diff options
Diffstat (limited to 'guix/monads.scm')
| -rw-r--r-- | guix/monads.scm | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/guix/monads.scm b/guix/monads.scm index 0b0ad239de..317f85d079 100644 --- a/guix/monads.scm +++ b/guix/monads.scm @@ -185,8 +185,9 @@ form is (VAR -> VAL), bind VAR to the non-monadic value VAL in the same way as (define-syntax mbegin (syntax-rules (%current-monad) - "Bind the given monadic expressions in sequence, returning the result of -the last one." + "Bind MEXP and the following monadic expressions in sequence, returning +the result of the last expression. Every expression in the sequence must be a +monadic expression." ((_ %current-monad mexp) mexp) ((_ %current-monad mexp rest ...) @@ -204,23 +205,27 @@ the last one." (define-syntax mwhen (syntax-rules () - "When CONDITION is true, evaluate EXP0..EXP* as in an 'mbegin'. When -CONDITION is false, return *unspecified* in the current monad." - ((_ condition exp0 exp* ...) + "When CONDITION is true, evaluate the sequence of monadic expressions +MEXP0..MEXP* as in an 'mbegin'. When CONDITION is false, return *unspecified* +in the current monad. Every expression in the sequence must be a monadic +expression." + ((_ condition mexp0 mexp* ...) (if condition (mbegin %current-monad - exp0 exp* ...) + mexp0 mexp* ...) (return *unspecified*))))) (define-syntax munless (syntax-rules () - "When CONDITION is false, evaluate EXP0..EXP* as in an 'mbegin'. When -CONDITION is true, return *unspecified* in the current monad." - ((_ condition exp0 exp* ...) + "When CONDITION is false, evaluate the sequence of monadic expressions +MEXP0..MEXP* as in an 'mbegin'. When CONDITION is true, return *unspecified* +in the current monad. Every expression in the sequence must be a monadic +expression." + ((_ condition mexp0 mexp* ...) (if condition (return *unspecified*) (mbegin %current-monad - exp0 exp* ...))))) + mexp0 mexp* ...))))) (define-syntax define-lift (syntax-rules () |