হাস্কেল সাবসেট → সে - 18926 টি অক্ষর
এটি হাস্কেল থেকে সি এর একটি ছোট উপসেট সংকলন করে বৈশিষ্ট্যগুলি যা এটি সমর্থন করে:
- প্যাটার্ন ম্যাচিং এবং গার্ডস
- ডেটা ঘোষণা
- ইনফিক্স অপারেটর নির্বাচন করুন
- অলস মূল্যায়ন
বৃহত্তম অনুপস্থিত বৈশিষ্ট্যগুলি হ'ল নেস্টেড ভেরিয়েবল (যার অর্থ ল্যাম্বডা / লেট / যেখানে / কেস নয়), টাইপ চেকিং এবং টাইপ ক্লাস। ফলাফলগুলির প্রোগ্রামগুলি মেমরি ফাঁস করে দেয় এবং স্ব-সংকলনটি আমার সিস্টেমে প্রায় 200 মেগাবাইট লাগে ( বোহম আবর্জনা সংগ্রহকারী অনেক সাহায্য করে, তবে কেবল সংকলক পুচ্ছ পুনরাবৃত্তিটি সর্বোত্তমভাবে অনুকূলিত করলে)।
বুটস্ট্র্যাপ করার জন্য, প্রথম তিনটি লাইন (স্কোরের মধ্যে গণনা করা হয়নি) কে সংশোধন করুন এবং জিএইচসি দিয়ে সংকলন করুন। সংকলকটি স্ট্ডিনে হাস্কেল-সাবসেট কোড নেয় এবং স্টডআউটে সি কোড তৈরি করে।
ভাষা জটিল হওয়ার কারণে এটি দীর্ঘ নয়, তবে আমি অলসতার কারণে। তবে এটি বর্তমানে সংক্ষিপ্ত সমাধানটি আর নয়। অনুমান আমি এই সপ্তাহান্তে বিরক্ত হবে না।
-- import Prelude hiding (fmap, lookup, snd, zip);import Data.Char
-- import Data.List hiding (lookup, zip);data P a b = P a b;data B = B
-- add=(+);sub=(-);showInt=show;append[]ys=ys;append(x:xs)ys=x:append xs ys
data Program = Program [[Constructor]] [Function]
data Toplevel = TD [Constructor] | TE Equation | TO
data Constructor = Constructor String Int
data Function = Function String Int [Equation]
data Equation = Equation String [Pattern] (Maybe Expression) Expression
data Pattern = PVar String | PCon String [Pattern]
data Expression = Var String | Con String | Int String | Char String | String String | Ap Expression Expression
data Environment = Environment [P String Int] [P String VarInfo]
data VarInfo = VBox String | VArg Int | VItem VarInfo Int
main = interact (compile . parse)
constructorName (Constructor name _) = name
functionName (Function name _ _) = name
equationName (Equation name _ _ _) = name
sortToplevels [] = (P [] [])
sortToplevels (TD x : xs) = applyFst ((:) x) (sortToplevels xs)
sortToplevels (TE x : xs) = applySnd ((:) x) (sortToplevels xs)
sortToplevels (TO : xs) = sortToplevels xs
pcons x xs = PCon "Cons" [x, xs];pnil = PCon "Nil" []
ebinary op a b = Ap (Ap (Var op) a) b;ebinaryE op a b = Ap (Ap op a) b
econs x xs = Ap (Ap (Con "Cons") x) xs
enil = Con "Nil"
listEq eq [] [] = True
listEq eq (x:xs) (y:ys) | eq x y = listEq eq xs ys
listEq _ _ _ = False
snd (P a b) = b
zip = zipWith P
lookup q (P k v : _) | listEq (==) q k = Just v
lookup q (_ : xs) = lookup q xs
lookup q _ = Nothing
compose2 f g x y = f (g x y)
applyFst f (P x y) = P (f x) y
applySnd f (P x y) = P x (f y)
fMaybe f Nothing = Nothing
fMaybe f (Just x) = Just (f x)
cond f t False = f
cond f t True = t
condList f t [] = f
condList f t xs = t xs
countFrom n = n : countFrom (add n 1)
range l h | l > h = []
range l h = l : range (add l 1) h
parse = makeProgram . sortToplevels . concatMap parse_p . ((:) prelude) . preprocess
