|
|
| Line 46: |
Line 46: |
| | | | |
| | Comments in SCI begin with a semicolon and continue to the end of the line. | | Comments in SCI begin with a semicolon and continue to the end of the line. |
| − |
| |
| − | ==<br /> Primitive Procedures ==
| |
| − |
| |
| − | ===<br /> Arithmetic primitives ===
| |
| − |
| |
| − | In the following examples, e1, e2, etc. are arbitrary expressions. Brackets [...] indicate optional entries. Procedures evaluate their parameters from left to right.
| |
| − |
| |
| − | ====<br /> Addition ====
| |
| − |
| |
| − | <blockquote><code>(+ e1 e2 [e3...])</code></blockquote>
| |
| − |
| |
| − | evaluates to: e1 + e2 [+ e3...]
| |
| − |
| |
| − | example: (+ 7 12 4) evaluates to 23.
| |
| − |
| |
| − | ====<br /> Multiplication ====
| |
| − |
| |
| − | <blockquote><code>(* e1 e2 [e3...])</code></blockquote>
| |
| − |
| |
| − | evaluates to: e1 (*e2[*e3...]
| |
| − |
| |
| − | example: (* 2 10 3) evaluates to 60.
| |
| − |
| |
| − | ====<br /> Subtraction ====
| |
| − |
| |
| − | <blockquote><code>(- e1 e2)</code></blockquote>
| |
| − |
| |
| − | evaluates to : e1 - e2
| |
| − |
| |
| − | example: (- 20 11) evaluates to 9.
| |
| − |
| |
| − | ====<br /> Division ====
| |
| − |
| |
| − | <blockquote><code>(/ e1 e2)</code></blockquote>
| |
| − |
| |
| − | evaluates to: e1 / e2
| |
| − |
| |
| − | example: (/ 24 6) evaluates to 4. <---- Note: does this round when necessary (up, down)?
| |
| − |
| |
| − | ====<br /> Remainder ====
| |
| − |
| |
| − | <blockquote><code>(mod e1 e2)</code></blockquote>
| |
| − |
| |
| − | evaluates to: the remainder of e1 when divided by e2.
| |
| − |
| |
| − | example: (mod 17 5) evaluates to 2.
| |
| − |
| |
| − | ====<br /> Operation Shift Left ====
| |
| − |
| |
| − | <blockquote><code>(<< e1 e2)</code></blockquote>
| |
| − |
| |
| − | evaluates to : e1<< e2 where the << operation shifts its left hand side left by the number of bits specified by its right hand side.
| |
| − |
| |
| − | example: (<< 7 2 ) evaluates to 28.
| |
| − |
| |
| − | In binary: 111 << 2 = 11100
| |
| − |
| |
| − | ====<br /> Operation Shift Right ====
| |
| − |
| |
| − | <blockquote><code>(>> e1 e2)</code></blockquote>
| |
| − |
| |
| − | evaluates to: e1 >> e2 (as in << except with a right shift)
| |
| − |
| |
| − | example: (>> 7 2) evaluates to 1.
| |
| − |
| |
| − | In binary: 111 >> 2 = 001
| |
| − |
| |
| − | ====<br /> Bitwise Exclusive OR Operator ====
| |
| − |
| |
| − | <blockquote><code>(^ e1 e2 [e3...])</code></blockquote>
| |
| − |
| |
| − | evaluates to: e1^ e2 [^ e3...]
| |
| − |
| |
| − | example: (^ 11 26) evaluates to 17.
| |
| − |
| |
| − | In binary: 01011" 11010 = 10001
| |
| − |
| |
| − | ====<br /> Bitwise AND Operator ====
| |
| − |
| |
| − | <blockquote>
| |
| − | {|
| |
| − | |<code>(& e1 e2 [e3...])</code>
| |
| − | |-
| |
| − | |evaluates to: ||e1 &e2 [& e3...]
| |
| − | |-
| |
| − | |''example:'' ||<code>(& 11 26)</code> evaluates to 10.
| |
| − | |-
| |
| − | | ||In binary: 01011 & 11010 = 01010
| |
| − | |}
| |
| − | </blockquote>
| |
| − |
| |
| − | ====<br /> Bitwise OR Operator ====
| |
| − |
| |
| − | <blockquote>
| |
| − | {|
| |
| − | | <code><nowiki>(| e1 e2 [e3...])</nowiki></code>
| |
| − | |-
| |
| − | |evaluates to: ||e1 | e2 [| e3...]
| |
| − | |-
| |
| − | |''example:'' ||<code><nowiki>(| 11 26)</nowiki></code> evaluates to 27.
| |
| − | |-
| |
| − | | ||In binary: 01011 111010 = 11011
| |
| − | |}
| |
| − | </blockquote>
| |
| − |
| |
| − | ====<br /> Bitwise NOT ====
| |
| − |
| |
| − | <blockquote>
| |
| − | {|
| |
| − | |<code>(~ e1)</code>
| |
| − | |-
| |
| − | |evaluates to: ||the bitwise not of e1 (all 1 bits are changed to 0 and all 0 bits are changed to 1).
| |
| − | |-
| |
| − | |''example:'' ||<code>(~ 11)</code> evaluates to -12.
| |
| − | |-
| |
| − | | ||In binary: ~01011 = 1111111111110100 (all the leading 0s in the 16 bit number change to 1s).
