CondLink

CondLink is a kind of FunctionLink that implements branching similar to what is found in functional programming languages, such as scheme [1].

Syntax

CondLink has two syntaxes, conditions and expressions can be flattened or wrapped in list link.

Flattened Syntax:

CondLink
 <condition-1>
 <expression-2>
 ...
 <condition-n>
 <expression-n>
 <default-expression>		

where <condition-i> is a kind of EvaluatableLink.

Wrapped syntax:

CondLink
 ListLink
  <condition-1>
  <expression-1>
  ...
 ListLink
  TrueLink
  <default-expression>

Semantics

As a ternary operation:

CondLink
 C
 E
 D

The above will execute E only if C is evaluated to crisp-logic True. Other wise the default expression D gets executed. And this is identical to a IfThenElseLink.

As n-ary operation:

CondLink
 C-1
 E-1
 ...
 C-n
 E-n
 D

The above will execute E-i only if C-i is evaluated to crisp-logic True. Where i is the index [1, n] for the first True evaluated condition. Other wise the default expression D gets executed.

Examples

(cog-execute!
   (CondLink
       (GreaterThanLink
           (NumberNode 2)
           (NumberNode 1))
       (PlusLink
           (NumberNode 2)
           (NumberNode 3))
       (NumberNode -1)))

will yield

(NumberNode 5)

Note that some similar operations can be acheived with MinLink, MaxLink and HeavisideLink.

See also

• SequentialAndLink
• SequentialOrLink