parse_p (P lineno line) = maybe (parse_err lineno line) snd (parseLine line)
parse_err lineno line = error (concat ["Parse error on line ", showInt lineno, ": `", line, "`"])
preprocess = filter (not . isCommentOrEmpty . snd) . zip (countFrom 1) . map (dropWhile isBlank) . lines
isCommentOrEmpty = parserSucceeds (pro (ignore (pro (parseS "--") (parseS "import "))) parseEof)
liftA2 f a b = ap (fmap f a) b
parserSucceeds p s = maybe False (const True) (p s)
fmap f p = fMaybe (applySnd f) . p
pure x s = Just (P s x)
ap1 b (P s x) = maybe Nothing (ap2 x) (b s)
ap2 x (P s y) = Just (P s (x y))
empty = (const Nothing)
pro a b s = maybe (b s) Just (a s)
ap a b = maybe Nothing (ap1 b) . a
prc = liftA2 (:)
pra = liftA2 append
prl = liftA2 const
prr = liftA2 (const id)
many p = pro (some p) (pure [])
some p = prc p (many p)
optional p = pro (fmap Just p) (pure Nothing)
choice = foldr pro (const Nothing)
parseEof = parseEof_1
parseEof_1 [] = Just (P "" B)
parseEof_1 _ = Nothing
parsePred pred = parsePred_1 pred
parsePred_1 pred (x:xs) | pred x = Just (P xs x)
parsePred_1 _ _ = Nothing
manyParsePred = justFlipSplit
justFlipSplit pred xs = Just (P (dropWhile pred xs) (takeWhile pred xs))
someParsePred pred = prc (parsePred pred) (manyParsePred pred)
parseC = parsePred . (==)
parseS = foldr (prc . parseC) (pure [])
wrapC = wrapSpace . parseC
wrapS = wrapSpace . parseS
skipPred pred = prr (parsePred pred) (pure B)
manySkipPred pred = prr (manyParsePred pred) (pure B)
preSep p sep = many (prr sep p)
sepBy1 p sep = prc p (many (prr sep p))
sepByChar p c = pro (sepByChar1 p c) (pure [])
sepByChar1 p c = sepBy1 p (wrapSpace (parseC c))
wrapSpace p = prl (prr skipSpace p) skipSpace
ignore = fmap (const B)
isBlank c | c == ' ' || c == '\t' = True
isBlank _ = False
isDigit1 c = c >= '1' && c <= '9'
parseBetween l r p = prl (prr (parseC l) (wrapSpace p)) (parseC r)
skipSpace = manySkipPred isBlank
chainl1 f sep p = fmap (foldl1 f) (sepBy1 p sep)
chainr1 f sep p = fmap (foldr1 f) (sepBy1 p sep)
chainl f z sep p = pro (fmap (foldl f z) (sepBy1 p sep)) (pure z)
chainr f z sep p = pro (fmap (foldr f z) (sepBy1 p sep)) (pure z)
parseNonassoc ops term = liftA2 (flip ($)) term (pro (liftA2 flip (choice ops) term) (pure id))
parseVar = prc (parsePred (orUnderscore isLower)) (many (parsePred (orUnderscore isAlphaNum)))
orUnderscore p c | p c || c == '_' = True
orUnderscore _ _ = False
parseCon = prc (parsePred isUpper) (many (parsePred (orUnderscore isAlphaNum)))
parseInt = pro (parseS "0") (prc (parsePred isDigit1) (many (parsePred isDigit)))
parseEscape q (c:x:xs) | c == '\\' = Just (P xs (c:x:[]))
parseEscape q [c] | c == '\\' = Just (P [] [c])
parseEscape q (c:xs) | c /= q = Just (P xs [c])
parseEscape q _ = Nothing
parseStringLiteral q = pra (parseS [q]) (pra (fmap concat (many (parseEscape q))) (parseS [q]))
