StdBool¶
This module can be imported directly or as a part of the StdEnv module.
It provides definitions for logical operations.
Although the size of the module is small compare to other primitive data types provided by CLEAN, this module is still quite important, on the account that it defines logical equivalence.
That is correct, without this module, CLEAN has no idea how to perform one of the most fundamental operation is Boolean algebra.
Visit StdBool on Cloogle for source code of this module.
Logical operations¶
Three logical operations are defined by this module.
Logical equivalence¶
Signature
// CLEAN
(==) infix 4 :: Bool Bool -> Bool
(==) a b => ...
Behavior
Returns true if both operands have the same logical value. Otherwise, returns false.
Usage
// CLEAN
True == True // True
True == False // False
False == True // False
False == False // True
Logical inclusive disjunction¶
Signature
// CLEAN
(||) infixr 2 :: Bool Bool -> Bool
(||) a b => ...
Behavior
Returns true if at least one operand is true. Otherwise, returns false.
Usage
// CLEAN
True || True // True
True || False // True
False || True // True
False || False // False
Logical conjunction¶
Signature
// CLEAN
(&&) infixr 3 :: Bool Bool -> Bool
(&&) a b => ...
Behavior
Returns true if both operands are true. Otherwise, returns false.
Usage
// CLEAN
True && True // True
True && False // False
False && True // False
False && False // False
Logical functions¶
Technically speaking, logical negation is a unary operator, there is no such thing as a unary operator in CLEAN, as much as it pains me, I have decided to place it here.
Logical negation¶
Signature
// CLEAN
not :: Bool -> Bool
not a => ...
Behavior
Negates the logical value of a.
Usage
// CLEAN
not True // False
not False // True
Conversions from Boolean¶
The function which is responsible for converting Boolean to other types is overloaded, which means the desired type must be unambiguous.
Natively, Boolean may convert to string, but additional behavior may be added by creating new instances of fromBool class from the StdOverloaded module.
To string¶
Signature
// CLEAN
fromBool :: Bool -> {#Char}
fromBool a => ...
Behavior
Returns the string representation of a which is either "True" or "False".
Usage
// CLEAN
expr :: {#Char}
expr = fromBool True // "True"
expr = fromBool False // "False"