Env (b0.B0_std.Os.Env)

Variables

type var_name = string

The type for environment variable names.

val var : empty_is_none:bool -> var_name -> string option

var ~empty_is_none name is the value of the environment variable name in the current process environment, if defined. If empty_is_none is true, None is returned if the variable value is the empty string.

val var' : 
  empty_is_none:bool ->
  (var_name -> ('a, string) Stdlib.result) ->
  var_name ->
  ('a option, string) Stdlib.result

var' ~empty_is_none parse name is like var but the value is parsed with parse. If the latter errors with Error e, Error (Fmt.str "%s env: %s" name e) is returned.

Process environement

type t

The type for process environments.

val empty : t

empty is an empty environment.

val current : unit -> (t, string) Stdlib.result

current () is the current process environment.

val find : var_name -> t -> string option

find name env lookups name in env.

val override : t -> by:t -> t

override env ~by:over overrides the definitions in env by those in by.

val add : var_name -> string -> t -> t

add name v env is env but with name bound to v

val fold : (var_name -> string -> 'a -> 'a) -> t -> 'a -> 'a

fold f env init folds f on env's bindings starting with env.

val remove : var_name -> t -> t

remove name env is env without a binding for name.

val mem : var_name -> t -> bool

mem name env is true iff name is bound in env.

val pp : t Fmt.t

pp formats environments for inspection.

Process environments as assignments

type assignments = string list

The type for environments as lists of strings of the form "var=value".

val current_assignments : unit -> (assignments, string) Stdlib.result

current_assignments () is the current process environment as assignments.

val of_assignments : ?init:t -> string list -> (t, string) Stdlib.result

of_assignments ~init ss folds over strings in ss, cuts them at the leftmost '=' character and adds the resulting pair to init (defaults to empty). If the same variable is bound more than once, the last one takes over.

val to_assignments : t -> assignments

to_assignments env is env's bindings as assignments.

val pp_assignments : assignments Fmt.t

pp formats assignments for inspection.