diff options
Diffstat (limited to 'txr.1')
| -rw-r--r-- | txr.1 | 54 |
1 files changed, 51 insertions, 3 deletions
@@ -3263,9 +3263,19 @@ These directives allow \*(TX programs to be modularized. They bring in code from a file, in two different ways. .coIP @(do) -The do directive is used to evaluate \*(TL expressions, discarding their +The +.code do +directive is used to evaluate \*(TL expressions, discarding their result values. See the TXR LISP section far below. +.coIP @(mdo) +The +.code mdo +(macro +.codn do ) +directive evaluates \*(TL expressions immediately, during the parsing +of the \*(TX syntax in which it occurs. + .PP .SS* Subexpression Evaluation @@ -6508,10 +6518,12 @@ The syntax of is: .cblk -.mets @(do << lisp-expression ) +.mets @(do << lisp-expression *) .cble -The do directive evaluates a \*(TL expression. (See TXR LISP far +The +.code do +directive evaluates zero or more \*(TL expressions. (See TXR LISP far below.) The value of the expression is ignored, and matching continues continues with the directives which follow the .code do @@ -6532,6 +6544,42 @@ Example: @(do (set [h a] b)) .cble +.dir mdo + +The syntax of +.code @(mdo) +is: + +.cblk +.mets @(mdo << lisp-expression *) +.cble + +Like the +.code do +directive, +.code mdo +(macro-time +.codn do ) +evaluates zero or more \*(TL expressions. Unlike +.codn do , +.code mdo +performs this evaluation immediately upon being parsed. +Then it disappears from the syntax. + +The effect of +.code "@(mdo e0 e1 e2 ...)" +is exactly like +.code "@(do (macro-time e0 e1 e2 ...))" +except that +.code do +doesn't disappear from the syntax. + +Another difference is that +.code do +can be used as a horizontal or vertical directive, whereas +.code mdo +is only vertical. + .SS* Blocks .NP* Overview |