# The Script Programming Language/Primitive Procedures

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The Script Programming Language

Primitive Procedures

Author: Jeff Stephenson

## Primitive Procedures

### Arithmetic primitives:

In the following, e1, e2, ... are arbitrary expressions.

(+ e1 e2 [e3...])
Evaluates to e1 + e2 [+ e3 ...]

(* e1 e2 [e3...])
Evaluates to e1 * e2 [* e3 ...]

(- e1 e2)
Evaluates to e1 - e2

(/ e1 e2)
Evaluates to e1 / e2

(mod e1 e2)
Evaluates to the remainder of e1 when divided by e2.

(<< e1 e2)
Evaluates to e1 << e2 where the << operation shifts its left hand side left by the number of bits specified by its right hand side. (As in C).

(>> e1 e2)
Evaluates to e1 >> e2 as in << except a right shift.

(^ e1 e2 [e3 ...])
Evaluates to e1 ^ e2 [^ e3 ^ ...] where '^' is the bitwise exclusive-or operator.

(& e1 e2 [e3 ...])
Evaluates to e1 & e2 [& e3 & ...] where '&' is the bitwise and operator.

(| e1 e2 [e3])
Evaluates to e1 | e2 [| e3 | ...] where '|' is the bitwise or operator.

(! e1)
Evaluates to TRUE if e1 == 0, else FALSE.

(~ e1)
Evaluates to the bit-wise not of e1, i.e. all 1 bits are changed to 0 and all 0 bits are changed to 1.

### Boolean primitives:

These procedures are always guaranteed to evaluate their parameters left to right and to terminate the moment the truth value of the expression is determined. If the truth value of the boolean is determined before an expression is reached, the expression is never evaluated.

(> e1 e2 [e3...])
Evaluates to TRUE if e1 > e2 [> e3 ...], else FALSE.

(>= e1 e2 [e3...])
Evaluates to TRUE if e1 >= e2 [>= e3 ...], else FALSE.

(< e1 e2 [e3...])
Evaluates to TRUE if e1 < e2 [< e3 ...], else FALSE.

(<= e1 e2 [e3...])
Evaluates to TRUE if e1 <= e2 [<= e3 ...], else FALSE.

(== e1 e2 [e3...])
Evaluates to TRUE if e1 == e2 [== e3 ...], else FALSE.

(!= e1 e2 [e3...])
Evaluates to TRUE if e1 != e1 [!= e3 ...], else FALSE.

(and e1 e2 [e3...])
Evaluates to TRUE if all the expressions are non-zero, else FALSE.

(or e1 e2 [e3...])
Evaluates to TRUE if any of the expressions are non-zero, else FALSE.

(not e)
Evaluates to TRUE if the expression is zero, else FALSE.

### Assignment primitives:

All assignment procedures store a value in a variable and return that value as the result of the assignment. In the following, v is a variable and e an expression.

(= v e)
v = e

(+= v e)
v = v + e

(-= v e)
v = v - e

(*= v e)
v = v * e

(/= v e)
v = v / e

(|= v e)
v = v | e

(&= v e)
v = v & e

(^= v e)
v = v ^ e

(>>= v e)
v = v >> e

(<<= v e)
v = v << e

(++ v)
v = v + 1

(-- v)
v = v - 1

Notes