`(! . exe) -> any`

- Low level breakpoint function: The current execution environment is saved
and the I/O channels are redirected to the console. Then
`exe`

is displayed, and a read-eval-print-loop is entered (with`!`

as its prompt character), to evaluate expressions and examine the current program environment. An empty input line terminates the read-eval-print-loop, the environment and I/O channels are restored, and the result of`exe`

is returned.`!`

is normally inserted into existing programs with the`debug`

function. See also`e`

,`^`

and`*Dbg`

.`: (de foo (N) (and (println 1) (! println N) (println 2))) -> foo : (foo 7) 1 # Executed '(println 1)' (println N) # Entered breakpoint ! N # Examine the value of 'N' -> 7 ! (e) # Evaluate '^', i.e. (println N) 7 -> 7 ! (e @) # Evaluate '@' -> the result of '(println 1)' -> 1 ! # Empty line: continue 7 # Executed '(println N)' 2 # Executed '(println 2)' -> 2`

`($ sym|lst lst . prg) -> any`

- Low level trace function: The first argument
`sym|lst`

is printed to the console with a proper indentation, followed by a colon`:`

. If a function is traced, the first argument is the function symbol, else if a method is traced, it is a cons pair of message and class. The second argument`lst`

should be a list of symbols, identical to the function's argument list. The current values of these symbols are printed, followed by a newline. Then`prg`

is executed, and its return value printed in a similar way (this time with an equals sign`=`

instead of a colon) and returned.`$`

is normally inserted into existing programs with the`trace`

function.`: (de foo (A B) ($ foo (A B) (* A B))) -> foo : (foo 3 4) foo : 3 4 # Function entry, arguments 3 and 4 foo = 12 # Function exit, return value 12 -> 12`

`($dat 'sym1 ['sym2]) -> dat`

- Converts a string
`sym1`

in ISO format to a`date`

, optionally using a delimiter character`sym2`

. See also`dat$`

,`$tim`

,`strDat`

and`expDat`

.`: ($dat "20070601") -> 733134 : ($dat "2007-06-01" "-") -> 733134`

`($tim 'sym) -> tim`

- Converts a string to a
`time`

. The minutes and seconds are optional and default to zero. See also`tim$`

and`$dat`

.`: (time ($tim "10:57:56")) -> (10 57 56) : (time ($tim "10:57")) -> (10 57 0) : (time ($tim "10")) -> (10 0 0)`

`(% 'num ..) -> num`

- Returns the remainder from the divisions of successive
`num`

arguments. The sign of the result is that of the first argument. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`/`

and`*/`

.`: (% 17 5) -> 2 : (% -17 5) # Sign is that of the first argument -> -2 : (% 5 2) -> 1 : (% 15 10) -> 5 : (% 15 10 2) # (% 15 10) -> 5, then (% 5 2) -> 1 -> 1`

`(& 'num ..) -> num`

- Returns the bitwise
`AND`

of all`num`

arguments. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`|`

,`x|`

and`bit?`

.`: (& 6 3) -> 2 : (& 7 3 1) -> 1`

`(* 'num ..) -> num`

- Returns the product of all
`num`

arguments. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`/`

,`*/`

,`+`

and`-`

.`: (* 1 2 3) -> 6 : (* 5 3 2 2) -> 60`

`(** 'num1 'num2) -> num`

- Integer exponentiation: Returns
`num1`

to the power of`num2`

.`: (** 2 3) -> 8 : (** 100 100) -> 10000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000000000000000000000000000000000000000 00000000000000000000000000000000000000000000`

`(*/ 'num1 ['num2 ..] 'num3) -> num`

- Returns the product of
`num1`

and all following`num2`

arguments, divided by the`num3`

argument. The result is rounded to the nearest integer value. When one of the arguments evaluates to`NIL`

, it is returned immediately. Note that`*/`

is especially useful for fixed point arithmetic, by multiplying with (or dividing by) the scale factor. See also`*`

,`/`

,`+`

,`-`

and`sqrt`

.`: (*/ 3 4 2) -> 6 : (*/ 1234 2 10) -> 247 : (*/ 100 6) -> 17 : (scl 2) -> 2 : (format (*/ 3.0 1.5 1.0) *Scl) -> "4.50" : (scl 20) -> 20 : (format (*/ 9.9 9.789 9.56789 `(* 1.0 1.0)) *Scl) -> "927.23474457900000000000"`