parsePattern = chainr1 pcons (wrapC ':') (pro (liftA2 PCon parseCon (preSep parsePatternPrimary skipSpace)) parsePatternPrimary)
parsePatternPrimary = choice [fmap PVar parseVar, fmap (flip PCon []) parseCon, parseBetween '(' ')' parsePattern, parseBetween '[' ']' (fmap (foldr pcons pnil) (sepByChar parsePattern ','))]
relops f = relops_1 (ops_c f)
otherops f = f ":" (Con "Cons") : otherops_1 (ops_c f)
ops_c f x y = f x (Var y)
relops_1 f = [f "<=" "_le", f "<" "_lt", f "==" "_eq", f ">=" "_ge", f ">" "_gt", f "/=" "_ne"]
otherops_1 f = [f "$" "_apply", f "||" "_or", f "&&" "_and", f "." "_compose"]
parseRelops = parseNonassoc (relops parseRelops_f)
parseRelops_f op func = prr (wrapS op) (pure (ebinaryE func))
parseExpression = chainr1 (ebinary "_apply") (wrapC '$') $ chainr1 (ebinary "_or") (wrapS "||") $ chainr1 (ebinary "_and") (wrapS "&&") $ parseRelops $ chainr1 econs (wrapC ':') $ chainr1 (ebinary "_compose") (wrapC '.') $ chainl1 Ap skipSpace $ choice [fmap Var parseVar, fmap Con parseCon, fmap Int parseInt, fmap Char (parseStringLiteral '\''), fmap String (parseStringLiteral '"'), parseBetween '(' ')' (pro parseSection parseExpression), parseBetween '[' ']' (chainr econs enil (wrapC ',') parseExpression)]
parseSection = choice (append (relops parseSection_f) (otherops parseSection_f))
parseSection_f op func = prr (wrapS op) (pure func)
parseEquation = ap (ap (ap (fmap Equation parseVar) (many (prr skipSpace parsePatternPrimary))) (optional (prr (wrapC '|') parseExpression))) (prr (wrapC '=') parseExpression)
skipType = ignore (sepBy1 (sepBy1 skipTypePrimary skipSpace) (wrapS "->"))
skipTypePrimary = choice [ignore parseVar, ignore parseCon, parseBetween '(' ')' skipType, parseBetween '[' ']' skipType]
parseDataDecl = prr (parseS "data") (prr skipSpace (prr parseCon (prr (preSep parseVar skipSpace) (prr (wrapC '=') (sepByChar1 (liftA2 Constructor parseCon (fmap length (preSep skipTypePrimary skipSpace))) '|')))))
skipTypeSignature = prr parseVar (prr (wrapS "::") skipType)
skipTypeAlias = prr (parseS "type") (prr skipSpace (prr parseCon (prr (preSep parseVar skipSpace) (prr (wrapC '=') skipType))))
parseToplevel = choice [fmap (const TO) (pro skipTypeSignature skipTypeAlias), fmap TD parseDataDecl, fmap TE parseEquation]
parseLine = prl (prl (sepByChar1 parseToplevel ';') skipSpace) parseEof
patternCount (Equation _ ps _ _) = length ps
makeProgram (P ds es) = Program ds (makeFunctions es)
makeFunctions = map makeFunctions_f . groupBy makeFunctions_g
makeFunctions_f [] = error "Internal error: No equations in binding group"
makeFunctions_f (x:xs) = cond (error (concat ["Equations for ", equationName x, " have different numbers of arguments"])) (Function (equationName x) (patternCount x) (x:xs)) (all (((==) (patternCount x)) . patternCount) xs)
