Quotations

Quotations are the general term for anonymous functions or lambdas. They denote a snippet of code which can be executed later. Their exact syntax varies by language. For example, Factor denotes quotations using square-brackets. Whereas, Tal and Postscript denote them using curly-brackets. Regardless of syntax, they are core to constructing higher-order functions in concatenative languages.

Higher-Order Function

A higher-order function is an operation that utilize other functions as inputs or create new functions as outputs. This feature is leverage by a core utility of concatenative programming: combinators. They enable a programmer to name code not values.

Factor

{ 1 2 3 4 } [ sq ] map 

Kitten

// [1, 4, 9, 16]
[1, 2, 3, 4] { dup (*) } map

Tal

Uxntal has no built-in map, see implementation.

{ 01 02 03 04 } { DUP MUL JMP2r } map

Uxntal can also quote single opcodes:

( to quote ) LIT ADD ( to unquote ) #00 STR

Mirth

1 2 3 4 L4 [ dup * ] map

Mirth has syntactic sugar that lets you write a quotation as an argument to the higher-order word, so a more idiomatic way to write this is:

1 2 3 4 L4 map(dup *)

Titan

Titan does not have a built in ForAll function, but it is implemented in std.quote.

[1 2 3 4] [: ×] ∀