Syntax of Expressions
Learn how the syntax of expressions can be defined and how the parsing process works.
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At its core, a program written in any textual programming language, such as OCaml, Java, Python is nothing more than a long string consisting of characters we enter with a keyboard. A string that makes up a valid program in one programming language might be considered invalid in another and vice versa. To illustrate, consider the following obscure string:
++++++++++[>+++++++>++++++++++>+++<<<-]>++.>+.+++++++
..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.
Obviously, its not a valid OCaml program.
The OCaml compiler will reject that string with a syntax error message.
Yet, it is a valid Hello World program according to the esoteric programming language Brainfuck.
Conversely, the string 1 + 2 is a perfectly valid OCaml program, but the Brainfuck compiler bluntly rejects it as invalid.
The set of rules that define what input strings are considered valid programs is called the syntax ...