makeFunctions_g (Equation name_a _ _ _) (Equation name_b _ _ _) = listEq (==) name_a name_b
lookupCon name (Environment c _) = lookup name c
lookupVar name (Environment _ v) = lookup name v
walkPatterns f = walkPatterns_items f VArg
walkPatterns_items f base = concat . zipWith (walkPatterns_f2 f) (map base (countFrom 0))
walkPatterns_f2 f v (PCon name ps) = append (f v (PCon name ps)) (walkPatterns_items f (VItem v) ps)
walkPatterns_f2 f v p = f v p
compile (Program decls funcs) = concat [header, declareConstructors decls, declareFunctions funcs, boxConstructors decls, boxFunctions funcs, compileConstructors decls, compileFunctions (globalEnv decls funcs) funcs]
globalEnv decls funcs = Environment (append (globalEnv_constructorTags decls) (globalEnv_builtinConstructors)) (append (map (globalEnv_f . functionName) funcs) globalEnv_builtinFunctions)
globalEnv_f name = (P name (VBox name))
globalEnv_constructorTags = concatMap (flip zip (countFrom 0) . map constructorName)
globalEnv_builtinConstructors = [P "Nil" 0, P "Cons" 1, P "P" 0]
globalEnv_builtinFunctions = map globalEnv_f ["add", "sub", "_lt", "_le", "_eq", "_ge", "_gt", "_ne", "_and", "_or", "divMod", "negate", "not", "error"]
localEnv ps (Environment t v) = Environment t (append (walkPatterns localEnv_f ps) v)
localEnv_f v (PVar name) = [P name v]
localEnv_f _ (PCon _ _) = []
declareFunctions_f [] = ""
declareFunctions_f xs = concat ["static Function ", intercalate ", " xs, ";\n"]
declareConstructors = declareFunctions_f . map ((append "f_") . constructorName) . concat
declareFunctions = declareFunctions_f . map ((append "f_") . functionName)
boxConstructors = concatMap boxConstructors_f . concat
boxConstructors_f (Constructor name n) = boxThing name n
boxFunctions = concatMap boxFunctions_f
boxFunctions_f (Function name n _) = boxThing name n
boxThing name n | n == 0 = concat ["static Box b_", name, " = {0, f_", name, ", NULL};\n"]
boxThing name n = concat ["static Partial p_", name, " = {", showInt n, ", 0, f_", name, "};\n", "static Box b_", name, " = {1, NULL, &p_", name, "};\n"]
compileConstructors = concatMap (concat . zipWith compileConstructors_f (countFrom 0))
compileConstructors_f tag (Constructor name n) = concat ["static void *f_", name, "(Box **args)\n", "{\n", allocate n, "\tv->tag = ", showInt tag, ";\n", concatMap initialize (range 0 (sub n 1)), "\treturn v;\n", "}\n"]
allocate n | n == 0 = "\tValue *v = malloc(sizeof(Value));\n\t(void) args;\n"
allocate n = concat ["\tValue *v = malloc(sizeof(Value) + ", showInt n, " * sizeof(Box*));\n"]
initialize i = concat ["\tv->items[", showInt i, "] = args[", showInt i, "];\n"]
compileFunctions env = concatMap (compileFunction env)
compileFunction env (Function name argc equations) = concat ["static void *f_", name, "(Box **args)\n", "{\n", concatMap (compileEquation env) equations, "\tNO_MATCH(", name, ");\n", "}\n"]
