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Glossary

Source: vignettes/Glossary.Rmd
Glossary.Rmd

You can list all the installed words in froth with the WORDS word, or use froth.dictionary() from R. The following is all the words referenced in the previous chapters.

  • <NUMBER> ( -- n ) : pushes a number onto the stack
  • emit ( n -- ) : prints the top number of the stack, interpreting as ASCII
  • cr ( -- ): prints a new line
  • ." xxx" ( -- ): prints xxx on the terminal. Note that " terminates the string.
  • : xxx yyy ; ( -- ) : defines a word xxx comprised of words yyy
  • FORGET xxx ( -- ): removes the current word xxx. If xxx had a previous definition it reverts to that previous value, and otherwise the word is removed.
  • + (a b -- n): adds a+b
  • * (a b -- n): multiplies a*b
  • . (n -- ): pops the top element of stack and prints it
  • clear ( x1 x2 ... -- ): removes all elements of the stack
  • reset ( -- ): reset froth to defaults (wipe all user definitions, reinitialize all built-in definitions, reset all stacks)
  • / ( a b -- n ): division (5 2 / => 2.5)
  • %/% ( a b -- n): integer division (5 2 %/% => 2)
  • mod ( a b -- rem ): remainder when dividing a / b
  • /mod ( a b -- rem quot ): integer divides a %/% b, pushes the remainder and then the quotient
  • ^ ( a b -- n ): raises a^b
  • negate ( a -- n ): negates a
  • abs ( a -- n ): takes the absolute value of a
  • min ( a b -- min ): pushes min(a,b)
  • max ( a b -- max ): pushes max(a,b)
  • sqrt ( a -- root ): pushes sqrt(a)
  • SWAP ( a b -- b a ): swap top two stack elements
  • DUP ( n -- n n ): duplicate the top stack element
  • OVER ( a b -- a b a ): duplicate the second element to the top of the stack
  • ROT ( a b c -- b c a ): rotate the third item to the top
  • DROP ( n -- ): discard the top element of the stack
  • .S ( -- ): print out the contents of the stack
  • 2SWAP ( a b c d -- c d a b ): swap the top two pairs
  • 2DUP ( a b -- a b a b ): duplicate the top pair
  • 2OVER ( p1 p2 -- p1 p2 p1 ): duplicate the second pair (p1) to the top
  • 2DROP ( a b -- ): discard the top pair
  • >R ( n -- ): moves the value on the parameter stack to the return stack
  • R> ( -- n ): moves the value on the return stack to the parameter stack
  • R@ ( -- n ): copies the value on the return stack to the parameter stack
  • 1+ ( n1 -- n2 ): adds 1
  • 1- ( n1 -- n2 ): subtracts 1
  • 2+ ( n1 -- n2 ): adds 2
  • 2- ( n1 -- n2 ): subtracts 2
  • 2* ( n1 -- n2 ): multiplies by 2
  • 2/ ( n1 -- n2 ): divides by 2
  • */ ( a b c -- n ): pushes (a*b) / c
  • */mod ( a b c -- rem quot ): pushes the remainder and quotient of (a*b) %/% c
  • if: if top of stack is TRUE, executes. Else jumps to the next else or then block.
  • else: executes commands until then only if the preceding if did not execute.
  • then: terminates an if or if...else block.
  • \: signals to the interpreter that you’re making a newline without running commands
  • =: are the top two elements equal?
  • <: is the top element greater than the first?
  • >: is the top element less than the first?
  • <>: are the top two elements not equal?
  • 0=: is the top element zero?
  • 0<: is the top element greater than zero?
  • 0>: is the top element less than zero?
  • <=: is top element greater than or equal to the second?
  • >=: is top element less than or equal to the second?
  • AND: push TRUE if the top two elements are both TRUE
  • OR: push TRUE if at least one of the top two elements are TRUE
  • XOR: push TRUE if exactly one of the top two elements is TRUE
  • NOT: push TRUE if the top element is FALSE and vice-versa
  • ?DUP: duplicate top value if it is nonzero
  • ABORT": abort if top value true, print error message (terminated by ")
  • DO ( end start -- ): starts a definite loop from start to end
  • LOOP ( -- ): increments the loop counter by 1
  • +LOOP ( n -- ): increments the loop counter by n
  • I ( -- n ): copies the current loop counter to the stack
  • J ( -- n ): copies the enclosing loop’s counter to the stack
  • K ( -- n ): copies the enclosing loop’s enclosing loop’s counter to the stack
  • BEGIN ( -- ): starts an indefinite loop
  • AGAIN ( -- ): returns to BEGIN
  • WHILE ( flag -- ): if flag, continue; else jump to after REPEAT
  • REPEAT ( -- ): returns to BEGIN following WHILE
  • LEAVE ( -- ): leave the current loop immediately
  • VARIABLE xxx: creates a variable named xxx
  • ! ( n addr -- ): stores the value n at address addr
  • @ ( addr -- n ): copies the value at addr to the stack
  • ? ( addr -- ): prints the value of addr
  • +! ( n addr -- ): adds the value n to the value at addr
  • CONSTANT xxx (n -- ): creates a constant called xxx that stores n; xxx returns n when called
  • ALLOT ( addr ncells -- ): allocates ncells cells at addr
  • CREATE xxx y1 , y2 , ... yn ,: creates an array xxx with values y1, y2, ... yn
  • CELLS ( n -- ): creates a memory address offset for arrays
  • FILL ( addr ncells val -- ): fills ncells cells of memory beginning at addr with val
  • ERASE ( addr ncells -- ): fills ncells cells of memory beginning at addr with 0
  • REALLOT ( addr ncells -- ): reallots array at addr to have size ncells.
  • EXTEND ( addr ncells -- ): extends the array at addr by ncells cells
  • LENGTH ( addr -- len ): pushes the length of the array at addr onto the stack
  • LENGTH? ( addr -- ): prints the length of the array at addr
  • ' xxx ( -- addr ): attempts to find xxx in the dictionary, and pushes an execution token for xxx to the stack if found
  • EXECUTE ( xt -- ): executes an execution token on top of the stack
  • ['] xxx ( -- addr ): currently equivalent to ' for froth