output formatting - Question about evaluation control

I want to make a function that takes a function as a parameter and prints an integral with the function inside. I've tried this:

L[f_, a_, b_] := HoldForm[Integrate[f[x], {x, a, b}]]

L[E^-Sqrt[#] &, 0, 1]

But it gives me this:

$$\int_0^1 \left(e^{-\sqrt{\text{#1}}}\text{&}\right)[x] \, dx$$

I want the integrand to look normal, that's all, so I want the variable x to be substituted inside it, but not evaluated any further. Is this possible?

Answer

This works nicely:

L[f_, a_, b_] := HoldForm[Integrate[#, {\[FormalX], a, b}]] &[f[\[FormalX]]]

Note that I used \[FormalX] to prevent conflicts with the usual x, which may have had a previous definition. Try L[E^-Sqrt[#] &, 0, 1] with this definition:

example

Comments

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