| |
| − | |}
| |
| − | </blockquote>
| |
| − |
| |
| − | ===<br /> Boolean primitives ===
| |
| − |
| |
| − | These procedures evaluate their parameters from left to right and terminate the moment the
| |
| − | truth value of the expression is determined. If the truth value of the Boolean expression is
| |
| − | determined before an expression is reached, that expression is never evaluated. Brackets [...]
| |
| − | indicate optional entries. The compiler predefines FALSE to be 0 and TRUE to be 1.
| |
| − |
| |
| − | ====<br /> Greater Than ====
| |
| − |
| |
| − | {|
| |
| − | |(> e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if e1 > e2 [> e3...], else FALSE.
| |
| − | |-
| |
| − | |''example:'' ||(> 7 4 6) evaluates to FALSE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> Greater Than or Equals ====
| |
| − |
| |
| − | {|
| |
| − | |(>= e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if e1 >= e2 [>= e3...], else FALSE.
| |
| − | |-
| |
| − | |''example:'' ||(>= 7 4 4) evaluates to TRUE.
| |
| − |
| |
| − | ====<br /> Less Than ====
| |
| − |
| |
| − | (< e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if e1 < e2 [< e3...], else FALSE.
| |
| − | |-
| |
| − | |''example:'' ||(< 2 4 5) evaluates to TRUE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> Less Than or Equals ====
| |
| − |
| |
| − | {|
| |
| − | |(<= e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if e1 <= e2 [<= e3...], else FALSE.
| |
| − | |-
| |
| − | |''example:'' ||(<= 7 8 7) evaluates to FALSE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> Is Equal To
| |
| − |
| |
| − | {|
| |
| − | |(== e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if e1 == e2 [== e3...], else FALSE.
| |
| − | |-
| |
| − | |''example:'' ||(== 1 TRUE 1) evaluates to TRUE.
| |
| − | |}
| |
| − |
| |
| − | '''Page 7'''
| |
| − |
| |
| − | ====<br /> Is Not Equal To ====
| |
| − |
| |
| − | {|
| |
| − | |(!= e1 e2 [e3...])|-
| |
| − | |evaluates to: ||TRUE if e1 != e2 [!= e3...], else FALSE.|-
| |
| − | |''example:'' ||( ! = 7 4 6) evaluates to TRUE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> AND ====
| |
| − |
| |
| − | {|
| |
| − | |(and e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if all the expressions are non-zero, else FALSE.|-
| |
| − | |''example:'' ||(and 7 4 6) evaluates to TRUE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> OR ====
| |
| − |
| |
| − | {|
| |
| − | |(or e1 e2 [e3...])
| |
| − | |-
| |
| − | |evaluates to: ||TRUE if any of the expressions are non-zero, else FALSE.|-
| |
| − | |''example:'' ||(or 3 0 2) evaluates to TRUE.
| |
| − | |}
| |
| − |
| |
| − | ====<br /> NOT ====
| |
| − |
| |
| − | (not el)|-
| |
| − | |evaluates to: ||TRUE if the expression is zero, else FALSE.|-
| |
| − | |''example:'' ||(not 6) evaluates to FALSE.
| |
| − | |}
| |
| − |
| |
| − | '''Page 8'''
| |
| − | ===<br /> 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 is an expression.
| |
| − |
| |
| − | (= v e) evaluates to v = e
| |
| − |
| |
| − | (+= v e) evaluates to v = v + e
| |
| − |
| |
| − | (-= v e) evaluates to v = v - e
| |
| − |
| |
| − | (*= v e) evaluates to v = v * e
| |
| − |
| |
| − | (/= v e) evaluates to v = v / e
| |
| − |
| |
| − | (|= v e) evaluates to v = v | e
| |
| − |
| |
| − | (&= v e) evaluates to v = v & e
| |
| − |
| |
| − | (^= v e) evaluates to v = v ^ e
| |
| − |
| |
| − | (>>= v e) evaluates to v = v >> e
| |
| − |
| |
| − | (<<= v e) evaluates to v = v << e
| |
| − |
| |
| − | (++ v) evaluates to v = v + 1
| |
| − |
| |
| − | (--v) evaluates to v = v - 1
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| − |
| |
| | | | |
| | | | |
Official SCI Documentation
The SCI language is an object-oriented language with a Lisp-like syntax. It is compiled by the sc compiler into p-machine code which is used by the interpreter, sci.exe. We will begin our discussion of the language with its basic Lisp-like characteristics, then go on to the object-oriented parts of the language. Like Lisp, SCI is based on parenthesized expressions which return values. An expression is of the form:
(procedure [parameter parameter...])
The parameters to a procedure may themselves be expressions to be evaluated, and may be nested until you lose track of the parentheses. Unlike Lisp, a procedure itself may not be the result of an evaluation. An example of an expression is:
(+ (-y 2) (/ x 3))
which would be written in infix notation as:
(y -2) + (x / 3)
All expressions are guaranteed to be evaluated from left to right. Thus,
(= x 4)
(= y (/ (+= x 4) ( / = x 2)))
will result in y = 2 and x = 4.
Comments in SCI begin with a semicolon and continue to the end of the line.
- Notes
Table of Contents
< Previous: Table of ContentsNext: Files >
