steve
/
factor
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

kernel: add examples for if, when, unless and if*

release
Slava Pestov 2010-04-05 17:19:43 -04:00
parent eac2849833
commit d6fb134d5f
1 changed files with 60 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
core/kernel/kernel-docs.factor
View File

@ -575,19 +575,51 @@ HELP: if
{ $values { "?" "a generalized boolean" } { "true" quotation } { "false" quotation } }
{ $description "If " { $snippet "cond" } " is " { $link f } ", calls the " { $snippet "false" } " quotation. Otherwise calls the " { $snippet "true" } " quotation."
$nl
"The " { $snippet "cond" } " value is removed from the stack before either quotation is called." } ;
"The " { $snippet "cond" } " value is removed from the stack before either quotation is called." }
{ $examples
{ $example
"USING: io kernel math ;"
"10 3 < [ \"Math is broken\" print ] [ \"Math is good\" print ] if"
"Math is good"
}
} ;
HELP: when
{ $values { "?" "a generalized boolean" } { "true" quotation } }
{ $description "If " { $snippet "cond" } " is not " { $link f } ", calls the " { $snippet "true" } " quotation."
$nl
"The " { $snippet "cond" } " value is removed from the stack before the quotation is called." } ;
"The " { $snippet "cond" } " value is removed from the stack before the quotation is called." }
{ $examples
{ $example
"USING: kernel math prettyprint ;"
"-5 dup 0 < [ 3 + ] when ."
"-2"
}
} ;
HELP: unless
{ $values { "?" "a generalized boolean" } { "false" quotation } }
{ $description "If " { $snippet "cond" } " is " { $link f } ", calls the " { $snippet "false" } " quotation."
$nl
"The " { $snippet "cond" } " value is removed from the stack before the quotation is called." } ;
"The " { $snippet "cond" } " value is removed from the stack before the quotation is called." }
{ $examples
{ $example
"USING: kernel math prettyprint sequences ;"
"IN: scratchpad"
""
"CONSTANT: american-cities {"
" \"San Francisco\""
" \"Los Angeles\""
" \"New York\""
"}"
""
": add-tax ( price city -- price' )"
" american-cities member? [ 1.1 * ] unless ;"
""
"123 \"Ottawa\" add-tax ."
"135.3"
}
} ;
HELP: if*
{ $values { "?" "a generalized boolean" } { "true" { $quotation "( ..a ? -- ..b )" } } { "false" { $quotation "( ..a -- ..b )" } } }
@ -596,7 +628,31 @@ $nl
"If the condition is true, it is retained on the stack before the " { $snippet "true" } " quotation is called. Otherwise, the condition is removed from the stack and the " { $snippet "false" } " quotation is called."
$nl
"The following two lines are equivalent:"
{ $code "X [ Y ] [ Z ] if*" "X dup [ Y ] [ drop Z ] if" } } ;
{ $code "X [ Y ] [ Z ] if*" "X dup [ Y ] [ drop Z ] if" } }
{ $examples
"Notice how in this example, the same value is tested by the conditional, and then used in the true branch; the false branch does not need to drop the value because of how " { $link if* } " works:"
{ $example
"USING: assocs io kernel math.parser ;"
"IN: scratchpad"
""
": curry-price ( meat -- price )
{
{ \"Beef\" 10 }
{ \"Chicken\" 12 }
{ \"Lamb\" 13 }
} at ;
: order-curry ( meat -- )
curry-price [
\"Your order will be \" write
number>string write
\" dollars.\" write
] [ \"Invalid order.\" print ] if* ;"
""
"\"Deer\" order-curry"
"Invalid order."
}
} ;
HELP: when*
{ $values { "?" "a generalized boolean" } { "true" { $quotation "( cond -- ... )" } } }