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![DocOnDev
Requirements
Takes a String of integers and returns their sum
Can handle an unknown amount of integers
Can handle a custom delimiter
Delimiter notation “//[delimiter]n[numbers]”
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-29-320.jpg)
![DocOnDev
Requirements
Takes a String of integers and returns their sum
Can handle an unknown amount of integers
Can handle a custom delimiter
Delimiter notation “//[delimiter]n[numbers]”
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-42-320.jpg)
![DocOnDev
Requirements
Takes a String of integers and returns their sum
Can handle an unknown amount of integers
Can handle a custom delimiter
Delimiter notation “//[delimiter]n[numbers]”
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-45-320.jpg)
![DocOnDev
String Calculator Code
string-calculator.ss
(define (str-calc input [delim #,])
(cond ((list? input)
(cond ((null? input) 0)
(else (+ (string->number (car input))
(str-calc (cdr input))))))
((= (string-length input) 0) 0)
(else (str-calc (str-split input delim)))))
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-48-320.jpg)
![DocOnDev
Requirements
Takes a String of integers and returns their sum
Can handle an unknown amount of integers
Can handle a custom delimiter
Delimiter notation “//[delimiter]n[numbers]”
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-52-320.jpg)
![DocOnDev
Requirements
Takes a String of integers and returns their sum
Can handle an unknown amount of integers
Can handle a custom delimiter
Delimiter notation “//[delimiter]n[numbers]”
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-58-320.jpg)
![DocOnDev
Ruby - Mario Aquino
module Calculator
def self.calculate(expression)
raise ArgumentError, 'Must be a string' unless expression.is_a? String
raise ArgumentError, 'Must be numeric' unless expression =~ pattern
value = nil
expression.scan(pattern) do |left, operator, right|
value ||= left
value = eval(value + operator + right).to_s
end
value
end
private
def self.pattern
/(d+)s?([+-*/])s*(?=(d+))/
end
end
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-59-320.jpg)
![DocOnDev
Python - Gary Bernhardt
def add(string):
string = _normalize_delimiters(string)
if string:
return _add_numbers_in_string(string)
else:
return 0
def _normalize_delimiters(string):
string = _normalize_custom_delimiter(string)
string = string.replace('n', ',')
return string
def _normalize_custom_delimiter(string):
if string.startswith('//'):
delimiter_spec, string = string.split('n', 1)
delimiter = delimiter_spec[2:]
string = string.replace(delimiter, ',')
return string
def _add_numbers_in_string(string):
numbers = map(int, string.split(','))
_validate_numbers(numbers)
return sum(numbers)
def _validate_numbers(numbers):
if any(number < 0 for number in numbers):
raise ValueError
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-60-320.jpg)
![DocOnDev
F# - Mark Needham
module FSharpCalculator
open System
open System.Text.RegularExpressions
let split (delimeter:array<string>) (value:string) = value.Split (delimeter, StringSplitOptions.None)
let toDecimal value = Decimal.Parse value
let (|CustomDelimeter|NoCustomDelimeter|) (value:string) =
let delimeters (value:string) = Regex.Matches(value, "[([^]]*)]") |> Seq.cast |>
Seq.map (fun (x:Match) -> x.Groups) |>
Seq.map (fun x -> x |> Seq.cast<Group> |> Seq.nth 1) |>
Seq.map (fun x -> x.Value) |>
Seq.to_array
if (value.Length > 2 && "//".Equals(value.Substring(0, 2))) then
if ("[".Equals(value.Substring(2,1))) then CustomDelimeter(delimeters value)
else CustomDelimeter([| value.Substring(2, value.IndexOf("n") - 2) |])
else NoCustomDelimeter(",")
let digits value = match value with
| CustomDelimeter(delimeters) -> value.Substring(value.IndexOf("n")) |> split delimeters |> Array.map toDecimal
| NoCustomDelimeter(delimeter) -> value.Replace("n", delimeter) |> split [|delimeter |] |> Array.map toDecimal
let buildExceptionMessage negatives =
sprintf "No negative numbers allowed. You provided %s" (String.Join(",", negatives |> Array.map (fun x -> x.ToString())))
let (|ContainsNegatives|NoNegatives|) digits =
if (digits |> Array.exists (fun x -> x < 0.0m))
then ContainsNegatives(digits |> Array.filter (fun x -> x < 0.0m))
else NoNegatives(digits)
let add value = if ("".Equals(value) or "n".Equals(value)) then 0.0m
else match digits value |> Array.filter (fun x -> x < 1000m) with
| ContainsNegatives(negatives) -> raise (ArgumentException (buildExceptionMessage negatives))
| NoNegatives(digits) -> digits |> Array.sum
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-61-320.jpg)
![DocOnDev
C# - Anonymous
using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
namespace TDDFun
{
public class StringCalculator
{
public double Add(string numbers)
{
Double sum = 0;
if (string.IsNullOrEmpty(numbers))
{
sum = 0;
}
else
{
const string regex1 = “(//)”;
const string regex2 = “(.*?)”;
const string regex3 = “(n)”;
const string regex4 = “(.*?d)”;
var delimiters = new List<string>();
var r = new Regex(regex1 + regex2 + regex3 + regex4, RegexOptions.IgnoreCase | RegexOptions.Singleline);
Match m = r.Match(numbers);
if (m.Success)
{
string delimiterCollection = m.Groups[2].ToString();
int numberStartIndex = m.Groups[3].Index;
const string re5 = “([.*?])”;
var r2 = new Regex(re5, RegexOptions.IgnoreCase | RegexOptions.Singleline);
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-62-320.jpg)
![DocOnDev
C# - Anonymous (cont.)
MatchCollection m2 = r2.Matches(delimiterCollection);
if (m2.Count > 0)
{
foreach (Match x in m2)
{
delimiters.Add(x.ToString().Replace(“[", "").Replace("]“, “”));
}
}
else
{
delimiters.Add(delimiterCollection);
}
numbers = numbers.Remove(0, numberStartIndex + 1);
}
else
{
delimiters.Add(“n”);
delimiters.Add(“,”);
}
string[] splittedNumbers = numbers.Split(delimiters.ToArray(), StringSplitOptions.None);
ValiateNumbers(splittedNumbers);
foreach (string s in splittedNumbers)
{
double ss = Double.Parse(s);
sum += ss <= 1000 ? ss : 0;
}
}
return sum;
}
CodeMash 2.0.1.0](https://image.slidesharecdn.com/codemash-2-0-1-0-100117160418-phpapp01/85/Introduction-to-Functional-Programming-with-Scheme-63-320.jpg)
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Uploaded byDoc Norton
Introduction to Functional Programming with Scheme
The document discusses functional programming concepts like immutability, referential transparency, and higher-order functions. It also discusses the Lisp and Scheme programming languages, focusing on key aspects of Scheme like static scope, tail recursion, and shared namespaces. The document walks through an example of implementing a string calculator kata in Scheme, including test cases, failures, and fixes to the implementation code to pass all tests.
