With

Substitutes fixed values into an expression before evaluating it.

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With({x = x0, y = y0, ...}, body)

body

with every

x

replaced by its (already evaluated)

x0

, then evaluated.

Typed signatures

Type	Package	Applies
`(any, any) -> any`	`combinatorics`	always

Domain: Collections

Details

The bindings are simultaneous, not sequential — a later binding's value expression cannot see an earlier one in the same $With$ ; each is computed against the surrounding context alone. Use nested $With$ for one binding to see the previous.
A binding list is $\{x = x0, y = y0, ...\}$ : as MathJSON, $[List, [Equal, x, x0], ...]$ — = parses to $Equal$ , not to compute-engine's own $Assign$ .
Unlike Module, $With$ introduces no fresh variable — it is pure substitution, so a name used as an $x$ never shadows an outer binding beyond the substituted occurrences in $body$ itself.

Examples

Basic #

substitute a fixed value

\mathrm{With}(\bigl\lbrack x=3\bigr\rbrack, xx)

Out

9

Scope #

several bindings at once

\mathrm{With}(\begin{cases}x=2\\y=5\end{cases}, x+y)

Out

7

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