diff options
| -rw-r--r-- | factor.html.markdown | 40 |
1 files changed, 20 insertions, 20 deletions
diff --git a/factor.html.markdown b/factor.html.markdown index a0726420..79596d83 100644 --- a/factor.html.markdown +++ b/factor.html.markdown @@ -24,33 +24,33 @@ Code in this file can be typed into Factor, but not directly imported because th 5 4 + ! No output ! `.` pops the top result from the stack and prints it. -. ! 9 +. ! 9 ! More examples of arithmetic: -6 7 * . ! 42 -1360 23 - . ! 1337 -12 12 / . ! 1 -13 2 mod . ! 1 +6 7 * . ! 42 +1360 23 - . ! 1337 +12 12 / . ! 1 +13 2 mod . ! 1 -99 neg . ! -99 --99 abs . ! 99 -52 23 max . ! 52 -52 23 min . ! 23 +99 neg . ! -99 +-99 abs . ! 99 +52 23 max . ! 52 +52 23 min . ! 23 ! A number of words are provided to manipulate the stack, collectively known as shuffle words. 3 dup - ! duplicate the top item (1st now equals 2nd): 3 - 3 2 5 swap / ! swap the top with the second element: 5 / 2 -4 0 drop 2 / ! remove the top item (dont print to screen): 4 / 2 +4 0 drop 2 / ! remove the top item (don't print to screen): 4 / 2 1 2 3 nip .s ! remove the second item (similar to drop): 1 3 1 2 clear .s ! wipe out the entire stack -1 2 3 4 over .s ! duplicate the second item to the top: 1 2 3 4 3 +1 2 3 4 over .s ! duplicate the second item to the top: 1 2 3 4 3 1 2 3 4 2 pick .s ! duplicate the third item to the top: 1 2 3 4 2 3 -! Creating Words +! Creating Words ! The `:` word sets Factor into compile mode until it sees the `;` word. : square ( n -- n ) dup * ; ! No output -5 square . ! 25 +5 square . ! 25 ! We can view what a word does too. ! \ suppresses evaluation of a word and pushes its identifier on the stack instead. @@ -88,9 +88,9 @@ Code in this file can be typed into Factor, but not directly imported because th 0 [ "Zero is true" . ] when ! Zero is true f [ "F is true" . ] when ! No output f [ "F is false" . ] unless ! F is false -2 [ "Two is true" . ] [ "Two is false" . ] if ! Two is true +2 [ "Two is true" . ] [ "Two is false" . ] if ! Two is true -! By default the conditionals consume the value under test, but starred variants +! By default the conditionals consume the value under test, but starred variants ! leave it alone if it's true: 5 [ . ] when* ! 5 @@ -100,7 +100,7 @@ f [ . ] when* ! No output, empty stack, f is consumed because it's false ! Loops ! You've guessed it.. these are higher order words too. -5 [ . ] each-integer ! 0 1 2 3 4 +5 [ . ] each-integer ! 0 1 2 3 4 4 3 2 1 0 5 [ + . ] each-integer ! 0 2 4 6 8 5 [ "Hello" . ] times ! Hello Hello Hello Hello Hello @@ -114,7 +114,7 @@ f [ . ] when* ! No output, empty stack, f is consumed because it's false ! Loop reducing or building lists: { 1 2 3 4 5 } [ 2 mod 0 = ] filter ! Keeps only list members for which quotation yields true: { 2 4 } { 2 4 6 8 } 0 [ + ] reduce . ! Like "fold" in functional languages: prints 20 (0+2+4+6+8) -{ 2 4 6 8 } 0 [ + ] accumulate . . ! Like reduce but keeps the intermediate values in a list: prints { 0 2 6 12 } then 20 +{ 2 4 6 8 } 0 [ + ] accumulate . . ! Like reduce but keeps the intermediate values in a list: prints { 0 2 6 12 } then 20 1 5 [ 2 * dup ] replicate . ! Loops the quotation 5 times and collects the results in a list: { 2 4 8 16 32 } 1 [ dup 100 < ] [ 2 * dup ] produce ! Loops the second quotation until the first returns false and collects the results: { 2 4 8 16 32 64 128 } @@ -142,7 +142,7 @@ name get-global . ! "Bob" 2 :> c ! Declares immutable variable c to hold 2 c . ; ! Print it out -! In a word declared this way, the input side of the stack declaration +! In a word declared this way, the input side of the stack declaration ! becomes meaningful and gives the variable names stack values are captured into :: double ( a -- result ) a 2 * ; @@ -150,7 +150,7 @@ name get-global . ! "Bob" :: mword2 ( a! -- x y ) ! Capture top of stack in mutable variable a a ! Push a a 2 * a! ! Multiply a by 2 and store result back in a - a ; ! Push new value of a + a ; ! Push new value of a 5 mword2 ! Stack: 5 10 ! Lists and Sequences @@ -167,7 +167,7 @@ name get-global . ! "Bob" "Concat" "enate" append ! "Concatenate" - strings are sequences too "Concatenate" "Reverse " prepend ! "Reverse Concatenate" { "Concatenate " "seq " "of " "seqs" } concat ! "Concatenate seq of seqs" -{ "Connect" "subseqs" "with" "separators" } " " join ! "Connect subseqs with separators" +{ "Connect" "subseqs" "with" "separators" } " " join ! "Connect subseqs with separators" ! And if you want to get meta, quotations are sequences and can be dismantled.. 0 [ 2 + ] nth ! 2 |