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Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 70 |
1 files changed, 69 insertions, 1 deletions
@@ -6607,6 +6607,7 @@ is the matching object. .SS Functions remq, remql and remqual +.TP Syntax: (remq <object> <list>) @@ -6750,7 +6751,74 @@ symbols, packages, or streams are equal if they are the same hash. Certain object types have a custom equal function. -.SS Arithmetic functions +, -, * +.SS Arithmetic functions +, - + +.TP +Syntax: + + (+ <number>*) + (- <number> <number>*) + (* <number>*) + +.TP +Description: + +The +, - and * functions perform addition, subtraction and multiplication, +respectively. Additionally, the - function performs additive inverse. + +The + function requires zero or more arguments. When called with no +arguments, it produces 0 (the identity element for adddition), otherwise it +produces the sum over all of the arguments. + +Similarly, the * function requires zero or more arguments. When called +with no arguments, it produces 1 (the identity element for multiplication). +Otherwise it produces of all the arguments. + +The semantics of - changes from subtraction to additive inverse +when there is only one argument. The argument is treated as a subtrahend, +against an implicit minuend of zero. When there are two or more +argument, the first one is the minuend, and the remaining are subtrahends. + +When there are three or more operands, these operations are performed as if by +binary operations, in a left-associative way. That is to say, (+ a b c) means +(+ (+ a b) c). The sum of a b is computed first, and then this is added to c. +Similarly (- a b c) means (- (- a b) c). First, b is subtracted from a, and +then c is subtracted from that result. + +The arithmetic inverse is performed as if it were subtraction from integer 0. +That is, (- x) means the same thing as (- 0 x). + +The operands of +, - and * can be characters, integers (fixnum and bignum), and +floats, in nearly any combination. + +If two operands have different types, then one of them is converted to the +type of the other, according to this ranking: character -> integer -> float. +For instance if one operand is integer, and the other float, the integer +is converted to a float. + +.TP +Restrictions: + +Characters are not considered numbers, and participate in these operations in +limited ways. Subtraction can be used to computed the displacement between the +Unicode values of characters, and an integer displacement can be added to a +character, or subtracted from a character. For instance (- #\e9 #\e0) is 9. +The Unicode value of a character C can be found using (- C #\ex0): the +displacement from the NUL character. + +Therefore: + +Two characters may not be added together. + +A character may not be subtracted from an integer (which also rules out +the possibility of computing the additive inverse of a character). + +A character operand may not be opposite to a floating point operand +in any operation. + +A character may not be an operand of multiplication. + +.SS Arithmetic function * .SS Arithmetic function /, trunc, mod |