SNOBOL4EXT(1) | CSNOBOL4B 2.1.3 | June 25, 2020

NAME

DESCRIPTION

ARRAY/TABLE access

Multiple ARRAY and/or TABLE index operations may appear in a row, without having to resort to use of the ELEMENT function, so long as no intervening spaces (or line continuations) appear.

Case folding

By default the compiler folds identifiers and directives to upper case, so programs can be entered in either case: see snobol4(1), -CASE in snobol4ctrl(1), &CASE in snobol4key(1).

Control lines

The following additional “control lines” are implemented: -CASE, -COPY, -ERROR, -NOERRORS, -EXECUTE, -NOEXECUTE, -HIDE, -INCLUDE, -LINE: See snobol4ctrl(1).

Functions

The following additional functions are implemented: ATAN(), BREAKX(), CHAR(), CHOP() COS(), DATE(), DELETE(), EXP(), FILE(), FILE_ABSPATH(), FILE_ISDIR() FREEZE(), FUNCTION(), HOST(), IO_FINDUNIT() LABEL(), LEQ(), LGE(), LLE(), LLT(), LN(), LNE(), LOG(), LPAD(), ORD(), RENAME(), REVERSE(), RPAD(), RSORT(), SET() SETEXIT(), SIN(), SORT(), SQRT(), SSET(), SUBSTR(), TAN(), THAW(), VDIFFER(): see snobol4func(1).

Keywords

The following additional keywords are implemented: &CASE, &DIGITS, &ERRTEXT &FILE, &GCTIME, &GTRACE &LASTFILE, &LASTLINE, &LCASE, &LINE, &MAXINT, &PARM, &PI, &STEXEC, &UCASE: see snobol4key(1).

REAL numbers in INTEGER contexts

REAL numbers (or strings convertible to REAL) are accepted in all contexts which previously required an INTEGER (or string convertible to INTEGER). Contexts include TABLE(), ITEM(), array indices, INPUT(), OUTPUT(), SET(), keyword values, CHAR(), RPAD(), LPAD(), FIELD(), COLLECT(), DUMP(), DUPL(), OPSYN(), SUBSTR().

Scientific notation

REAL number syntax has been expanded to allow exponents of the form: ANY('Ee') ('+' | '-' | ”) SPAN('0123456789'). Exponential format reals need not contain a decimal point.

SPITBOL operators

The SPITBOL scan (?) and assignment (=) operators have been added. A pattern match can appear within an expression, and returns the matched string as its value. Similarly assignment can appear in an expression, and returns the assigned value. An assignment after a scan (ie; STRING ? PATTERN = VALUE) performs a scan and replace. Assignment is right associative, and has the lowest precedence, while scan is left associative and has a precedence just higher than assignment.

The SPITBOL selection/alternative construction can be used in any expression. It consists of a comma separated list of expressions inside parentheses. The expressions are evaluated until one succeeds, and its value is returned. Abuse of this construction may result in incomprehensible code.

The type NUMERIC with CONVERT() and the removal of leading spaces from strings converted to numbers (implicitly or explicitly) are also legal when SPITBOL extensions are enabled. SPITBOL extensions can be enabled and disabled using the -PLUSOPS directive. -PLUSOPS 0 or -PLUSOPS disables SPITBOL operators, while -PLUSOPS n where n is a non-zero integer enables them. SPITBOL extensions are enabled by default.

TERMINAL I/O variable

The variable TERMINAL is associated with the standard error file descriptor for both input and output.

TRACE() function type argument

The second argument of the TRACE() function can be abbreviated to a single letter: C (CALL), F (FUNCTION), K (KEYWORD), L (LABEL), R (RETURN), or V (VALUE) as in Macro SPITBOL.

TRACE() of additional keywords

&ERRTEXT and &STFCOUNT can be traced.

Value TRACE() on pattern match assignments

variable changes by . and $ operators are visible via value trace.

BUGS

Group the keywords, control lines, functions, operators together!

SEE ALSO