compileEquation genv (Equation _ patterns guard expr) = compileEquation_a (localEnv patterns genv) patterns guard expr
compileEquation_a env patterns guard expr = compileEquation_b (concat ["\treturn ", compileExpressionStrict env expr, ";\n"]) (append (compilePatterns env patterns) (compileGuard env guard))
compileEquation_b returnExpr preds = condList returnExpr (compileEquation_f returnExpr) preds
compileEquation_f returnExpr xs = concat ["\tif (", intercalate " && " xs, ")\n\t", returnExpr]
compilePatterns env = walkPatterns (compilePatterns_f env)
compilePatterns_f _ _ (PVar name) = []
compilePatterns_f env v (PCon name ps) = compilePatterns_h v name (lookupCon name env)
compilePatterns_h v name (Just n) = [concat ["match(", compileVarInfo v, ",", showInt n, ")"]]
compilePatterns_h v name Nothing = error (append "Not in scope: data constructor " name)
compileGuard env Nothing = []
compileGuard env (Just expr) = [concat ["isTrue(", compileExpressionStrict env expr, ")"]]
compileExpressionStrict env (Var name) = concat ["force(", compileVar (lookupVar name env) name, ")"]
compileExpressionStrict _ (Con name) = concat ["force(&b_", name, ")"]
compileExpressionStrict _ (Int s) = concat ["mkInt(", s, ")"]
compileExpressionStrict _ (Char s) = concat ["mkInt(", s, ")"]
compileExpressionStrict _ (String s) = concat ["mkString(", s, ")"]
compileExpressionStrict env (Ap f x) = concat ["apply(", compileExpressionStrict env f, ",", compileExpressionLazy env x, ")"]
compileExpressionLazy env (Var name) = compileVar (lookupVar name env) name
compileExpressionLazy _ (Con name) = concat ["&b_", name, ""]
compileExpressionLazy _ (Int s) = concat ["box(mkInt(", s, "))"]
compileExpressionLazy _ (Char s) = concat ["box(mkInt(", s, "))"]
compileExpressionLazy _ (String s) = concat ["box(mkString(", s, "))"]
compileExpressionLazy env (Ap f x) = concat ["deferApply(", compileExpressionLazy env f, ",", compileExpressionLazy env x, ")"]
compileVar (Just v) _ = compileVarInfo v
compileVar Nothing name = error (append "Not in scope: " name)
compileVarInfo (VBox name) = append "&b_" name
compileVarInfo (VArg n) = concat ["args[", showInt n, "]"]
compileVarInfo (VItem v n) = concat ["item(", compileVarInfo v, ",", showInt n, ")"]
header="#include <assert.h>\n#include <stdarg.h>\n#include <stdio.h>\n#include <stdlib.h>\n#include <string.h>\ntypedef struct Box Box;\ntypedef struct Value Value;\ntypedef struct Partial Partial;\ntypedef void *Function(Box**);\nstruct Box{int state;Function *func;void*vc;Box*fx[];};\nstruct Value{int tag;Box *items[];};\nstruct Partial{int remaining;int applied;Function *func;Box *args[];};\n#define copy(...)memdup(&(__VA_ARGS__), sizeof(__VA_ARGS__))\n#define countof(...)