A Taste of Boo

# Just a taste of Boo ...
# Boo is a language that can be interpreted (with Booi.exe) or compiled
# (with Booc.exe), there is even a shell similar to the Python shell (Booish.exe).
# Boo works in the NET or MONO environment on Windows or Unix systems.
# You may notice the Python like syntax and some concepts borrowed from C#, Perl
# and Ruby.  It is easy to translate Python to Boo, but there are differences!
# Boo is open source and you can download it from: http://boo.codehaus.org/
# You do need the Microsoft NET or open source MONO environment on your machine.
# Most any programmer's editor will do, or download Booxw.exe from the above site.
# The Boo plugin for the SharpDevelop IDE works well too.
# tested with BOO_0.7.0       vegaseat      09nov2005

/*
one line comments start with a Python # or a C //
you are looking at an example of a multiline comment
*/

# any imports have to be done first ...
import System.IO  // for Directory

# next come all classes and functions ...
# (at least at this point in time)

# the indented lines are part of the function
# Boo uses the Python indented statement block
# the function's argument types have to be declared
# function return types can be inferred

def convertFahrenheit2Celsius(fahrenheit as double):
"""this would be the document string for the function"""
    celcius = 0.555 * (fahrenheit - 32)
    return celcius


# simple stuff first ...
print "Show a result the Python way ..."
print "Simple math like 12345679*63 =", 12345679*63

print "\n... or using Boo string interpolation ..."
print "Simple math like 12345679*63 = ${12345679*63}"

# print just an empty line
print

print "Display numbers 0 to 9 ..."
# the indentation makes the print statement part of the loop
for number in range(10):
    print number

print

print "Display numbers 0 to 9 on one line ..."
# print is a macro of System.Console.WriteLine() and adds a newline
# use System.Console.Write() to stay on the same line
# (using a comma to prevent the newline like in Python gives an error with Boo)

for number in range(10):
    //print number,
    System.Console.Write(number)
    
print; print

# just in case you think Boo has only for loops
# there is a while loop too
print "Count from 10 to 15, skip 13 ..."
k = 10
while k <= 15:
    unless k == 13:
        print k
    k++

# print 50 dashes
print "-"*50

# a little more complex this time
# Boo does have its roots in the C# language
# so we are using C# format specifiers in the output
# (the Python C-like format specifier % does not work!)
print "Square root of integers 0 to 9 formatted as a float with 4 decimals:"
for value in range(10):
    squareRoot = System.Math.Sqrt(value)
    System.Console.WriteLine("sqrt({0:D1}) = {1:F4}", value, squareRoot)

print

print "A not so typical for loop:"
for food in "spam", "eggs", "cumquats":
    print "I love", food

print

# strings can be enclosed in " or '
# (only " allows string interpolation)
animal = "hippopotamus"
print "this is the string    = ", animal
print "length of string      = ", len(animal)

# a short intro to string slicing
# a little cryptic at first blush, but very powerful
# [begin : < end]  note: end is exclusive
# defaults are begin = 0, end = length
# Python also has step, which is not implemented yet in Boo ...
print "exclude first 3 char  = ", animal[3: ]
print "exclude last 4 char   = ", animal[:-4]

print "reverse the string:"
for c in reversed(animal):
    System.Console.Write(c)
    
print; print

print "reverse first name and last name:"
name = "Ferdinand Porsche"
# Boo has built-in regex support, \s is space
firstname, lastname = @/\s/.Split(name)
print lastname, firstname

# or you can do it the no-regex way ...
firstname, lastname = name.Split()   # default is whitespace
print lastname, firstname

print

# Boo has lists similar to Python
list1 = List(range(8))
print list1.GetType()    # Boo.Lang.List
print list1              # [0, 1, 2, 3, 4, 5, 6, 7]
print "number of items in list       = ", len(list1)

# lists can be sliced too ...
print "exclude first 3 items in list = ", list1[3:]
print "first 3 items in list         = ", list1[:3]
print "exclude last 2 items in list  = ", list1[:-2]

# create a list of all items above value 3 ...
# (do behaves like a function)
list2 = list1.Collect() do (item as int):
    return item > 3
print "list1         = ", list1
print "all items > 3 = ", list2

# add to the list with Add or Push ...
list1.Add("any")
list1.Push("type")

# add another list ...
list1.Extend(["can", "be added", 3.1415])

print "added more items:", list1

# index is zero based
print "'any' is at index", list1.IndexOf('any')

# find 'can' ...
if 'can' in list1:
    print "'can' has been found"
# or ...
print "indeed 'can' has been found" if 'can' in list1

# use list comprehension ...
list3 = [k for k in list1 if k isa string]
print "just the string items: ", list3     # [any, type, can, be added]

# join the strings in list3 ...
str1 = list3.Join(" ")
print "join the strings: ", str1           # any type can be added   

print

# Boo has arrays that are similar to Python tuples
arr1 = array('ABCDE')
print arr1            # System.Object[]
print arr1.GetType()  # System.Object[]
print List(arr1)      # [A, B, C, D, E]
print arr1[1]         # B

if arr1[1] isa string:
    print arr1[1]
else:
    print arr1[1].GetType()  # System.Char

for item in arr1:
    print item, cast(int, item)  # prints char and ASCII number eg.  A 65

print

print "Test boolean results ..."
print "Is 3 > 5? Result =", 3 > 5  # False, yes False and not false as documented
print "Is 3 < 5? Result =", 3 < 5  # True

print

/*
Duck typing was coined by Dave Thomas in the Ruby community: 
"if it walks like a duck, and talks like a duck, then it is a duck".
This is a way to fake being a dynamic language like Python.
Useful, if you don't exactly know the type returned by an external call.
*/

d as duck  // d accepts different types

d = 21     // sets d to an integer
print d
d += 12    // it can do everything an integer does
print d

d = "hypocrite"  // sets d to a string
print d
d = d.ToUpper()  // now it can do everything a string does
print d

print

# show files of a given extension from a given folder
ftype = "*.boo"
folder = "./"    // current folder
//folder = "D:/Boo/BooTest/"  // or specified folder

// print "Show string the Python way ..."
// print "All " + ftype + " files in folder " + folder + " :"

// ... or the Boo way ... 
print "All ${ftype} files in folder ${folder} :"

for fname in Directory.GetFiles(folder, ftype):
    print fname

print

# let's use the function we defined at the beginning
# (make sure you define/create the function before you call it)
print "A Fahrenheit to Celcius table:"
# range is from -40 to < 220 in steps of 10
for tf in range(-40, 220, 10):
    System.Console.WriteLine("{0:F1}F = {1:F1}C", tf, convertFahrenheit2Celsius(tf))

print

print "A more limited table:"
# another variation of the for loop ...
for tf in -40,0,32,98.6:
    System.Console.WriteLine("{0:F1}F = {1:F1}C", tf, convertFahrenheit2Celsius(tf))

prompt("Press enter to exit ...")  // optional console wait