Thun/docs/reference/infra.md

Combinator Accept a quoted program and a list on the stack and run the program with the list as its stack. Does not affect the stack (below the list.) ... x y z [a b c] [Q] infra

## infra Combinator Accept a quoted program and a list on the stack and run the program with the list as its stack. Does not affect the stack (below the list.) ... x y z [a b c] [Q] infra

    c b a Q [z y x ...] swaack

Definition

[swons] [swaack] i [dip] [swaack]

... [a b c] [F] swons swaack [i] dip swaack
... [[F] a b c]       swaack [i] dip swaack

c b a [F]   [...] [i] dip swaack
c b a [F] i [...]         swaack
c b a  F    [...]         swaack
d e         [...]         swaack
... [e d]

Discussion

This is one of the more useful combinators. It allows a quoted expression to serve as a stack for a program, effectively running it in a kind of "pocket universe". If the list represents a datastructure then infra lets you work on its internal structure.

Crosslinks

swaack