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Call a function: Difference between revisions
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Hello world
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=={{header|Lambdatalk}}==
In lambdatalk functions are abstractions {lambda {args} body} whose behaviour is best explained as a part of such a complete expression {{lambda {args} body} values}.
<lang scheme>
The command
replace :a0 :a1 ... an-1
in expression containing some occurences of :ai
by v0 v1 ... vp-1
is rewritten in a prefixed parenthesized form
{{lambda {:a0 :a1 ... an-1}
expression containing some occurences of :ai}
v0 v1 ... vp-1}
so called IIFE (Immediately Invoked Function Expression), and defines an anonymous function containing a sequence of n arguments :ai, immediately invoked on a sequence of p values vi, and returning the expression in its body as so modified:
1) if p < n (partial application)
• the occurrences of the p first arguments are replaced in the function's body by the corresponding p given values,
• a function waiting for missing n-p values is created,
• and its reference is returned.
• example:
{{lambda {:x :y} ... :y ... :x ...} hello}
-> {lambda {:y} ... :y ... hello ...} // replaces :x by hello
-> LAMB_123 // the new functions's reference
• called with the value world this function will return ... world ... hello ...
2) if p = n (normal application)
• the occurences of the n arguments are replaced in the function's body by the corresponding p given values,
• the body is evaluated and the result is returned.
• example
{{lambda {:x :y} ... :y ... :x ...} hello world}
-> {{lambda {:y} ... :y ... hello ...} world} // replaces :x by hello
-> {{lambda {} ... world ... hello ...} } // replaces :y by world
-> ... world ... hello ... // the value
3) if p > n (variadicity)
• the occurrences of the n-1 first arguments are replaced in the function's body by the corresponding n-1 given values,
• the occurrences of the last argument are replaced in the body by the sequence of p-n supernumerary values,
• the body is evaluated and the result is returned.
• example:
{{lambda {:x :y} ... :y ... :x ...} hello world good morning}
-> {{lambda {:y} ... :y ... hello ...} world good morning}
-> {{lambda {} ... world good morning ... hello ...}}
-> ... world good morning ... hello ... // the value
More can be seen in http://lambdaway.free.fr/lambdawalks/?view=lambda
</lang>
=={{header|langur}}==
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