(sizeof(__VA_ARGS__) / sizeof(*(__VA_ARGS__)))\n#define match(box, expectedTag)(((Value*)force(box))->tag == (expectedTag))\n#define item(box, n)(((Value*)(box)->vc)->items[n])\n#define isTrue(value)(!!*(int*)(value))\n#define NO_MATCH(func)fatal(\"Non-exhaustive patterns in function \" #func)\nstatic void fatal(const char *str){fprintf(stderr,\"*** Exception: %s\\n\", str);exit(EXIT_FAILURE);}\nstatic void *memdup(void *ptr, size_t size){void*ret=malloc(size);memcpy(ret,ptr,size);return ret;}\nstatic void *force(Box *box){switch(box->state){\ncase 0:box->state=2;box->vc=box->func(box->vc);box->state=1;\ncase 1:return box->vc;\ndefault:fatal(\"infinite loop\");}}\nstatic void *apply(Partial*f,Box*x){Partial*f2=malloc(sizeof(Partial)+(f->applied+1)*sizeof(Box*));\nmemcpy(f2->args,f->args,f->applied*sizeof(Box*));f2->args[f->applied]=x;\nif(f->remaining>1){f2->remaining=f->remaining-1;f2->applied=f->applied+1;f2->func=f->func;return f2;\n}else return f->func(f2->args);}\nstatic void*deferApply_cb(Box**a){return apply(force(a[0]),a[1]);}\nstatic Box*deferApply(Box*f,Box*x){\nBox*ret=malloc(sizeof(Box)+2*sizeof(Box*));\nret->state=0;\nret->func=deferApply_cb;\nret->vc=ret->fx;\nret->fx[0]=f;\nret->fx[1]=x;\nreturn ret;}\n\nstatic Box*defer(Function*func,void*ctx){\nBox*ret=malloc(sizeof(Box));\nret->state=0;\nret->func=func;\nret->vc=ctx;\nreturn ret;}\n\nstatic Box *box(void *value)\n{\n\tBox *ret = malloc(sizeof(Box));\n\tret->state = 1;\n\tret->func = NULL;\n\tret->vc = value;\n\treturn ret;\n}\n\nstatic int *mkInt(int n)\n{\n\tint *ret = malloc(sizeof(*ret));\n\t*ret = n;\n\treturn ret;\n}\n\nstatic Function f_Nil, f_Cons, f_P;\nstatic Box b_Nil, b_Cons, b_P, b_main;\n\n#define FUNCTION(name, argc) \\\n\tstatic Function f_##name; \\\n\tstatic Partial p_##name = {argc, 0, f_##name}; \\\n\tstatic Box b_##name = {1, NULL, &p_##name}; \\\n\tstatic void *f_##name(Box **args)\n\n#define intop(name, expr) \\\n\tFUNCTION(name, 2) \\\n\t{ \\\n\t\tint a = *(int*)force(args[0]); \\\n\t\tint b = *(int*)force(args[1]); \\\n\t\treturn mkInt(expr); \\\n\t}\n\n#define intop1(name, expr) \\\n\tFUNCTION(name, 1) \\\n\t{ \\\n\t\tint a = *(int*)force(args[0]); \\\n\t\treturn mkInt(expr); \\\n\t}\n\nintop(add, a + b)\nintop(sub, a - b)\n\nintop(_lt, a < b)\nintop(_le, a <= b)\nintop(_eq, a == b)\nintop(_ge, a >= b)\nintop(_gt, a > b)\nintop(_ne, a != b)\nintop(_and, a && b)\nintop(_or, a || b)\n\nintop1(negate, -a)\nintop1(not, !a)\n\nFUNCTION(divMod, 2)\n{\n\tint n = *(int*)force(args[0]);\n\tint d = *(int*)force(args[1]);\n\tint div = n / d;\n\tint mod = n % d;\n\t\n\tif ((mod < 0 && d > 0) || (mod > 0 && d < 0)) {\n\t\tdiv--;\n\t\tmod += d;\n\t}\n\t\n\tBox *pair[2] = {box(mkInt(div)), box(mkInt(mod))};\n\treturn f_P(pair);\n}\n\nstatic void *mkString(const char *str)\n{\n\tif (*str != '\\0') {\n\t\tBox *cons[2] =\n\t\t\t{box(mkInt(*str)), defer((Function*) mkString, (void*)(str + 