Identifiers

There are two kinds of identifiers in Grain—those that begin with an uppercase letter, and those that do not.

Uppercase identifiers

Identifers that start with an uppercase letter are used for the names of modules and concrete types. We call these tokens UIDENTs (Uppercase Identifiers).

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UIDENT = ['A'-'Z']['A'-'Z' 'a-z' '0'-'9' '_']* ;

A UIDENT starts with an uppercase letter A through Z, followed by any number of:

• Uppercase letters A through Z
• Lowercase letters a through z
• Digits 0 through 9
• Underscores

Lowercase identifiers

Identifers that don’t start with an uppercase letter are used for the names of new bindings, record fields, type variables, and more. We call these tokens LIDENTs (Lowercase Identifiers) though it should be noted that LIDENTs may also start with underscores.

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LIDENT = ['a-z' '_']['A'-'Z' 'a-z' '0'-'9' '_']* ;

An LIDENT starts with an underscore or a lowercase letter a through z, followed by any number of:

• Uppercase letters A through Z
• Lowercase letters a through z
• Digits 0 through 9
• Underscores