In programming language theory, lazy evaluation or call-by-need is an evaluation strategy which delays the evaluation of an expression until its value is needed ( non-strict evaluation ) and which also avoids repeated evaluations ( sharing ).

This form of non-strict evaluation is also known as lazy evaluation and used in functional programming languages.

A non-strict form allows one exception to this format restriction for allowing the empty word ( epsilon, ε ) to be a member of the described language.

A non-strict programming language allows the user to define non-strict functions, and hence may allow lazy evaluation.

* All hardware architectures in common use are optimized for strict languages, so the best compilers for non-strict languages produce slower code than the best compilers for strict languages, with the notable exception of the Glasgow Haskell Compiler which outperforms many strict language compilers.

In many strict languages, some advantages of non-strict functions can be obtained through the use of macros or thunks.

The x87 registers form an 8-level deep non-strict stack structure ranging from ST ( 0 ) to ST ( 7 ) with registers that can be directly accessed by either operand, using an offset relative to the top, as well as pushed and popped.

Multiple granularity locking is usually used with non-strict two-phase locking to guarantee serializability.

In a non-strict functional programming language, strictness analysis refers to any algorithm used to prove the strictness of a function with respect to one or more of its arguments.

Strict programming languages are often associated with eager evaluation, and non-strict languages with lazy evaluation, but other evaluation strategies are possible in each case.

An open convex polytope is defined in the same way, with strict inequalities used in the formulas instead of the non-strict ones.

Different villages practice different marriage customs ( strict monogamy, non-strict monogamy, or polyandry ), worship different local " godlings ", and specialize in various local handcrafts and foodstuffs, but share the common values of the New Cretan civilization and devotion to the Triple Goddess.

In ( 2 ), inheritance descendant is meant in the non-strict sense – including the metaclass root itself.

* SASL ( programming language ), a non-strict functional programming language developed by David Turner in 1976

However, the possible absence of a center of symmetry not only moves the hydrogen atom off Af, but also allows the oxygen atoms to become nonequivalent, with Af at Af and Af at Af ( space group Af ), where Af represents the oxygens on one side of the Af layers and Af those on the other side.

This statement also allows the naming of the index words used by Aj.

GOTO also allows manufacturers to add equatorial tracking to mechanically simpler alt-azimuth telescope mounts, allowing them to produce an over all less expensive product.

It also allows most private litigants to settle their disputes in an amicable manner through discovery and pre-trial settlements in which non-contested facts are agreed upon and not dealt with during the trial process.

The Belgian Blue's meat cuts also have a lower collagen content, which allows the protein quality to be improved due to a higher yield of amino acids.

A short hitting action is not only useful for deception: it also allows the player to hit powerful strokes when he has no time for a big arm swing.

This approach also allows preserving the curve definition under all linear or perspective 2D and 3D transforms and projections.

In addition to allowing extra room for the passage of muscles to work the lower jaw, the zygomatic arch also allows for differentiation of separate muscle groups to be involved in biting and chewing.

Castle of the Winds also allows the player to restore saved games after dying.

The addition of the empty string allows the statement that the context sensitive languages are a proper superset of the context free languages, rather than having to make the weaker statement that all context free grammars with no → λ productions are also context sensitive grammars.

A keyset or chorded keyboard ( also called a chorded keyset, chord keyboard or chording keyboard ) is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a " chord " on a piano.

Because fly ash addition allows a lower concrete water content, early strength can also be maintained.

It also allows multiple types of memory to be used.

Direct fuel injection which can inject fuel only at the time of fuel ignition ( similar to a diesel engine ) is another recent development which also allows for higher compression ratios on gasoline engines.

Encapsulation increases chemical and thermal stability of carotene molecules ; it also allows their isolation and individual characterization.

Most file types also allocate a few bytes for metadata, which allows a file to carry some basic information about itself.

When a computer allows the use of folders, each file and folder has not only a name of its own, but also a path, which identifies the folder or folders in which a file or folder resides.

Liquid helium is also commonly used and allows for the lowest attainable temperatures to be reached.

Automatic lead selection or lead steering is also intended to improve efficiencies, both for inbound and outbound campaigns, whereby inbound calls are intended to quickly land with the appropriate agent to handle the task, whilst minimizing wait times and long lists of irrelevant options for people calling in, as well as for outbound calls, where lead selection allows management to designate what type of leads go to which agent based on factors including skill, socioeconomic factors and past performance and percentage likelihood of closing a sale per lead.

It also allows the crankshaft to be reground without re-hardening.

Like Edinburgh IMP it allows embedded assembler, and also offers good run-time checking and diagnostics.

The Church of Finland also allows prayer for same-sex couples.

The United Church of Canada also allows same-sex marriage, and views sexual orientation as a gift from God.

" It has also been implied, especially in the ' alternate future ' story Kingdom Come, that the Clark Kent persona is symbolic of the values taught to him by his wholesome Midwestern parents, the values he holds most dear: his instinctive knowledge of right and wrong that allows him to adopt his Superman persona, without being consumed by the moral implications of his actions ; Superman is the means through which he can bring this example to the world.

Cactus stems also store water, and are often ribbed or fluted, which allows them to expand and contract easily.

The most common logical connectives are binary connectives ( also called dyadic connectives ) which join two sentences which can be thought of as the function's operands.

The ancient Egyptians also used dyadic fractions in measurement, with denominators up to 1 / 64, using a notation based on the Eye of Horus ( see, e. g., Curtis ).

Note also that this explanation would predict a monadic effect, although weaker than the dyadic one.

* The additive group of the dyadic rational numbers, the rational numbers of the form a / 2 < sup > b </ sup >, is also locally cyclic – any pair of dyadic rational numbers a / 2 < sup > b </ sup > and c / 2 < sup > d </ sup > is contained in the cyclic subgroup generated by 1 / 2 < sup > max ( b, d )</ sup >.

However, dyadic operations such as FADD, FMUL, FCOM, and so on may either implicitly use the topmost st0 and st1, or it may use st0 together with an explicit memory operand or register ; the st0 register may thus be used as an accumulator ( i. e. as a combined destination and left operand ) and can also be exchanged with any of the eight stack registers using an instruction called FXCH stX ( codes D9C8 .. D9CF < sub > h </ sub >).

Resentment can also be generated by dyadic interactions, such as emotional rejection or denial by another person, deliberate embarrassment or belittling by another person, or ignorance, putting down, criticism, or scorn by another person.