1))};\n\t\treturn f_Cons(cons);\n\t} else {\n\t\treturn force(&b_Nil);\n\t}\n}\n\nstatic void putStr(Value *v, FILE *f)\n{\n\tif (v->tag == 1) {\n\t\tint c = *(int*)force(v->items[0]);\n\t\tputc(c, f);\n\t\tputStr(force(v->items[1]), f);\n\t}\n}\n\nFUNCTION(error, 1)\n{\n\tfflush(stdout);\n\tfputs(\"*** Exception: \", stderr);\n\tputStr(force(args[0]), stderr);\n\tputc('\\n', stderr);\n\texit(EXIT_FAILURE);\n}\n\nstruct mkStringFromFile\n{\n\tFILE *f;\n\tconst char *name;\n};\n\nstatic void *mkStringFromFile(struct mkStringFromFile *ctx)\n{\n\tint c = fgetc(ctx->f);\n\t\n\tif (c == EOF) {\n\t\tif (ferror(ctx->f))\n\t\t\tperror(ctx->name);\n\t\treturn force(&b_Nil);\n\t}\n\t\n\tBox *cons[2] = {box(mkInt(c)), defer((Function*) mkStringFromFile, ctx)};\n\treturn f_Cons(cons);\n}\n\nint main(void)\n{\n\tstruct mkStringFromFile c_in = {stdin, \"<stdin>\"};\n\tBox *b_in = defer((Function*) mkStringFromFile, copy(c_in));\n\tputStr(apply(force(&b_main), b_in), stdout);\n\treturn 0;\n}\n"
prelude = P 0 "_apply f x=f x;_compose f g x=f(g x);data List a=Nil|Cons a(List a);data P a b=P a b;data B=B;data Maybe a=Nothing|Just a;data Bool=False|True;id x=x;const x _=x;flip f x y=f y x;foldl f z[]=z;foldl f z(x:xs)=foldl f(f z x)xs;foldl1 f(x:xs)=foldl f x xs;foldl1 _[]=error\"foldl1: empty list\";foldr f z[]=z;foldr f z(x:xs)=f x(foldr f z xs);foldr1 f[x]=x;foldr1 f(x:xs)=f x(foldr1 f xs);foldr1 _[]=error\"foldr1: empty list\";map f[]=[];map f(x:xs)=f x:map f xs;filter p[]=[];filter p(x:xs)|p x=x:filter p xs;filter p(x:xs)=filter p xs;zipWith f(x:xs)(y:ys)=f x y:zipWith f xs ys;zipWith f _ _=[];append[]ys=ys;append(x:xs)ys=x:append xs ys;concat=foldr append[];concatMap f=concat.map f;length[]=0;length(_:l)=add 1(length l);take n _|n<=0=[];take _[]=[];take n(x:xs)=x:take(sub n 1)xs;takeWhile p[]=[];takeWhile p(x:xs)|p x=x:takeWhile p xs;takeWhile _ _=[];dropWhile p[]=[];dropWhile p(x:xs)|p x=dropWhile p xs;dropWhile p xs=xs;span p[]=P[][];span p(x:xs)|p x=span_1 x(span p xs);span p xs=P[]xs;span_1 x(P ys zs)=P(x:ys)zs;break p=span(not.p);reverse=foldl(flip(:))[];groupBy _[]=[];groupBy eq(x:xs)=groupBy_1 x eq(span(eq x)xs);groupBy_1 x eq(P ys zs)=(x:ys):groupBy eq zs;maybe n f Nothing=n;maybe n f(Just x)=f x;all p=foldr(&&)True.map p;intersperse _[]=[];intersperse _[x]=[x];intersperse sep(x:xs)=x:sep:intersperse sep xs;intercalate xs xss=concat(intersperse xs xss);isDigit c=c>='0'&&c<='9';isAlphaNum c=c>='0'&&c<='9'||c>='A'&&c<='Z'||c>='a'&&c<='z';isUpper c=c>='A'&&c<='Z';isLower c=c>='a'&&c<='z';showInt n|n<0='-':showInt(negate n);showInt n|n==0=\"0\";showInt n|n>0=reverse(map(add 48)(showInt_1 n));showInt_1 n|n==0=[];showInt_1 n=showInt_2(divMod n 10);showInt_2(P div mod)=mod:showInt_1 div;lines []=[];lines s=lines_1(break((==)'\\n')s);lines_1(P l[])=[l];lines_1(P l(_:s))=l:lines s;interact=id"