Singular Expression (expr)

A Singular Expression is either an ID, acting as a placeholder for expression, an INTLIT, a STRLIT enclosed in quotes, a Conditional (cnd), or an Application (app).

An Expression can be part of a Compound Expression (compoundexpr).

expr:

_images/expr.png
expr ::= ID
       | INTLIT
       | '"' STRLIT '"'
       | cnd
       | app

References:

ID:
An ID is a regular string beginning with a letter and containing letters, numbers, or the symbols -, _, or . and not being a keyword.
INTLIT:
An INTLIT is an integer literal either being a single-digit number from 0 to 9 or a multiple-digit number starting with a digit from 1 to 9 and containing digits from 0 to 9. An INTLIT can be negative with a leading -.
STRLIT:
A STRLIT is a string literal containing any symbol except a ”.