From d177285a761de33b86fcbde72fd718137bfa6f86 Mon Sep 17 00:00:00 2001 From: Xander Date: Thu, 17 Aug 2023 22:08:21 +0200 Subject: Add valid/unvalid type, replacement of optional --- lib/DATS/valid.dats | 15 +++++++++++++++ lib/SATS/valid.sats | 18 ++++++++++++++++++ 2 files changed, 33 insertions(+) create mode 100644 lib/DATS/valid.dats create mode 100644 lib/SATS/valid.sats (limited to 'lib') diff --git a/lib/DATS/valid.dats b/lib/DATS/valid.dats new file mode 100644 index 0000000..f4ea0aa --- /dev/null +++ b/lib/DATS/valid.dats @@ -0,0 +1,15 @@ +#define ATS_DYNLOADFLAG 0 +staload "lib/SATS/valid.sats" + +assume valid(a:t@ype,b:bool) = (a,bool b) + +implement{a} create_valid(value : a) = (value,true) + +// Create unvalid value by casting null pointer to type. +implement{a} create_unvalid() = let + staload UN = "prelude/SATS/unsafe.sats" +in + ($UN.ptr0_get(the_null_ptr),false) //UNSAFE: +end + +implement{a} unwrap_valid(v) = v.0 diff --git a/lib/SATS/valid.sats b/lib/SATS/valid.sats new file mode 100644 index 0000000..e3841e0 --- /dev/null +++ b/lib/SATS/valid.sats @@ -0,0 +1,18 @@ + +// implement a type that can be unvalid or valid. +// It's a replacement of Optional, but can be allocated on stack, so no heap allocaton needed. +// When unvalid, it should be not possible to get unvalid value, thats why abstract type is used. +// bool b: true means valid, false unvalid +abst@ype valid(a:t@ype,b:bool) = (a,bool b) + +typedef Valid(a:t@ype) = [b : bool] valid(a,b) + +// Wraps valid value. +fn {a:t@ype} create_valid(value : a) : valid(a,true) + +// Creates unvalid type. +fn {a:t@ype} create_unvalid() : valid(a,false) + +// Only function that allows getting value. Only accepts valid values. +fn {a:t@ype} unwrap_valid(valid(a,true)) : a + -- cgit v1.2.3