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Unevaluated[expr]

represents the unevaluated form of expr when it appears as the argument to a function.

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Unevaluated

Unevaluated[expr]

represents the unevaluated form of expr when it appears as the argument to a function.

Details

  • f[Unevaluated[expr]] effectively works by temporarily setting attributes so that f holds its argument unevaluated, then evaluating f[expr].

Examples

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Basic Examples  (1)

Feed an unevaluated expression to Length:

Wolfram Language code: Length[Unevaluated[5 + 6 + 7 + 8]]

Applications  (1)

Use HoldAll and Unevaluated to suppress evaluation of symbols wherever they would occur:

Wolfram Language code: SetAttributes[symbolLength, HoldAll]; symbolLength[s_Symbol] := StringLength[SymbolName[Unevaluated[s]]]

Find the length of a symbol's name even if it has a value:

Wolfram Language code: xyzzy = 42;
Wolfram Language code: symbolLength[xyzzy]

Properties & Relations  (3)

Unevaluated works only where it appears; it is not propagated:

Wolfram Language code: f[x_] := g[x]
Wolfram Language code: f[Unevaluated[1 + 1]]

Unevaluated stops Evaluate:

Wolfram Language code: Hold[Evaluate[Unevaluated[1 + 2]]]

Unevaluated inside a held function remains:

Wolfram Language code: SetAttributes[f, HoldAll]
Wolfram Language code: f[Unevaluated[1 + 2]]
Wolfram Research (1991), Unevaluated, Wolfram Language function, https://reference.wolfram.com/language/ref/Unevaluated.html.

Text

Wolfram Research (1991), Unevaluated, Wolfram Language function, https://reference.wolfram.com/language/ref/Unevaluated.html.

CMS

Wolfram Language. 1991. "Unevaluated." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Unevaluated.html.

APA

Wolfram Language. (1991). Unevaluated. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Unevaluated.html

BibTeX

@misc{reference.wolfram_2026_unevaluated, author="Wolfram Research", title="{Unevaluated}", year="1991", howpublished="\url{https://reference.wolfram.com/language/ref/Unevaluated.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_unevaluated, organization={Wolfram Research}, title={Unevaluated}, year={1991}, url={https://reference.wolfram.com/language/ref/Unevaluated.html}, note=[Accessed: 13-June-2026]}