Page "Functional programming" Paragraph 6

Information Processing Language ( IPL ) is sometimes cited as the first computer-based functional programming language.

It is an assembly-style language for manipulating lists of symbols.

It does have a notion of " generator ", which amounts to a function accepting a function as an argument, and, since it is an assembly-level language, code can be used as data, so IPL can be regarded as having higher-order functions.

However, it relies heavily on mutating list structure and similar imperative features.