
GHC.Exts  Portability  nonportable (GHC Extensions)  Stability  internal  Maintainer  cvsghc@haskell.org 





Description 
GHC Extensions: this is the Approved Way to get at GHCspecific extensions.


Synopsis 




Representations of some basic types


data Int 
A fixedprecision integer type with at least the range [2^29 .. 2^291].
The exact range for a given implementation can be determined by using
minBound and maxBound from the Bounded class.
 Constructors   Instances  


data Word 
A Word is an unsigned integral type, with the same size as Int.
 Constructors   Instances  


data Float 
Singleprecision floating point numbers.
It is desirable that this type be at least equal in range and precision
to the IEEE singleprecision type.
 Constructors   Instances  


data Double 
Doubleprecision floating point numbers.
It is desirable that this type be at least equal in range and precision
to the IEEE doubleprecision type.
 Constructors   Instances  


data Integer 
Arbitraryprecision integers.
 Constructors  S# Int#   J# Int# ByteArray#  
 Instances  


data Char 
The character type Char is an enumeration whose values represent
Unicode (or equivalently ISO/IEC 10646) characters
(see http://www.unicode.org/ for details).
This set extends the ISO 88591 (Latin1) character set
(the first 256 charachers), which is itself an extension of the ASCII
character set (the first 128 characters).
A character literal in Haskell has type Char.
To convert a Char to or from the corresponding Int value defined
by Unicode, use toEnum and fromEnum from the
Enum class respectively (or equivalently ord and chr).
 Constructors   Instances  


data Ptr a 
A value of type Ptr a represents a pointer to an object, or an
array of objects, which may be marshalled to or from Haskell values
of type a.
The type a will often be an instance of class
Storable which provides the marshalling operations.
However this is not essential, and you can provide your own operations
to access the pointer. For example you might write small foreign
functions to get or set the fields of a C struct.
 Constructors   Instances  


data FunPtr a 
A value of type FunPtr a is a pointer to a function callable
from foreign code. The type a will normally be a foreign type,
a function type with zero or more arguments where
 the argument types are marshallable foreign types,
i.e. Char, Int, Double, Float,
Bool, Int8, Int16, Int32,
Int64, Word8, Word16,
Word32, Word64, Ptr a, FunPtr a,
StablePtr a or a renaming of any of these
using newtype.
 the return type is either a marshallable foreign type or has the form
IO t where t is a marshallable foreign type or ().
A value of type FunPtr a may be a pointer to a foreign function,
either returned by another foreign function or imported with a
a static address import like
foreign import ccall "stdlib.h &free"
p_free :: FunPtr (Ptr a > IO ())
or a pointer to a Haskell function created using a wrapper stub
declared to produce a FunPtr of the correct type. For example:
type Compare = Int > Int > Bool
foreign import ccall "wrapper"
mkCompare :: Compare > IO (FunPtr Compare)
Calls to wrapper stubs like mkCompare allocate storage, which
should be released with freeHaskellFunPtr when no
longer required.
To convert FunPtr values to corresponding Haskell functions, one
can define a dynamic stub for the specific foreign type, e.g.
type IntFunction = CInt > IO ()
foreign import ccall "dynamic"
mkFun :: FunPtr IntFunction > IntFunction
 Constructors   Instances  


Primitive operations


module GHC.Prim 

shiftL# :: Word# > Int# > Word# 
Shift the argument left by the specified number of bits
(which must be nonnegative).


shiftRL# :: Word# > Int# > Word# 
Shift the argument right by the specified number of bits
(which must be nonnegative).


iShiftL# :: Int# > Int# > Int# 
Shift the argument left by the specified number of bits
(which must be nonnegative).


iShiftRA# :: Int# > Int# > Int# 
Shift the argument right (signed) by the specified number of bits
(which must be nonnegative).


iShiftRL# :: Int# > Int# > Int# 
Shift the argument right (unsigned) by the specified number of bits
(which must be nonnegative).


Fusion


build :: forall a . (forall b . (a > b > b) > b > b) > [a] 
A list producer that can be fused with foldr.
This function is merely
build g = g (:) []
but GHC's simplifier will transform an expression of the form
foldr k z (build g), which may arise after inlining, to g k z,
which avoids producing an intermediate list.


augment :: forall a . (forall b . (a > b > b) > b > b) > [a] > [a] 
A list producer that can be fused with foldr.
This function is merely
augment g xs = g (:) xs
but GHC's simplifier will transform an expression of the form
foldr k z (augment g xs), which may arise after inlining, to
g k (foldr k z xs), which avoids producing an intermediate list.


Linear implicit parameter support


class Splittable t where 


Debugging


breakpoint :: a > a 

Ids with special behaviour


lazy :: a > a 
The call '(lazy e)' means the same as e, but lazy has a
magical strictness property: it is lazy in its first argument,
even though its semantics is strict.


inline :: a > a 
The call '(inline f)' reduces to f, but inline has a BuiltInRule
that tries to inline f (if it has an unfolding) unconditionally
The NOINLINE pragma arranges that inline only gets inlined (and
hence eliminated) late in compilation, after the rule has had
a god chance to fire.


Produced by Haddock version 0.8 