Module Unsafe

Library containing unsafe operations. These operations should be carefully used (e.g., for testing or debugging). These operations should not be used in application programs!

Author: Michael Hanus, Bjoern Peemoeller

Version: September 2013

Summary of exported operations:

unsafePerformIO :: IO a -> a   
Performs and hides an I/O action in a computation (use with care!).
trace :: String -> a -> a   
Prints the first argument as a side effect and behaves as identity on the second argument.
spawnConstraint :: Bool -> a -> a   
Spawns a constraint and returns the second argument.
isVar :: a -> Bool   
Tests whether the first argument evaluates to a currently unbound variable (use with care!).
identicalVar :: a -> a -> Bool   
Tests whether both arguments evaluate to the identical currently unbound variable (use with care!).
isGround :: a -> Bool   
Tests whether the argument evaluates to a ground value (use with care!).
compareAnyTerm :: a -> a -> Ordering   
Comparison of any data terms, possibly containing variables.
showAnyTerm :: a -> String   
Transforms the normal form of a term into a string representation in standard prefix notation.
showAnyQTerm :: a -> String   
Transforms the normal form of a term into a string representation in standard prefix notation.
readsAnyUnqualifiedTerm :: [String] -> String -> [(a,String)]   
Transform a string containing a term in standard prefix notation without module qualifiers into the corresponding data term.
readAnyUnqualifiedTerm :: [String] -> String -> a   
Transforms a string containing a term in standard prefix notation without module qualifiers into the corresponding data term.
readsAnyQTerm :: String -> [(a,String)]   
Transforms a string containing a term in standard prefix notation with qualified constructor names into the corresponding data term.
readAnyQTerm :: String -> a   
Transforms a string containing a term in standard prefix notation with qualified constructor names into the corresponding data term.
showAnyExpression :: a -> String   
Transforms any expression (even not in normal form) into a string representation in standard prefix notation without module qualifiers.
showAnyQExpression :: a -> String   
Transforms any expression (even not in normal form) into a string representation in standard prefix notation with module qualifiers.
readsAnyQExpression :: String -> [(a,String)]   
Transforms a string containing an expression in standard prefix notation with qualified constructor names into the corresponding expression.
readAnyQExpression :: String -> a   
Transforms a string containing an expression in standard prefix notation with qualified constructor names into the corresponding expression.

Exported operations:

unsafePerformIO :: IO a -> a   

Performs and hides an I/O action in a computation (use with care!).

Further infos:
  • externally defined

trace :: String -> a -> a   

Prints the first argument as a side effect and behaves as identity on the second argument.

spawnConstraint :: Bool -> a -> a   

Spawns a constraint and returns the second argument. This function can be considered as defined by spawnConstraint c x | c = x. However, the evaluation of the constraint and the right-hand side are performed concurrently, i.e., a suspension of the constraint does not imply a blocking of the right-hand side and the right-hand side might be evaluated before the constraint is successfully solved. Thus, a computation might return a result even if some of the spawned constraints are suspended (use the PAKCS option +suspend to show such suspended goals).

Further infos:
  • externally defined

isVar :: a -> Bool   

Tests whether the first argument evaluates to a currently unbound variable (use with care!).

identicalVar :: a -> a -> Bool   

Tests whether both arguments evaluate to the identical currently unbound variable (use with care!). For instance, identicalVar (id x) (fst (x,1)) evaluates to True whereas identicalVar x y and let x=1 in identicalVar x x evaluate to False

isGround :: a -> Bool   

Tests whether the argument evaluates to a ground value (use with care!).

compareAnyTerm :: a -> a -> Ordering   

Comparison of any data terms, possibly containing variables. Data constructors are compared in the order of their definition in the datatype declarations and recursively in the arguments. Variables are compared in some internal order.

Further infos:
  • externally defined

showAnyTerm :: a -> String   

Transforms the normal form of a term into a string representation in standard prefix notation. Thus, showAnyTerm evaluates its argument to normal form. This function is similar to the function ReadShowTerm.showTerm but it also transforms logic variables into a string representation that can be read back by Unsafe.read(s)AnyUnqualifiedTerm. Thus, the result depends on the evaluation and binding status of logic variables so that it should be used with care!

showAnyQTerm :: a -> String   

Transforms the normal form of a term into a string representation in standard prefix notation. Thus, showAnyQTerm evaluates its argument to normal form. This function is similar to the function ReadShowTerm.showQTerm but it also transforms logic variables into a string representation that can be read back by Unsafe.read(s)AnyQTerm. Thus, the result depends on the evaluation and binding status of logic variables so that it should be used with care!

readsAnyUnqualifiedTerm :: [String] -> String -> [(a,String)]   

Transform a string containing a term in standard prefix notation without module qualifiers into the corresponding data term. The string might contain logical variable encodings produced by showAnyTerm. In case of a successful parse, the result is a one element list containing a pair of the data term and the remaining unparsed string.

readAnyUnqualifiedTerm :: [String] -> String -> a   

Transforms a string containing a term in standard prefix notation without module qualifiers into the corresponding data term. The string might contain logical variable encodings produced by showAnyTerm.

readsAnyQTerm :: String -> [(a,String)]   

Transforms a string containing a term in standard prefix notation with qualified constructor names into the corresponding data term. The string might contain logical variable encodings produced by showAnyQTerm. In case of a successful parse, the result is a one element list containing a pair of the data term and the remaining unparsed string.

readAnyQTerm :: String -> a   

Transforms a string containing a term in standard prefix notation with qualified constructor names into the corresponding data term. The string might contain logical variable encodings produced by showAnyQTerm.

showAnyExpression :: a -> String   

Transforms any expression (even not in normal form) into a string representation in standard prefix notation without module qualifiers. The result depends on the evaluation and binding status of logic variables so that it should be used with care!

Further infos:
  • externally defined

showAnyQExpression :: a -> String   

Transforms any expression (even not in normal form) into a string representation in standard prefix notation with module qualifiers. The result depends on the evaluation and binding status of logic variables so that it should be used with care!

Further infos:
  • externally defined

readsAnyQExpression :: String -> [(a,String)]   

Transforms a string containing an expression in standard prefix notation with qualified constructor names into the corresponding expression. The string might contain logical variable and defined function encodings produced by showAnyQExpression. In case of a successful parse, the result is a one element list containing a pair of the expression and the remaining unparsed string.

readAnyQExpression :: String -> a   

Transforms a string containing an expression in standard prefix notation with qualified constructor names into the corresponding expression. The string might contain logical variable and defined function encodings produced by showAnyQExpression.