`(+ 'num ..) -> num`

- Returns the sum of all
`num`

arguments. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`inc`

,`-`

,`*`

,`/`

and`*/`

.`: (+ 1 2 3) -> 6`

`(++ var) -> any`

- Pops the first element (CAR) from the stack in
`var`

.`(++ Lst)`

is equivalent to`(pop 'Lst)`

. See also`pop`

. `(- 'num ..) -> num`

- Returns the difference of the first
`num`

argument and all following arguments. If only a single argument is given, it is negated. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`dec`

,`+`

,`*`

,`/`

and`*/`

.`: (- 7) -> -7 : (- 7 2 1) -> 4`

`(-> any [cnt]) -> any`

- Searches for the value of
`any`

(typically a Pilog variable, or an expression of variables) at top level (or level`cnt`

) in the current environment. See also`prove`

and`unify`

.`: (? (append (1 2 3) (4 5 6) @X) (^ @ (println 'X '= (-> @X)))) X = (1 2 3 4 5 6) @X=(1 2 3 4 5 6) -> NIL`

`(/ 'num ..) -> num`

- Returns the first
`num`

argument successively divided by all following arguments. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`*`

,`*/`

,`%`

,`+`

and`-`

.`: (/ 12 3) -> 4 : (/ 60 -3 2 2) -> -5`

`(: sym|0 [sym1|cnt ..]) -> any`

- Fetches a value
`any`

from the properties of a symbol, or from a list, by applying the`get`

algorithm to`This`

and the following arguments. Used typically in methods or`with`

bodies.`(: ..)`

is equivalent to`(; This ..)`

. See also`;`

,`=:`

and`::`

.`: (put 'X 'a 1) -> 1 : (with 'X (: a)) -> 1`

`(:: sym [sym1|cnt .. sym2]) -> var`

- Fetches a property for a property key
`sym`

or`sym2`

from a symbol. That symbol is`This`

(if no other arguments are given), or a symbol found by applying the`get`

algorithm to`This`

and the following arguments. The property (the cons pair, not just its value) is returned, suitable for direct (destructive) manipulations with functions expecting a`var`

argument. Used typically in methods or`with`

bodies. See also`=:`

,`prop`

and`:`

.`: (with 'X (=: cnt 0) (inc (:: cnt)) (: cnt)) -> 1`

`(; 'sym1|lst [sym2|cnt ..]) -> any`

- Fetches a value
`any`

from the properties of a symbol, or from a list, by applying the`get`

algorithm to`sym1|lst`

and the following arguments. See also`:`

,`=:`

and`::`

.`: (put 'A 'a 1) -> 1 : (put 'A 'b 'B) -> B : (put 'B 'c 7) -> 7 : (; 'A a) -> 1 : (; 'A b c) -> 7`

`(< 'any ..) -> flg`

- Returns
`T`

when all arguments`any`

are in strictly increasing order. See also Comparing.`: (< 3 4) -> T : (< 'a 'b 'c) -> T : (< 999 'a) -> T`

`(<= 'any ..) -> flg`

- Returns
`T`

when all arguments`any`

are in strictly non-decreasing order. See also Comparing.`: (<= 3 3) -> T : (<= 1 2 3) -> T : (<= "abc" "abc" "def") -> T`

`(<> 'any ..) -> flg`

- Returns
`T`

when not all`any`

arguments are equal (structure equality).`(<> 'any ..)`

is equivalent to`(not (= 'any ..))`

. See also Comparing.`: (<> 'a 'b) -> T : (<> 'a 'b 'b) -> T : (<> 'a 'a 'a) -> NIL`

`(= 'any ..) -> flg`

- Returns
`T`

when all`any`

arguments are equal (structure equality). See also Comparing.`: (= 6 (* 1 2 3)) -> T : (= "a" "a") -> T : (== "a" "a") -> T : (= (1 (2) 3) (1 (2) 3)) -> T`

