Problem Statement

Create a function, compose,   whose two arguments   f   and   g,   are both functions with one argument.

The result of compose is to be a function of one argument, (lets call the argument   x),   which works like applying function   f   to the result of applying function   g   to   x.

Reference: Function composition Hint: In some languages, implementing compose correctly requires creating a closure.

Let's start with the solution:

: compose ( xt1 xt2 -- xt3 )
  >r >r :noname
     r> compile,
     r> compile,
     postpone ;
;

' 2* ' 1+ compose  ( xt )
3 swap execute .   \ 7