1. LING/C SC/PSYC 438/538
Lecture 4
Sandiway Fong

2. Administrivia Today's Topics
Quick Homework 4 graded (you should have an from me)
Today's Topics
Terminal log from last time
A note on Windows 10 and quoting
Review of Homework 4
Continuing on with perlintro (scalars and arrays)

3. Terminal: from last time
~$ perl test.perl Can't open perl script "test.perl": No such file or directory ~$ pwd /Users/sandiway ~$ cd Desktop Desktop$ pwd /Users/sandiway/Desktop Desktop$ perl test.perl Hello, worldDesktop$ perl test.perl Hello, world Hello, world\nDesktop$ perl test.perl
Desktop$ perl test.perl Hello, world Desktop$ perl -e 'print "Hello, World"' Hello, WorldDesktop$ perl -e 'print "Hello, World\n"' Hello, World Desktop$ perl -le 'print "Hello, World"' Name "main::Hello" used only once: possible typo at test.perl line 3. print() on unopened filehandle Hello at test.perl line 3.

4. Terminal: from last time
Desktop$ perl test.perl Global symbol "$Hello" requires explicit package name (did you forget to declare "my $Hello"?) at test.perl line 3. Global symbol "$Hello" requires explicit package name (did you forget to declare "my $Hello"?) at test.perl line 4. Execution of test.perl aborted due to compilation errors. This is a stringDesktop$ perl test.perl This is a string\nDesktop$ perl test.perl This is a string
Desktop$ perl test.perl Name "main::Hello" used only once: possible typo at test.perl line 3. Name "main::Helo" used only once: possible typo at test.perl line 4. Use of uninitialized value $Helo in string at test.perl line 4.

5. Terminal: from last time
Desktop$ perl test.perl Global symbol "$Hello" requires explicit package name (did you forget to declare "my $Hello"?) at test.perl line 3. Global symbol "$Helo" requires explicit package name (did you forget to declare "my $Helo"?) at test.perl line 4. Execution of test.perl aborted due to compilation errors. Desktop$
MacOS:
aquamacs editor
TextEdit
Linux:
nano
emacs
Windows 10:
Notepad

6. Terminal: from last time
Windows 10 command prompt
single quotes not recognized as quotes
double quotes can be used
inside the (initial) double quotes, everything will be passed to Perl:
you can use single quotes
you can escape double quotes, i.e. \" to get a double quote.

7. Terminal: from last time
You can also use PowerShell in Windows 10:
both single and double quotes can be used as quoting characters in the shell.
Inside the initial quotes, you can escape any quotes that need to be passed to Perl.

8. Terminal: from last time
~$ cd Desktop Desktop$ python3 Python (v3.7.3:ef4ec6ed12, Mar , 16:52:21) [Clang 6.0 (clang )] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> print("Hello, World") Hello, World >>> print "Hello, world\n"; File "<stdin>", line 1 print "Hello, world\n"; >>>
SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Hello, world\n")? >>> print "Hello, world\n"; File "<stdin>", line 1 print "Hello, world\n"; ^ >>> >>> print("Hello, World") Hello, World >>> print('Hello, World') >>> print('Hello, World\n') >>> print('Hello, World\n\n\n\n\n')

9. Homework 4 Review 1. Commas are important people.
Q2: Run the these two sentences on the Berkeley Parser. Critique the parse. (
Q3: Compare with the Google Parser. Critique the dependency parses. (

10. Homework 4 Review
Berkeley Parser

11. Homework 4 Review Google Parser
ATTR - link between a verb like 'be/seem/appear' and its complement
attr has been removed as a relation. attr was a relation intended for the complement of a copular verb such as “to be”, “to seem”, “to appear”. Mainly, it was used for WHNP complements. (The relation attr was meant to stand for “attributive” but that was arguably a misuse of the word.)

12. Homework 4 Review
Periods are important, people!
Compare!

13. Homework 4 Review
Capitalization is important, people!
Compare!

14. print as a statement vs. function
Perl
Python3
Same behavior, different assumptions about end of line (\n) from these two programming languages
"\" is the escape character
Note also the differences in syntax:
(..) in Python3, no parentheses (needed) in Perl
; need to separate the statements in Perl, none in Python

15. Perl vs. Python3
Scalars: (basically things that take up one 32/64 bit word of memory)
variables begin with ($) - no such type requirement in Python
Numbers (integer, floating point)
Python includes complex numbers (cmath library)
Strings (double ".." or single quoted '..')
References (pointers to (non-)scalars)

16. Perl vs. Python3 Variable interpolation Perl: Python3: Python2.7:
print "My name is $name\n";
print "My name is \$name\n";
print 'My name is \$name\n';
Python3:
print("My name is", name)
Python2.7:
Note: white spacing

17. perlintro: Arrays
like a simple ordered list… (in Python, we use a list)
Literal:
@ARRAY = ( … , … , …) (round brackets; comma separator)
Python: array = [… , … , … ]
Access:
$ARRAY[ INDEX] (zero-indexed; negative indices ok; slices ok)
Python: array[index]
Index of last element:
 $#array (a scalar)
Python: len(array)-1 array[-1]
Coercion
@ARRAY = number of elements in scalar context
Python: len(array)
Built-in functions:
$ELEMENT; $ELEMENT, $OFFSET, $LENGTH, $ELEMENT
$ELEMENT above can
Python: array.sort(), array.reverse()
Built-in arrays:
@ARGV (command line arguments)
@_ (sub(routine) arguments)

18. perlintro Notes from the tutorial:
semicolon (;) is not always necessary
Command separator semantics vs. end of command (termination) token
Best practice? Terminate every command with a semicolon
Variable types:
Every variable type has its own namespace.
This means that $foo are two different variables.
It also means that $foo[1] is a part not a part of $foo. This may seem a bit weird, but that's okay, because it is weird.

19. Perl Arrays Arrays: A note on output: Idea: list of scalars
like a simple ordered list (cf. Python lists)
access by index: 0,1,2,…
negative indices count from the end
A note on output:
zeroonetwothreefour
print zero one two three four
controlled by system variable $"
default value: a space

20. perlintro: Perl Arrays
like a simple ordered list… (in Python, we use a list)
Literal:
@ARRAY = ( … , … , …) (round brackets; comma separator)
Python: array = [… , … , … ]
Access:
$ARRAY[ INDEX] (zero-indexed; negative indices ok; slices ok)
Python: array[index]
Index of last element:
 $#array (a scalar)
Python: len(array)-1 (access: array[-1])

21. Shell quoting Bash shell (MacOS, Linux): cf. Windows 10 slide earlier
manual:
can't write:
perl -e print

22. Shell quoting Bash shell (MacOS, Linux): can write:
perl -e print

23. perlintro: Perl Arrays
like a simple ordered list… (in Python, we use a list)
Coercion
@ARRAY = number of elements in scalar context
Python (no coercion): len(array)
Built-in functions:
$ELEMENT; $ELEMENT, $OFFSET, $LENGTH, $ELEMENT
$ELEMENT above can
Python: array.sort(), array.reverse(), NO push (use array.append() instead), array.pop(), No shift/unshift etc…
Built-in arrays:
@ARGV (command line arguments)
@_ (sub(routine) arguments)

24. perlintro: Perl Arrays
Similar to pop/push, but operates at the left end of the array
Python doesn't have these defined but can be simulated via slicing and concatenation:
array[1:]
list + array

25. perlintro: Perl Arrays