Elements of a set are literals

In my context literals are strings. How can I describe that the set $A$ contains literals $L$ using set notation? Like this?

$$\text{ Literal } \mathcal L$$

$$A = \{x \mid x = \mathcal L \}$$

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What exactly are you trying to describe here? What set is $A$ supposed to be? – Chris Eagle Feb 3 at 19:48
That the set A contains literals L, and that these literals are lexical representations of values. – Inge Henriksen Feb 3 at 19:50
Is $\mathcal{L}$ the set of all "literals"? If so, one would express the fact that $A$ is a set of literals by writing $A \subseteq \mathcal{L}$ ($A$ is a subset of $\mathcal{L}$.) – Trevor Wilson Feb 3 at 20:11
What is a string, mathematically? Is it a finite sequence from some fixed alphabet? – Trevor Wilson Feb 3 at 20:12
If, say, $\Sigma$ denotes some character set, then $\Sigma^*$ is sometimes used to denote the set of finite strings of characters in $\Sigma$. So you could say $A \subseteq \Sigma^*$. – Trevor Wilson Feb 3 at 20:27