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Evaluate[expr]

causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.

Details
Details and Options Details and Options
Examples  
Basic Examples  
Scope  
Applications  
Properties & Relations  
Possible Issues  
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Evaluate

Evaluate[expr]

causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.

Details

  • You can use Evaluate to override HoldFirst etc. attributes of built‐in functions.
  • Evaluate only overrides HoldFirst etc. attributes when it appears directly as the head of the function argument that would otherwise be held. »

Examples

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Basic Examples  (1)

Evaluate inside a Hold:

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

Scope  (1)

Evaluate works for arguments of any symbol with attributes HoldAll, HoldFirst, or HoldRest:

Wolfram Language code: Attributes[Attributes]

Since Attributes is HoldAll, use Evaluate to find the properties of the value of x:

Wolfram Language code: x = Plus;
Wolfram Language code: {Attributes[x], Attributes[Evaluate[x]]}

Applications  (3)

Unprotect a system symbol to make a definition for it:

Wolfram Language code: protected = Unprotect[Sqrt]
Wolfram Language code: Sqrt[x_ ^ 2] := x

Restore protection:

Wolfram Language code: Protect[Evaluate[protected]]

Force evaluation of the right-hand side of a delayed definition:

Wolfram Language code: Expand[(1 + x) ^ 3]
Wolfram Language code: f[x_] := Evaluate[%]
Wolfram Language code: Definition[f]

Build a function from an expression:

Wolfram Language code: ch = ChebyshevT[5, x]
Wolfram Language code: Function[x, Evaluate[ch]]
Wolfram Language code: %[10]

Properties & Relations  (3)

Evaluate does not work inside functions with attribute HoldAllComplete:

Wolfram Language code: HoldComplete[Evaluate[1 + 2]]

Use Unevaluated to temporarily treat a function as if it were HoldAll:

Wolfram Language code: Length[Unevaluated[1 + 2 + 3]]
Wolfram Language code: Length[1 + 2 + 3]

Evaluate does not work inside Unevaluated:

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

Possible Issues  (1)

Evaluate works only on the first level, directly inside a held function:

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

Text

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

CMS

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

APA

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

BibTeX

@misc{reference.wolfram_2026_evaluate, author="Wolfram Research", title="{Evaluate}", year="1991", howpublished="\url{https://reference.wolfram.com/language/ref/Evaluate.html}", note=[Accessed: 13-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_evaluate, organization={Wolfram Research}, title={Evaluate}, year={1991}, url={https://reference.wolfram.com/language/ref/Evaluate.html}, note=[Accessed: 13-June-2026]}