| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
GHC.Types.Literal
Synopsis
- data Literal
- data LitNumType
- mkLitInt :: Platform -> Integer -> Literal
- mkLitIntWrap :: Platform -> Integer -> Literal
- mkLitIntWrapC :: Platform -> Integer -> (Literal, Bool)
- mkLitIntUnchecked :: Integer -> Literal
- mkLitWord :: Platform -> Integer -> Literal
- mkLitWordWrap :: Platform -> Integer -> Literal
- mkLitWordWrapC :: Platform -> Integer -> (Literal, Bool)
- mkLitInt64 :: Integer -> Literal
- mkLitInt64Wrap :: Platform -> Integer -> Literal
- mkLitWord64 :: Integer -> Literal
- mkLitWord64Wrap :: Platform -> Integer -> Literal
- mkLitFloat :: Rational -> Literal
- mkLitDouble :: Rational -> Literal
- mkLitChar :: Char -> Literal
- mkLitString :: String -> Literal
- mkLitInteger :: Integer -> Literal
- mkLitNatural :: Integer -> Literal
- mkLitNumber :: Platform -> LitNumType -> Integer -> Literal
- mkLitNumberWrap :: Platform -> LitNumType -> Integer -> Literal
- literalType :: Literal -> Type
- absentLiteralOf :: TyCon -> Maybe Literal
- pprLiteral :: (SDoc -> SDoc) -> Literal -> SDoc
- litNumIsSigned :: LitNumType -> Bool
- litNumCheckRange :: Platform -> LitNumType -> Integer -> Bool
- litIsDupable :: Platform -> Literal -> Bool
- litIsTrivial :: Literal -> Bool
- litIsLifted :: Literal -> Bool
- inCharRange :: Char -> Bool
- isZeroLit :: Literal -> Bool
- litFitsInChar :: Literal -> Bool
- litValue :: Literal -> Integer
- isLitValue :: Literal -> Bool
- isLitValue_maybe :: Literal -> Maybe Integer
- mapLitValue :: Platform -> (Integer -> Integer) -> Literal -> Literal
- word2IntLit :: Platform -> Literal -> Literal
- int2WordLit :: Platform -> Literal -> Literal
- narrowLit :: forall a. Integral a => Proxy a -> Literal -> Literal
- narrow8IntLit :: Literal -> Literal
- narrow16IntLit :: Literal -> Literal
- narrow32IntLit :: Literal -> Literal
- narrow8WordLit :: Literal -> Literal
- narrow16WordLit :: Literal -> Literal
- narrow32WordLit :: Literal -> Literal
- char2IntLit :: Literal -> Literal
- int2CharLit :: Literal -> Literal
- float2IntLit :: Literal -> Literal
- int2FloatLit :: Literal -> Literal
- double2IntLit :: Literal -> Literal
- int2DoubleLit :: Literal -> Literal
- nullAddrLit :: Literal
- rubbishLit :: Literal
- float2DoubleLit :: Literal -> Literal
- double2FloatLit :: Literal -> Literal
Main data type
So-called Literals are one of:
- An unboxed numeric literal or floating-point literal which is presumed
to be surrounded by appropriate constructors (
Int#, etc.), so that the overall thing makes sense.
We maintain the invariant that the Integer in the LitNumber
constructor is actually in the (possibly target-dependent) range.
The mkLit{Int,Word}*Wrap smart constructors ensure this by applying
the target machine's wrapping semantics. Use these in situations
where you know the wrapping semantics are correct.
- The literal derived from the label mentioned in a "foreign label"
declaration (
LitLabel) - A
LitRubbishto be used in place of values ofUnliftedRep(i.e. 'MutVar#') when the value is never used. - A character
- A string
- The NULL pointer
Constructors
| LitChar Char |
|
| LitNumber !LitNumType !Integer | Any numeric literal that can be internally represented with an Integer. |
| LitString !ByteString | A string-literal: stored and emitted
UTF-8 encoded, we'll arrange to decode it
at runtime. Also emitted with a |
| LitNullAddr | The |
| LitRubbish | A nonsense value, used when an unlifted
binding is absent and has type
|
| LitFloat Rational |
|
| LitDouble Rational |
|
| LitLabel FastString (Maybe Int) FunctionOrData | A label literal. Parameters: 1) The name of the symbol mentioned in the declaration 2) The size (in bytes) of the arguments
the label expects. Only applicable with
3) Flag indicating whether the symbol references a function or a data |
Instances
| Data Literal # | |
Defined in GHC.Types.Literal Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> Literal -> c Literal Source # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c Literal Source # toConstr :: Literal -> Constr Source # dataTypeOf :: Literal -> DataType Source # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c Literal) Source # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c Literal) Source # gmapT :: (forall b. Data b => b -> b) -> Literal -> Literal Source # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> Literal -> r Source # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> Literal -> r Source # gmapQ :: (forall d. Data d => d -> u) -> Literal -> [u] Source # gmapQi :: Int -> (forall d. Data d => d -> u) -> Literal -> u Source # gmapM :: Monad m => (forall d. Data d => d -> m d) -> Literal -> m Literal Source # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> Literal -> m Literal Source # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> Literal -> m Literal Source # | |
| Binary Literal # | |
| Outputable Literal # | |
| Eq Literal # | |
| Ord Literal # | Needed for the |
data LitNumType #
Numeric literal type
Constructors
| LitNumInteger |
|
| LitNumNatural |
|
| LitNumInt |
|
| LitNumInt64 |
|
| LitNumWord |
|
| LitNumWord64 |
|
Instances
Creating Literals
mkLitIntWrap :: Platform -> Integer -> Literal #
Creates a Literal of type Int#.
