harlowe:lambda
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| * "where" lambdas, used by the [[harlowe:find|(find:)]] macro, are used to search for and filter data. The lambda ''%%_item where _item's 1st is "A"%%'' tells the macro to searches for items whose ''%%1st%%'' is the string "A". | * "where" lambdas, used by the [[harlowe:find|(find:)]] macro, are used to search for and filter data. The lambda ''%%_item where _item's 1st is "A"%%'' tells the macro to searches for items whose ''%%1st%%'' is the string "A". | ||
| * "via" lambdas, used by the [[harlowe:altered|(altered:)]] macro, are used to transform and change data. The lambda ''%%_item via _item + "s"%%'' tells the macro to add the string "s" to the end of each item. | * "via" lambdas, used by the [[harlowe:altered|(altered:)]] macro, are used to transform and change data. The lambda ''%%_item via _item + "s"%%'' tells the macro to add the string "s" to the end of each item. | ||
| - | * "when" lambdas are a variant of "where" used exclusively by [[harlowe:event|(event:)]], and are used to specify a live event when a hook should be shown. The lambda ''%%when $fuel > 8%%'' tells [[harlowe:event|(event:)]] to show the attached hook when ''%%$fuel%%'' is increased (due to an interaction macro like [[harlowe:click-repeat|(click-repeat:)]], a [[harlowe:live|(live:)]] macro, or anything else). This really shouln't be called a "lambda", but you can perhaps think of it in terms of it filtering moments in time that pass or fail the condition. | + | * "when" lambdas are a variant of "where" used exclusively by [[harlowe:event|(event:)]], and are used to specify a live event when a hook should be shown. The lambda ''%%when $fuel > 8%%'' tells [[harlowe:event|(event:)]] to show the attached hook when ''%%$fuel%%'' is increased (due to an interaction macro like [[harlowe:link-repeat|(link-repeat:)]], a [[harlowe:live|(live:)]] macro, or anything else). This really shouln't be called a "lambda", but you can perhaps think of it in terms of it filtering moments in time that pass or fail the condition. |
| * "making" lambdas, used by the [[harlowe:folded|(folded:)]] are used to build or "make" a single data value by adding something from each item to it. The lambda ''%%_item making _total via _total + (max: _item, 0)%%'' tells the macro to add each item to the total, but only if the item is greater than 0. (Incidentally, you can also use "where" inside a "making" lambda - you could rewrite that lambda as ''%%_item making _total via _total + _item where _item > 0%%''.) | * "making" lambdas, used by the [[harlowe:folded|(folded:)]] are used to build or "make" a single data value by adding something from each item to it. The lambda ''%%_item making _total via _total + (max: _item, 0)%%'' tells the macro to add each item to the total, but only if the item is greater than 0. (Incidentally, you can also use "where" inside a "making" lambda - you could rewrite that lambda as ''%%_item making _total via _total + _item where _item > 0%%''.) | ||
| * For certain macros, like [[harlowe:for|(for:)]], you may want to use a "where" lambda that doesn't filter out any of the values - ''%%_item where true%%'', for instance, will include every item. There is a special, more readable shorthand for this type of "where" lambda: writing just ''%%each _item%%'' is equivalent. | * For certain macros, like [[harlowe:for|(for:)]], you may want to use a "where" lambda that doesn't filter out any of the values - ''%%_item where true%%'', for instance, will include every item. There is a special, more readable shorthand for this type of "where" lambda: writing just ''%%each _item%%'' is equivalent. | ||
harlowe/lambda.txt ยท Last modified: 2019/04/16 04:08 by l
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