`(=0 'any) -> 0 | NIL`

- Returns
`0`

when`any`

is a number with value zero. See also`n0`

,`lt0`

,`le0`

,`ge0`

,`gt0`

and`=1`

.`: (=0 (- 6 3 2 1)) -> 0 : (=0 'a) -> NIL`

`(=1 'any) -> 1 | NIL`

- Returns
`1`

when`any`

is a number with value one. See also`=0`

.`: (=1 (- 6 3 2)) -> 1 : (=1 'a) -> NIL`

`(=: sym|0 [sym1|cnt .. sym2|0] 'any)`

- Stores a new value
`any`

for a property key`sym`

or`sym2`

(or in the symbol value for zero) in a symbol. That symbol is`This`

(if no other arguments are given), or a symbol found by applying the`get`

algorithm to`This`

and the following arguments. Used typically in methods or`with`

bodies. See also`put`

,`:`

and`::`

.`: (with 'X (=: a 1) (=: b 2)) -> 2 : (get 'X 'a) -> 1 : (get 'X 'b) -> 2`

`(== 'any ..) -> flg`

- Returns
`T`

when all`any`

arguments are the same (pointer equality). See also`n==`

and Comparing.`: (== 'a 'a) -> T : (== 'NIL NIL (val NIL) (car NIL) (cdr NIL)) -> T : (== (1 2 3) (1 2 3)) -> NIL`

`(==== ['sym ..]) -> NIL`

- Close the current transient scope by clearing the transient index. All
transient symbols become hidden and inaccessible by the reader. Then any
optional
`sym`

arguments are (re-)inserted into the transient index. See also`extern`

and`intern`

.`: (setq S "abc") # Read "abc" -> "abc" : (== S "abc") # Read again, get the same symbol -> T : (====) # Close scope -> NIL : (== S "abc") # Read again, get another symbol -> NIL`

`(=T 'any) -> flg`

- Returns
`T`

when`any`

is the symbol`T`

.`(=T X)`

is equivalent to`(== T X)`

. See also nT.`: (=T 0) -> NIL : (=T "T") -> NIL : (=T T) -> T`

`(> 'any ..) -> flg`

- Returns
`T`

when all arguments`any`

are in strictly decreasing order. See also Comparing.`: (> 4 3) -> T : (> 'A 999) -> T`

`(>= 'any ..) -> flg`

- Returns
`T`

when all arguments`any`

are in strictly non-increasing order. See also Comparing.`: (>= 'A 999) -> T : (>= 3 2 2 1) -> T`

`(>> 'cnt 'num) -> num`

- Shifts right the
`num`

argument by`cnt`

bit-positions. If`cnt`

is negative, a corresponding left shift is performed.`: (>> 1 8) -> 4 : (>> 3 16) -> 2 : (>> -3 16) -> 128 : (>> -1 -16) -> -32`

`(? [sym ..] [pat 'any ..] . lst) -> flg`

- Top-level function for interactive Pilog
queries.
`?`

is a non-evaluating front-end to the`query`

function. It displays each result, waits for console input, and terminates when a non-empty line is entered. If a preceding list of (non-pattern-) symbols is given, they will be taken as rules to be traced by`prove`

. The list of variable/value pairs is passed to`goal`

for an initial Pilog environment. See also`pilog`

and`solve`

.`: (? (append (a b c) (d e f) @X)) @X=(a b c d e f) -> NIL : (? (append @X @Y (a b c))) @X=NIL @Y=(a b c) @X=(a) @Y=(b c) @X=(a b) @Y=(c) @X=(a b c) @Y=NIL -> NIL : (? (append @X @Y (a b c))) @X=NIL @Y=(a b c). # Stopped -> NIL : (? append (append @X @Y (a b c))) # Trace 'append' 1 (append NIL (a b c) (a b c)) @X=NIL @Y=(a b c) 2 (append (a . @X) @Y (a b c)) 1 (append NIL (b c) (b c)) @X=(a) @Y=(b c). # Stopped -> NIL`

`@`

- Holds the result of the last top level expression in the current
read-eval-print loop, or the result of the conditional expression during the
evaluation of flow functions (see
`@ Result`

). When`@`

is used as a formal parameter in lambda expressions, it denotes a variable number of evaluated arguments. `@@`

- Holds the result of the second last top level expression in the current
read-eval-print loop (see
`@ Result`

). Some functions store a secondary return value in`@@`

. `@@@`

- Holds the result of the third last top level expression in the current
read-eval-print loop (see
`@ Result`

). `^`

- Holds the currently executed expression during a breakpoint or an error. See
also
`debug`

,`!`

,`e`

and`*Dbg`

.`: (* (+ 3 4) (/ 7 0)) !? (/ 7 0) Div/0 ? ^ -> (/ 7 0)`

`(| 'num ..) -> num`

- Returns the bitwise
`OR`

of all`num`

arguments. When one of the arguments evaluates to`NIL`

, it is returned immediately. See also`x|`

,`&`

and`bit?`

.`: (| 1 2) -> 3 : (| 1 2 4 8) -> 15`