Built-in functions
There are some builtin functions in addition to the type specific functions described in the Types chapter
Output
These functions control output from the script
The function takes an arbitrary number of arguments and outputs the result of to_str of each argument separated by a space to standard out.
print(1,2,[1]) # prints "1 2 [1]" to stdout
println
Identical to print, except it adds a newline character to the output
eprint
Identical to print, except it outputs to standard error
eprintln
Identical to eprint, except it adds a newline character to the output
Type functions
These functions help convert between and identify value types
to_str
The to_str converts its one argument into a string representation. For strings, it is the identity function. For Numbers, Lists, Tables and Process Results it is a JSON representation of the structure. For functions, it will return “«function»”
is_
The is_ functions are used to query the type of a value.
- is_number
- is_string
- is_list
- is_table
- is_process_result
- is_function
parse_number
Parses a number from a string
parse_number("1.42") # Returns the number value 1.42
JSON functions
Slash has native support for JSON
json_stringify
Creates a json representation of any slash value
json_stringify(4) # Returns the string "4"
json_stringify([2,3]) # Returns the string "[2,3]"
json_parse
Parses a json string into a slash value. Since there a no null values in slash a null in a json input file is converted to an empty table
json_parse("{\"a\": 6, \"b\": null) # Returns the table {"a" : 6, "b": {}}
Shell functions
These functions interacts with the execution environment
include
This function evaluates the provided script in the current scope. The argument is a string that will be resolved to a file name and that file will be loaded and interpreted in the current scope.
args
Zero argument function that returns the arguments to the script as a list. This function returns a copy of the formal arguments to the script. The first element is the script itself.
When being run with stdin as source, the list will be empty.
cwd
Zero argument function that return the current working directory
path_of_script
Zero argument function that returns the path of the current executing script. It returns the current working directory when input is received on stdin.
exit
Exits with the given exit code
exit(0)
lookup_env_var
Looks up an environment variable.
lookup_env_var("PATH") # returns the value of the environment variable PATH (corresponds to $PATH)
The function is similar to the $VAR notation but allows for dynamic variable lookup, as in
lookup_env_var("VA"+"R")