CS 342 Lecture -*- Outline -*-

* Syntax

** lexical
        comments start with %
        no semicolons
        strings in "", characters with '',
		escapes (as in C) '\n' is newline, ...
        operation names have two parts (type, operation)
                int$from_to

** declarations

***	equates
		introduce abbreviations into environment
		for types
			ai = array[int]
		for constants (wholly immutable)
			max_addr = 999
			ops = sequence[int]$[3,4,5]
***	variable declarations
                	y: array[int]
		are statements in CLU
		can have initialization
	                x:int := 3

** statements

        no goto (but have break, continue, exit, return)

***     assignment
                uses :=
                can have multiple variables on lhs
                        x,y := e1,e2
                        x,y := foo(c)   % foo returns 2 objects
                may include declaration
                        i: int := 3

***	compound
	    all compound statements are terminated with "end",
		modules by "end name"

        if then [elseif then] ... else end
        while do end
        for in do end

        no case statement, can use tagcase instead
                (no enumeration types, use oneof or variant instead)

** Syntactic sugars
        (make the syntax "sweeter")

*** Arithmetic operations

------------
        suppose a,b: int
                a + b           =>      int$add(a,b)
                a < b           =>      int$lt(a,b)
                a = b           =>      int$equal(a,b)
                -a              =>      int$minus(a)

        suppose a,b: real
                a + b           =>      real$add(a,b)
                a < b           =>      real$lt(a,b)
                a = b           =>      real$equal(a,b)
                -a              =>      real$minus(a)
------------

*** Boolean operations
------------
        suppose a,b: bool
                a & b           =>      bool$and(a,b)
                a | b           =>      bool$or(a,b)
                a = b           =>      bool$equal(a,b)
                ~a              =>      bool$not(a)
------------
	Special primitives (not sugared operations!) on bools
        cand  - conditional "and", like && in C
        cor   - conditional "or", like || in C
                these cannot be defined as operations
                        because CLU is call by value

*** General comparisons (for most types)
------------
	suppose a,b: T
		a = b		=>	T$equal(a,b)
		a ~= b		=>	bool$not(T$equal(a,b))
		a >= b		=>	T$ge(a,b)
		a > b		=>	T$gt(a,b)
		a <= b		=>	T$le(a,b)
		a < b		=>	T$lt(a,b)
------------