Penlight

• GitHub Project
• Documentation

Contents

• Functions

Libraries

• pl
• pl.app
• pl.array2d
• pl.class
• pl.compat
• pl.comprehension
• pl.config
• pl.data
• pl.dir
• pl.file
• pl.func
• pl.import_into
• pl.input
• pl.lapp
• pl.lexer
• pl.luabalanced
• pl.operator
• pl.path
• pl.permute
• pl.pretty
• pl.seq
• pl.sip
• pl.strict
• pl.stringio
• pl.stringx
• pl.tablex
• pl.template
• pl.test
• pl.text
• pl.types
• pl.url
• pl.utils
• pl.xml

Classes

• pl.Date
• pl.List
• pl.Map
• pl.MultiMap
• pl.OrderedMap
• pl.Set

Manual

• Introduction
• Tables and Arrays
• Strings. Higher-level operations on strings.
• Paths and Directories
• Date and Time
• Data
• Functional Programming
• Additional Libraries
• Technical Choices

Examples

• seesubst.lua
• sipscan.lua
• symbols.lua
• test-cmp.lua
• test-data.lua
• test-listcallbacks.lua
• test-pretty.lua
• test-symbols.lua
• testclone.lua
• testconfig.lua
• testglobal.lua
• testinputfields.lua
• testinputfields2.lua
• testxml.lua
• which.lua

Module pl.types

Dealing with Detailed Type Information

Functions

is_callable (obj)	is the object either a function or a callable object?.
is_type (obj, tp)	is the object of the specified type?.
type (obj)	a string representation of a type.
is_integer (x)	is this number an integer?
is_empty (o, ignore_spaces)	Check if the object is "empty".
is_indexable (val)	is an object 'array-like'?
is_iterable (val)	can an object be iterated over with pairs?
is_writeable (val)	can an object accept new key/pair values?
to_bool (o[, true_strs[, check_objs]])	Convert to a boolean value.

Functions

is_callable (obj)

is the object either a function or a callable object?.

Parameters:

• obj Object to check.

is_type (obj, tp)

is the object of the specified type?. If the type is a string, then use type, otherwise compare with metatable.

NOTE: this function is imported from utils.is_type.

Parameters:

• obj An object to check
• tp The expected type

See also:

utils.is_type

type (obj)

a string representation of a type. For tables and userdata with metatables, we assume that the metatable has a _name field. If the field is not present it will return 'unknown table' or 'unknown userdata'. Lua file objects return the type 'file'.

Parameters:

• obj an object

Returns:

a string like 'number', 'table', 'file' or 'List'

is_integer (x)

is this number an integer?

Parameters:

• x a number

Returns:

boolean

Raises:

error if x is not a number

is_empty (o, ignore_spaces)

Check if the object is "empty". An object is considered empty if it is:

• nil
• a table without any items (key-value pairs or indexes)
• a string with no content ("")
• not a nil/table/string

Parameters:

• o The object to check if it is empty.
• ignore_spaces If the object is a string and this is true the string is considered empty if it only contains spaces.

Returns:

true if the object is empty, otherwise a falsy value.

is_indexable (val)

is an object 'array-like'? An object is array like if:

• it is a table, or
• it has a metatable with __len and __index methods

NOTE: since __len is 5.2+, on 5.1 is usually returns false for userdata

Parameters:

• val any value.

Returns:

true if the object is array-like, otherwise a falsy value.

is_iterable (val)

can an object be iterated over with pairs? An object is iterable if:

• it is a table, or
• it has a metatable with a __pairs meta method

NOTE: since __pairs is 5.2+, on 5.1 is usually returns false for userdata

Parameters:

• val any value.

Returns:

true if the object is iterable, otherwise a falsy value.

is_writeable (val)

can an object accept new key/pair values? An object is iterable if:

• it is a table, or
• it has a metatable with a __newindex meta method

Parameters:

• val any value.

Returns:

true if the object is writeable, otherwise a falsy value.

to_bool (o[, true_strs[, check_objs]])

Convert to a boolean value. True values are:

• boolean: true.
• string: 'yes', 'y', 'true', 't', '1' or additional strings specified by true_strs.
• number: Any non-zero value.
• table: Is not empty and check_objs is true.
• everything else: Is not nil and check_objs is true.

Parameters:

• o The object to evaluate.
• true_strs optional Additional strings that when matched should evaluate to true. Comparison is case insensitive. This should be a List of strings. E.g. "ja" to support German. (optional)
• check_objs True if objects should be evaluated. (optional)

Returns:

true if the input evaluates to true, otherwise false.