If the argument is out of the (target-dependent) range, it is wrapped.
See Note [WordInt underflowoverflow]
mkLitIntUnchecked :: Integer -> Literal #
Creates a Literal of type Int# without checking its range.
mkLitWordWrap :: Platform -> Integer -> Literal #
Creates a Literal of type Word#.
If the argument is out of the (target-dependent) range, it is wrapped.
See Note [WordInt underflowoverflow]
mkLitInt64 :: Integer -> Literal #
Creates a Literal of type Int64#
mkLitInt64Wrap :: Platform -> Integer -> Literal #
Creates a Literal of type Int64#.
If the argument is out of the range, it is wrapped.
mkLitWord64 :: Integer -> Literal #
Creates a Literal of type Word64#
mkLitWord64Wrap :: Platform -> Integer -> Literal #
Creates a Literal of type Word64#.
If the argument is out of the range, it is wrapped.
mkLitFloat :: Rational -> Literal #
Creates a Literal of type Float#
mkLitDouble :: Rational -> Literal #
Creates a Literal of type Double#
mkLitString :: String -> Literal #
Creates a Literal of type Addr#, which is appropriate for passing to
e.g. some of the "error" functions in GHC.Err such as GHC.Err.runtimeError
mkLitInteger :: Integer -> Literal #
mkLitNatural :: Integer -> Literal #
mkLitNumber :: Platform -> LitNumType -> Integer -> Literal #
Create a numeric Literal of the given type
mkLitNumberWrap :: Platform -> LitNumType -> Integer -> Literal #
Create a numeric Literal of the given type
Operations on Literals
literalType :: Literal -> Type #
Find the Haskell Type the literal occupies
absentLiteralOf :: TyCon -> Maybe Literal #
litNumIsSigned :: LitNumType -> Bool #
Indicate if a numeric literal type supports negative numbers
litNumCheckRange :: Platform -> LitNumType -> Integer -> Bool #
Check that a given number is in the range of a numeric literal
Predicates on Literals and their contents
litIsDupable :: Platform -> Literal -> Bool #
True if code space does not go bad if we duplicate this literal
litIsTrivial :: Literal -> Bool #
True if there is absolutely no penalty to duplicating the literal. False principally of strings.
"Why?", you say? I'm glad you asked. Well, for one duplicating strings would blow up code sizes. Not only this, it's also unsafe.
Consider a program that wants to traverse a string. One way it might do this is to first compute the Addr# pointing to the end of the string, and then, starting from the beginning, bump a pointer using eqAddr# to determine the end. For instance,
-- Given pointers to the start and end of a string, count how many zeros
-- the string contains.
countZeros :: Addr# -> Addr# -> -> Int
countZeros start end = go start 0
where
go off n
| off `addrEq#` end = n
| otherwise = go (off `plusAddr#` 1) n'
where n' | isTrue# (indexInt8OffAddr# off 0# ==# 0#) = n + 1
| otherwise = n
Consider what happens if we considered strings to be trivial (and therefore
duplicable) and emitted a call like countZeros "hello"# ("hello"#
. The beginning and end pointers do not belong to the same
string, meaning that an iteration like the above would blow up terribly.
This is what happened in #12757.plusAddr# 5)
Ultimately the solution here is to make primitive strings a bit more structured, ensuring that the compiler can't inline in ways that will break user code. One approach to this is described in #8472.
litIsLifted :: Literal -> Bool #
inCharRange :: Char -> Bool #
litFitsInChar :: Literal -> Bool #
isLitValue :: Literal -> Bool #
isLitValue_maybe :: Literal -> Maybe Integer #
Coercions
word2IntLit :: Platform -> Literal -> Literal #
int2WordLit :: Platform -> Literal -> Literal #
narrowLit :: forall a. Integral a => Proxy a -> Literal -> Literal #
Narrow a literal number (unchecked result range)
narrow8IntLit :: Literal -> Literal #
narrow16IntLit :: Literal -> Literal #
narrow32IntLit :: Literal -> Literal #
narrow8WordLit :: Literal -> Literal #
narrow16WordLit :: Literal -> Literal #
narrow32WordLit :: Literal -> Literal #
char2IntLit :: Literal -> Literal #
int2CharLit :: Literal -> Literal #
float2IntLit :: Literal -> Literal #
int2FloatLit :: Literal -> Literal #
double2IntLit :: Literal -> Literal #
int2DoubleLit :: Literal -> Literal #
nullAddrLit :: Literal #
rubbishLit :: Literal #
A nonsense literal of type forall (a :: .TYPE UnliftedRep). a
float2DoubleLit :: Literal -> Literal #
double2FloatLit :: Literal -> Literal #