How to resolve the algorithm Catamorphism step by step in the ALGOL 68 programming language
Published on 12 May 2024 09:40 PM
How to resolve the algorithm Catamorphism step by step in the ALGOL 68 programming language
Table of Contents
Problem Statement
Reduce is a function or method that is used to take the values in an array or a list and apply a function to successive members of the list to produce (or reduce them to), a single value.
Show how reduce (or foldl or foldr etc), work (or would be implemented) in your language.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Catamorphism step by step in the ALGOL 68 programming language
Source code in the algol programming language
# applies fn to successive elements of the array of values #
# the result is 0 if there are no values #
PROC reduce = ( []INT values, PROC( INT, INT )INT fn )INT:
IF UPB values < LWB values
THEN # no elements #
0
ELSE # there are some elements #
INT result := values[ LWB values ];
FOR pos FROM LWB values + 1 TO UPB values
DO
result := fn( result, values[ pos ] )
OD;
result
FI; # reduce #
# test the reduce procedure #
BEGIN print( ( reduce( ( 1, 2, 3, 4, 5 ), ( INT a, b )INT: a + b ), newline ) ) # sum #
; print( ( reduce( ( 1, 2, 3, 4, 5 ), ( INT a, b )INT: a * b ), newline ) ) # product #
; print( ( reduce( ( 1, 2, 3, 4, 5 ), ( INT a, b )INT: a - b ), newline ) ) # difference #
END
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