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Differences to Prolog

PXL syntax is based on Prolog syntax; however, the overall effect is considerably different

Lists

In Prolog, list elements are separated by commas; in PXL they are separated by whitespace. (Commas can also be used, although whitespace is more idiomatic)

This also applies to term arguments

Strings and string interpolation

In Prolog, strings are actually lists of character codes, and are denoted using double quotes.

In PXL , double quotes denotes an interpolated atom

Punctuation

In Prolog, the end of a term is denoted using a period, '.'.

In PXL , there is no need to denote the end of a term; the syntax rules guarantee that this will be unambiguous

Extended operators

In Prolog you can extend the syntax by defining your own operators, declaring priority and infix vs prefixness; in PXL many operators have already been defined. See the section on operators for a full list



chris mungall 2006-02-09