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Diffstat (limited to 'data/stack.scm')
-rw-r--r-- | data/stack.scm | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/data/stack.scm b/data/stack.scm new file mode 100644 index 0000000..c28d648 --- /dev/null +++ b/data/stack.scm @@ -0,0 +1,21 @@ +(define-module (data stack) + #:use-module (control monad) + #:use-module (control monad state)) + +;;; Simple stateful stack module for showing the state monad +;;; in action. These functions assume that they are in a +;;; (state list) monad. But dynamic types! + +(define (pop) + (do st <- (get) + let top = (car st) + (put (cdr st)) + (return-state top))) + +(define (peek) + (do st <- (get) + (return-state (car st)))) + +(define (push v) + (do st <- (get) + (put (cons v st)))) |