuff]
209 pprHaskExp :: Bool -> HaskExp -> Pretty
210 pprHaskExp _ (HaskVar _ id) = ppr PprForUser id
211 pprHaskExp _ (HaskLit i) = ppr PprForUser i
212 pprHaskExp _ (HaskWild) = ppStr "_"
213 pprHaskExp True exp = ppBesides [ppLparen,pprHaskExp False exp,ppRparen]
214 pprHaskExp _ (HaskCon con []) | con == nilDataCon = ppStr "[]"
215 pprHaskExp _ (HaskCon con [e1,e2]) | con == consDataCon =
216 ppCat [pprHaskExp True e1,ppStr ":",pprHaskExp True e2]
217 pprHaskExp _ (HaskCon con exps) =
218 ppCat (ppr PprForUser con:map (pprHaskExp True) exps)
219 pprHaskExp _ (HaskPrim prim exps) =
220 ppCat (ppr PprForUser prim:map (pprHaskExp True) exps)
221 pprHaskExp _ app@(HaskLam xs e) = -- \ xs -> e
222 ppSep [ ppCat ([ppStr "\\"] ++ map (pprHaskExp True) xs),
223 ppNest 2 (ppCat [ppStr "->",pprHaskExp False e])]
224 pprHaskExp _ app@(HaskApp _ _) = pprHaskApp app
225 pprHaskExp _ (HaskCase e opts)
226 = ppAboves [ppCat [ppStr "case", pprHaskExp False e,ppStr "of"],
229 (ppSep [ppCat [pprHaskExp False pat,ppStr "->"],
230 ppNest 2 (pprHaskExp False exp)])
231 | (pat,exp) <- opts])]
232 pprHaskExp _ (HaskIf i t e) = ppAboves
233 [ppCat [ppStr "if",pprHaskExp False i],
234 ppCat [ppStr "then",pprHaskExp False t],
235 ppCat [ppStr "else",pprHaskExp False e]]
236 pprHaskExp _ (HaskLet binds e)
237 = ppAboves [ppStr "let",
238 ppNest 2 (pprHaskFuns binds),
239 ppCat [ppStr "in",ppNest 1 (pprHaskExp False e)]]
240 pprHaskExp _ _ = panic "pprHaskExp failed"
243 pprHaskApp (HaskApp fun arg) = ppCat [pprHaskApp fun,pprHaskExp True arg]
244 pprHaskApp e = pprHaskExp True e
249 pprHaskExp n exp = ppr