lazy(3o) [debian man page]
Lazy(3o) OCaml library Lazy(3o) NAME
Lazy - Deferred computations. Module Module Lazy Documentation Module Lazy : sig end Deferred computations. type 'a t = 'a lazy_t A value of type 'a Lazy.t is a deferred computation, called a suspension, that has a result of type 'a . The special expression syntax lazy (expr) makes a suspension of the computation of expr , without computing expr itself yet. "Forcing" the suspension will then compute expr and return its result. Note: lazy_t is the built-in type constructor used by the compiler for the lazy keyword. You should not use it directly. Always use Lazy.t instead. Note: Lazy.force is not thread-safe. If you use this module in a multi-threaded program, you will need to add some locks. Note: if the program is compiled with the -rectypes option, ill-founded recursive definitions of the form let rec x = lazy x or let rec x = lazy(lazy(...(lazy x))) are accepted by the type-checker and lead, when forced, to ill-formed values that trigger infinite loops in the garbage collector and other parts of the run-time system. Without the -rectypes option, such ill-founded recursive definitions are rejected by the type-checker. exception Undefined val force : 'a t -> 'a === force x forces the suspension x and returns its result. If x has already been forced, Lazy.force x returns the same value again with- out recomputing it. If it raised an exception, the same exception is raised again. Raise Undefined if the forcing of x tries to force x itself recursively. === val force_val : 'a t -> 'a force_val x forces the suspension x and returns its result. If x has already been forced, force_val x returns the same value again without recomputing it. Raise Undefined if the forcing of x tries to force x itself recursively. If the computation of x raises an exception, it is unspecified whether force_val x raises the same exception or Undefined . val lazy_from_fun : (unit -> 'a) -> 'a t lazy_from_fun f is the same as lazy (f ()) but slightly more efficient. val lazy_from_val : 'a -> 'a t lazy_from_val v returns an already-forced suspension of v This is for special purposes only and should not be confused with lazy (v) . val lazy_is_val : 'a t -> bool lazy_is_val x returns true if x has already been forced and did not raise an exception. OCamldoc 2012-06-26 Lazy(3o)
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MooseX::Has::Sugar(3pm) User Contributed Perl Documentation MooseX::Has::Sugar(3pm) NAME
MooseX::Has::Sugar - Sugar Syntax for moose 'has' fields VERSION
version 0.05070420 SYNOPSIS
Moose "has" syntax is generally fine, but sometimes one gets bothered with the constant typing of string quotes for things. The MooseX::Types module exists and in many ways reduces the need for constant string creation. Primary Benefits at a Glance Reduced Typing in "has" declarations. The constant need to type "=>" and '' is fine for one-off cases, but the instant you have more than about 4 attributes it starts to get annoying. More compact declarations. Reduces much of the redundant typing in most cases, which makes your life easier, and makes it take up less visual space, which makes it faster to read. No String Worries Strings are often problematic, due to white-space etc. Noted that if you do happen to mess them up, Moose should at least warn you that you've done something daft. Using this alleviates that worry. Before this Module. Classical Moose has foo => ( isa => 'Str', is => 'ro', required => 1, ); has bar => ( isa => 'Str', is => 'rw' lazy_build => 1, ); Lazy Evil way to do it: PLEASE DO NOT DO THIS has qw( foo isa Str is ro required 1 ); has qw( bar isa Str is rw lazy_build 1 ); With this module ( and with MooseX::Types ) use MooseX::Types::Moose qw( Str ); use MooseX::Has::Sugar; has foo => ( isa => Str, ro, required, ); has bar => ( isa => Str, rw, lazy_build, ); Or even use MooseX::Types::Moose qw( Str ); use MooseX::Has::Sugar; has foo => ( isa => Str, ro, required, ); has bar => ( isa => Str, rw, lazy_build, ); Alternative Forms Basic "is" Expansion Only ( using ::Sugar::Minimal instead ) use MooseX::Types::Moose qw( Str ); use MooseX::Has::Sugar::Minimal; has foo => ( isa => Str, is => ro, required => 1, ); has bar => ( isa => Str, is => rw, lazy_build => 1, ); Attribute Expansions with Basic Expansions ( Combining parts of this and ::Sugar::Minimal ) use MooseX::Types::Moose qw( Str ); use MooseX::Has::Sugar::Minimal; use MooseX::Has::Sugar qw( :attrs ); has foo => ( isa => Str, is => ro, required, ); has bar => ( isa => Str, is => rw, lazy_build, ); EXPORT GROUPS
:default Since 0.0300, this exports all our syntax, the same as ":attrs :isattrs". Primarily because I found you generally want all the sugar, not just part of it. This also gets rid of that nasty exclusion logic. :isattrs This exports "ro", "rw" and "bare" as lists, so they behave as stand-alone attrs like "lazy" does. has foo => ( required, isa => 'Str', ro, ); NOTE: This option is incompatible with ::Sugar::Minimal : "CONFLICTS" :attrs This exports "lazy" , "lazy_build" and "required", "coerce", "weak_ref" and "auto_deref" as subs that assume positive. has foo => ( required, isa => 'Str', ); NOTE: This option is incompatible with MooseX::Types and Moose's Type Constraints Module : "CONFLICTS" :is DEPRECATED. See ::Sugar::Minimal for the same functionality :allattrs DEPRECATED, just use ":default" or do use MooseX::Has::Sugar; EXPORTED FUNCTIONS
bare returns "('is','bare')" ro returns "('is','ro')" rw returns "('is','rw')" required returns "('required',1)" lazy returns "('lazy',1)" lazy_build returns "('lazy_build',1)" weak_ref returns "('weak_ref',1)" coerce returns "('coerce',1)" WARNING: Conflict with MooseX::Types and Moose::Util::TypeConstraints, see "CONFLICTS". auto_deref returns "('auto_deref',1)" CONFLICTS
MooseX::Has::Sugar::Minimal MooseX::Has::Sugar::Saccharin This module is not intended to be used in conjunction with ::Sugar::Minimal or ::Sugar::Saccharin We export many of the same symbols and its just not very sensible. MooseX::Types Moose::Util::TypeConstraints due to exporting the "coerce" symbol, using us in the same scope as a call to use MooseX::Types .... or use Moose::Util::TypeConstraints will result in a symbol collision. We recommend using and creating proper type libraries instead, ( which will absolve you entirely of the need to use MooseX::Types and MooseX::Has::Sugar(::*)? in the same scope ) AUTHOR
Kent Fredric <kentnl at cpan.org> COPYRIGHT AND LICENSE
This software is copyright (c) 2012 by Kent Fredric. This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself. perl v5.14.2 2012-02-12 MooseX::Has::Sugar(3pm)