$nl
"Coming back to the example in the beginning of this article, the following series of steps occurs as the code is evaluated:"
{ $table
- { "Action" "Stack contents" }
+ { { $strong "Action" } { $strong "Stack contents" } }
{ "10 is pushed on the stack." { $snippet "10" } }
- { { "The " { $link sq } " word is executed. It pops one input from the stack - the integer 10 - and squares it, pushing the result." } { $snippet "100" } }
+ { { "The " { $link sq } " word is executed. It pops one input from the stack (the integer 10) and squares it, pushing the result." } { $snippet "100" } }
{ { "5 is pushed on the stack." } { $snippet "100 5" } }
- { { "The " { $link - } " word is executed. It pops two inputs from the stack - the integers 100 and 5 - and subtracts 5 from 100, pushing the result." } { $snippet "95" } }
- { { "The " { $link . } " word is executed. It pops one input from the stack - the integer 95 - and prints it in the listener's output area." } { } }
+ { { "The " { $link - } " word is executed. It pops two inputs from the stack (the integers 100 and 5) and subtracts 5 from 100, pushing the result." } { $snippet "95" } }
+ { { "The " { $link . } " word is executed. It pops one input from the stack (the integer 95) and prints it in the listener's output area." } { } }
}
"Factor supports many other data types:"
{ $code
"\"character strings\""
"{ 1 2 3 }"
"! by the way, this is a comment"
- "#! and so is this"
}
{ $references
{ "Factor's syntax can be extended, the parser can be called reflectively, and the " { $link . } " word is in fact a general facility for turning almost any object into a form which can be parsed back in again. If this interests you, consult the following sections:" }
$nl
"To run a script, simply pass it as an argument to the Factor executable:"
{ $code "./factor cleanup.factor" }
+"To test a script in the listener, you can use " { $link run-file } "."
+$nl
"The script may access command line arguments by inspecting the value of the " { $link command-line } " variable. It can also get its own path from the " { $link script } " variable."
{ $heading "Example: ls" }
"Here is an example implementing a simplified version of the Unix " { $snippet "ls" } " command in Factor:"
{ $code
- """USING: command-line namespaces io io.files
+ "USING: command-line namespaces io io.files
io.pathnames tools.files sequences kernel ;
command-line get [
- current-directory get directory.
+ \".\" directory.
] [
dup length 1 = [ first directory. ] [
- [ [ nl write ":" print ] [ directory. ] bi ] each
+ [ [ nl write \":\" print ] [ directory. ] bi ] each
] if
-] if-empty"""
+] if-empty"
}
"You can put it in a file named " { $snippet "ls.factor" } ", and then run it, to list the " { $snippet "/usr/bin" } " directory for example:"
{ $code "./factor ls.factor /usr/bin" }
{ $heading "Example: grep" }
"The following is a more complicated example, implementing something like the Unix " { $snippet "grep" } " command:"
-{ $code """USING: kernel fry io io.files io.encodings.ascii sequences
+{ $code "USING: kernel fry io io.files io.encodings.ascii sequences
regexp command-line namespaces ;
IN: grep
ascii [ grep-lines ] with-file-reader ;
: grep-usage ( -- )
- "Usage: factor grep.factor <pattern> [<file>...]" print ;
+ \"Usage: factor grep.factor <pattern> [<file>...]\" print ;
command-line get [
grep-usage
] [
[ grep-file ] with each
] if-empty
-] if-empty""" }
+] if-empty" }
"You can run it like so,"
{ $code "./factor grep.factor '.*hello.*' myfile.txt" }
"You'll notice this script takes a while to start. This is because it is loading and compiling the " { $vocab-link "regexp" } " vocabulary every time. To speed up startup, load the vocabulary into your image, and save the image:"
{ $code "USE: regexp" "save" }
"Now, the " { $snippet "grep.factor" } " script will start up much faster. See " { $link "images" } " for details."
{ $heading "Executable scripts" }
-"It is also possible to make executable scripts. A Factor file can begin with a comment like the following:"
-{ $code "#! /usr/bin/env factor" }
+"It is also possible to make executable scripts. A Factor file can begin with a 'shebang' like the following:"
+{ $code "#!/usr/bin/env factor" }
"If the text file is made executable, then it can be run, assuming the " { $snippet "factor" } " binary is in your " { $snippet "$PATH" } "."
-$nl
-"The space between " { $snippet "#!" } " and " { $snippet "/usr/bin/env" } " is necessary, since " { $link POSTPONE: #! } " is a parsing word, and a syntax error would otherwise result."
{ $references
{ }
- "cli"
+ "command-line"
"cookbook-application"
"images"
} ;