Catamorphism: Difference between revisions
Add CLU
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</lang>
=={{header|CLU}}==
<lang clu>% Reduction.
% First type = sequence type (must support S$elements and yield R)
% Second type = right (input) datatype
% Third type = left (output) datatype
reduce = proc [S,R,L: type] (f: proctype (L,R) returns (L),
id: L,
seq: S)
returns (L)
where S has elements: itertype (S) yields (R)
for elem: R in S$elements(seq) do
id := f(id, elem)
end
return(id)
end reduce
% This is necessary to get rid of the exceptions
add = proc (a,b: int) returns (int) return (a+b) end add
mul = proc (a,b: int) returns (int) return (a*b) end mul
% Usage
start_up = proc ()
% abbreviation - reducing int->int->int function over an array[int]
int_reduce = reduce[array[int], int, int]
po: stream := stream$primary_output()
nums: array[int] := array[int]$[1,2,3,4,5,6,7,8,9,10]
% find the sum and the product using reduce
sum: int := int_reduce(add, 0, nums)
product: int := int_reduce(mul, 1, nums)
stream$putl(po, "The sum of [1..10] is: " || int$unparse(sum))
stream$putl(po, "The product of [1..10] is: " || int$unparse(product))
end start_up</lang>
{{out}}
<pre>The sum of [1..10] is: 55
The product of [1..10] is: 3628800</pre>
=={{header|Common Lisp}}==
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